FDA

U.S. Food and Drug Administration

Government regulatory agency

65 drugs 78 brand products

About FDA

The U.S. Food and Drug Administration (FDA) is the federal agency that reviews and approves prescription drugs. As part of that process it evaluates whether a person's genetics affects how a drug works, and when the evidence is convincing it adds that information to the drug's official label. The FDA maintains a public Table of Pharmacogenomic Biomarkers in Drug Labeling that lists every drug whose approved label references a genetic biomarker.^[1] A companion Table of Pharmacogenetic Associations catalogs gene-drug relationships the agency considers well established.^[2]

What guidance it offers

FDA guidance is regulatory rather than a clinical protocol. A label may note that a genetic subgroup has altered drug levels, carries a higher risk of a side effect, or should receive a different dose, but the wording is often broader than a step-by-step recommendation. Because it is tied to a drug's official labeling, FDA guidance carries significant weight even where the label stops short of a specific dose change. The table below lists every drug for which the FDA has published pharmacogenetic labeling that Gene2Rx reports on.

Visit the FDA source →

Drugs with FDA guidance

Gene2Rx reports FDA pharmacogenetic guidance for 65 drugs, grouped by therapeutic class. Expand any drug to see the FDA recommendation for each metabolizer group, or open its full pharmacogenetics page.

anesthetics

Mivacurium BCHE

Metabolizer group	What it means	FDA recommendation	Evidence
Intermediate Metabolizer BCHE	Results in higher systemic concentrations and higher risk of prolonged neuromuscular blockade.	Avoid use of mivacurium or use with extreme caution and close monitoring; consider alternative agents.	Strong
Poor Metabolizer BCHE	Results in much higher systemic concentrations and a significantly increased risk of prolonged neuromuscular blockade.	Avoid use of mivacurium; select alternative agents not affected by BCHE activity.	Strong
Normal Metabolizer BCHE	Normal BCHE activity and expected metabolism of mivacurium.	Initiate therapy with recommended starting dose and adjust per standard clinical practice.	Strong

Succinylcholine BCHE

Metabolizer group	What it means	FDA recommendation	Evidence
Intermediate Metabolizer BCHE	Results in higher systemic concentrations and higher risk of prolonged neuromuscular blockade.	May administer a test dose to assess sensitivity; if proceeding, administer cautiously via slow infusion with close monitoring.	Strong
Poor Metabolizer BCHE	Results in much higher systemic concentrations and a significantly increased risk of prolonged neuromuscular blockade.	Avoid use of succinylcholine; select alternative agents not affected by BCHE activity.	Strong
Normal Metabolizer BCHE	Normal BCHE activity and expected metabolism of succinylcholine.	Initiate therapy with recommended starting dose and adjust per standard clinical practice.	Strong

antiarrhythmics

Propafenone CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk (arrhythmia).	Use with caution. Monitor for heart rhythm changes due to higher drug levels.	Moderate
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk (arrhythmia). Avoid use in poor metabolizers taking a CYP3A4 inhibitor.	Use with caution. Avoid use if also taking a CYP3A4 inhibitor. Monitor closely for heart rhythm problems.	Strong

anticonvulsants →

Brivaracetam CYP2C19

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C19	Results in higher systemic concentrations and higher adverse reaction risk.	Initiate at standard dose with monitoring for adverse reactions due to higher systemic concentrations.	Moderate
Poor Metabolizer CYP2C19	Results in higher systemic concentrations and higher adverse reaction risk. Consider dosage reductions in poor metabolizers.	Consider dosage reduction due to higher systemic concentrations and increased adverse reaction risk.	Moderate

Clobazam CYP2C19

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Rapid Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C19	Results in higher systemic active metabolite concentrations. Poor metabolism results in higher adverse reaction risk. Dosage adjustment is recommended. Refer to FDA labeling for specific dosing recommendations.	Adjust dose per FDA labeling due to higher active metabolite concentrations and increased adverse reaction risk.	Moderate
Poor Metabolizer CYP2C19	Results in higher systemic active metabolite concentrations. Poor metabolism results in higher adverse reaction risk. Dosage adjustment is recommended. Refer to FDA labeling for specific dosing recommendations.	Reduce dose significantly per FDA labeling due to substantially higher active metabolite concentrations and adverse reaction risk.	Strong

Fosphenytoin CYP2C9

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C9	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C9	May result in higher systemic concentrations and higher adverse reaction risk (central nervous system toxicity). Consider starting at the lower end of the dosage range and monitor serum concentrations. Refer to FDA labeling for specific dosing recommendations. Carriers of CYP2C93 alleles may be at increased risk of severe cutaneous adverse reactions. Consider avoiding fosphenytoin as an alternative to carbamazepine in patients who are CYP2C93 carriers. Genotyping is not a substitute for clinical vigilance and patient management.	Consider starting at the lower end of the dosage range and monitor serum concentrations. Refer to FDA labeling for specific dosing recommendations.	Moderate
Poor Metabolizer CYP2C9	May result in higher systemic concentrations and higher adverse reaction risk (central nervous system toxicity). Consider starting at the lower end of the dosage range and monitor serum concentrations. Refer to FDA labeling for specific dosing recommendations. Carriers of CYP2C93 alleles may be at increased risk of severe cutaneous adverse reactions. Consider avoiding fosphenytoin as an alternative to carbamazepine in patients who are CYP2C93 carriers. Genotyping is not a substitute for clinical vigilance and patient management.	Consider starting at the lower end of the dosage range and monitor serum concentrations. Consider avoiding fosphenytoin in CYP2C9*3 carriers. Refer to FDA labeling for specific dosing recommendations.	Strong

Phenytoin CYP2C9

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C9	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C9	May result in higher systemic concentrations and higher adverse reaction risk (central nervous system toxicity). Refer to FDA labeling for specific dosing recommendations. Carriers of CYP2C93 alleles may be at increased risk of severe cutaneous adverse reactions. Consider avoiding phenytoin as an alternative to carbamazepine in patients who are CYP2C93 carriers. Genotyping is not a substitute for clinical vigilance and patient management.	Consider dose reduction and monitor for CNS toxicity. Avoid phenytoin in CYP2C9*3 carriers if possible. Refer to FDA labeling for specific dosing recommendations.	Moderate
Poor Metabolizer CYP2C9	May result in higher systemic concentrations and higher adverse reaction risk (central nervous system toxicity). Refer to FDA labeling for specific dosing recommendations. Carriers of CYP2C93 alleles may be at increased risk of severe cutaneous adverse reactions. Consider avoiding phenytoin as an alternative to carbamazepine in patients who are CYP2C93 carriers. Genotyping is not a substitute for clinical vigilance and patient management.	Significantly reduce dose or consider an alternative anticonvulsant. Avoid phenytoin in CYP2C9*3 carriers. Monitor closely for CNS toxicity and severe cutaneous reactions.	Strong

antidepressants - SNRI

Venlafaxine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Alters systemic parent drug and metabolite concentrations. Consider dosage reductions.	Consider a lower dose. Your body breaks down venlafaxine much more slowly, leading to higher drug levels.	Moderate

antidepressants - SSRI →

Citalopram CYP2C19

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Rapid Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2C19	Results in higher systemic concentrations and adverse reaction risk (QT prolongation). The maximum recommended dose is 20 mg.	Do not exceed a maximum dose of 20 mg daily due to risk of QT prolongation from higher systemic concentrations.	Strong

Vortioxetine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations. The maximum recommended dose is 10 mg.	Use a reduced maximum dose of 10 mg. Refer to FDA labeling for specific dosing recommendations.	Strong

antidiabetics

Nateglinide CYP2C9

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C9	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C9	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2C9	Results in higher systemic concentrations and may result in higher adverse reaction risk (hypoglycemia). Dosage reduction is recommended. Increase monitoring frequency for adverse reactions. Refer to FDA labeling for specific dosing recommendations.	Reduce nateglinide dose and increase monitoring for hypoglycemia. Refer to FDA labeling for specific dosing recommendations.	Moderate

antiemetics →

Dronabinol CYP2C9

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C9	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C9	May result in higher systemic concentrations and higher adverse reaction risk. Monitor for adverse reactions.	Initiate therapy with standard dose and monitor closely for adverse reactions due to potential for higher systemic concentrations.	Moderate
Poor Metabolizer CYP2C9	Results in higher systemic concentrations and adverse reaction risk (QT prolongation). The maximum recommended dosage should not exceed 36 mg (maximum single dose of 18 mg).	Reduce maximum dosage to no more than 36 mg daily (maximum single dose of 18 mg) and monitor for QT prolongation and other adverse reactions.	Strong

Metoclopramide CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk. The recommended dosage is lower. Refer to FDA labeling for specific dosing recommendations.	Reduce dosage per FDA labeling due to higher systemic concentrations and increased adverse reaction risk.	Strong

antifungals

Voriconazole CYP2C19

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Rapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	Strong
Intermediate Metabolizer CYP2C19	Results in higher systemic concentrations and may result in higher adverse reaction risk.	Monitor drug levels closely and consider dose adjustment due to higher systemic concentrations.	Moderate
Poor Metabolizer CYP2C19	Results in higher systemic concentrations and may result in higher adverse reaction risk.	Monitor drug levels closely and reduce dose. Consider alternative antifungal therapy if adverse reactions occur.	Strong
Likely Intermediate Metabolizer CYP2C19	Results in higher systemic concentrations and may result in higher adverse reaction risk.	Monitor drug levels closely and consider dose adjustment due to higher systemic concentrations.	Moderate
Likely Poor Metabolizer CYP2C19	Results in higher systemic concentrations and may result in higher adverse reaction risk.	Monitor drug levels closely and reduce dose. Consider alternative antifungal therapy if adverse reactions occur.	Strong

antihistimines

Meclizine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	May affect systemic concentrations. Monitor for adverse reactions and clinical effect.	Monitor for adverse reactions and clinical effect. Refer to FDA labeling for specific recommendations.	Moderate
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	May affect systemic concentrations. Monitor for adverse reactions and clinical effect.	Monitor for adverse reactions and clinical effect. Refer to FDA labeling for specific recommendations.	Moderate
Poor Metabolizer CYP2D6	May affect systemic concentrations. Monitor for adverse reactions and clinical effect.	Monitor for adverse reactions and clinical effect. Refer to FDA labeling for specific recommendations.	Moderate

antipsychotics →

Aripiprazole CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk. Dosage adjustment is recommended. Refer to FDA labeling for specific dosing recommendations.	Reduce dose per FDA labeling due to higher systemic concentrations and increased adverse reaction risk.	Strong

Aripiprazole Lauroxil CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations. Dosage adjustment is recommended. Refer to FDA labeling for specific dosing recommendations.	Reduce dose per FDA labeling due to higher systemic concentrations. Refer to prescribing information for specific dose adjustments.	Strong

Brexpiprazole CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations. Dosage adjustment is recommended. Refer to FDA labeling for specific dosing recommendations.	Reduce the dose as recommended by FDA labeling due to higher drug levels.	Moderate

Clozapine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations. Dosage reductions may be necessary.	Consider dosage reductions. Monitor for adverse reactions. Refer to FDA labeling for specific dosing recommendations.	Moderate

Iloperidone CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk (QT prolongation). Reduce dosage by 50%.	Reduce dosage by 50%. Monitor for QT prolongation. Refer to FDA labeling for specific dosing recommendations.	Strong

Perphenazine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk.	Use with caution. Consider a lower dose due to increased risk of side effects.	Moderate

Pimozide CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations. Dosages should not exceed 0.05 mg/kg in children or 4 mg/day in adults who are poor metabolizers and dosages should not be increased earlier than 14 days.	Do not exceed 0.05 mg/kg in children or 4 mg/day in adults. Do not increase dosage earlier than 14 days.	Strong

Thioridazine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk (QT prolongation). Predicted effect based on experience with CYP2D6 inhibitors. Contraindicated in poor metabolizers.	Do not use thioridazine. It is contraindicated for poor metabolizers due to dangerous heart rhythm risks.	Strong

antiretrovirals

Efavirenz CYP2B6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2B6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Ultra Rapid Metabolizer CYP2B6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Rapid Metabolizer CYP2B6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2B6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2B6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2B6	Results in higher systemic concentrations and higher adverse reaction risk (QT prolongation).	Monitor closely for adverse reactions including QT prolongation due to higher systemic concentrations. Consider alternative therapy if adverse reactions occur.	Strong

beta blockers

Carvedilol CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk (dizziness).	Use with caution. Consider a lower dose due to increased risk of dizziness and other side effects.	Moderate

blood thinners

Clopidogrel CYP2C19

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Clopidogrel - label recommended dosage and administration	Strong
Rapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Clopidogrel - label recommended dosage and administration	Strong
Normal Metabolizer CYP2C19	No FDA guidance for this phenotype	Clopidogrel - label recommended dosage and administration	Strong
Intermediate Metabolizer CYP2C19	Results in lower systemic active metabolite concentrations, lower antiplatelet response, and may result in higher cardiovascular risk. Consider use of another platelet P2Y12 inhibitor.	Results in lower systemic active metabolite concentrations, lower antiplatelet response, and may result in higher cardiovascular risk. Consider use of another platelet P2Y12 inhibitor.	Moderate
Poor Metabolizer CYP2C19	Results in lower systemic active metabolite concentrations, lower antiplatelet response, and may result in higher cardiovascular risk. Consider use of another platelet P2Y12 inhibitor.	Results in lower systemic active metabolite concentrations, lower antiplatelet response, and may result in higher cardiovascular risk. Consider use of another platelet P2Y12 inhibitor.	Strong
Likely Intermediate Metabolizer CYP2C19	Results in lower systemic active metabolite concentrations, lower antiplatelet response, and may result in higher cardiovascular risk. Consider use of another platelet P2Y12 inhibitor.	Results in lower systemic active metabolite concentrations, lower antiplatelet response, and may result in higher cardiovascular risk. Consider use of another platelet P2Y12 inhibitor.	Moderate
Likely Poor Metabolizer CYP2C19	Results in lower systemic active metabolite concentrations, lower antiplatelet response, and may result in higher cardiovascular risk. Consider use of another platelet P2Y12 inhibitor.	Results in lower systemic active metabolite concentrations, lower antiplatelet response, and may result in higher cardiovascular risk. Consider use of another platelet P2Y12 inhibitor.	Strong

Warfarin CYP2C9 · CYP4F2 · VKORC1

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C9	No FDA guidance for your genotype	Following clinical dosing guidelines for starting dose	Strong
Intermediate Metabolizer CYP2C9	Alters systemic concentrations and dosage requirements. Select initial dosage, taking into account clinical and genetic factors. Monitor and adjust dosages based on INR.	Follow pharmacogenomic dosing guidelines for optimal starting dose	Strong
Poor Metabolizer CYP2C9	Alters systemic concentrations and dosage requirements. Select initial dosage, taking into account clinical and genetic factors. Monitor and adjust dosages based on INR.	Follow pharmacogenomic dosing guidelines for optimal starting dose	Strong
Normal Metabolizer CYP4F2	No FDA guidance for your genotype	Following clinical dosing guidelines for starting dose	Moderate
Intermediate Metabolizer CYP4F2	May affect dosage requirements. Monitor and adjust doses based on INR.	Follow pharmacogenomic dosing guidelines for optimal starting dose	Moderate
Normal expression VKORC1	No FDA guidance for your genotype	Following clinical dosing guidelines for starting dose	Strong
Decreased expression VKORC1	Alters dosage requirements. Select initial dosage, taking into account clinical and genetic factors. Monitor and adjust dosages based on INR.	Follow pharmacogenomic dosing guidelines for optimal starting dose	Strong
Low expression VKORC1	Alters dosage requirements. Select initial dosage, taking into account clinical and genetic factors. Monitor and adjust dosages based on INR.	Initiate therapy with recommended starting dose.	—

cardiomyopathy

Mavacamten CYP2C19

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Rapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	Strong
Intermediate Metabolizer CYP2C19	Results in higher systemic concentrations and may have higher adverse reaction risk (heart failure). Dosage is based on individual response. The dose titration and monitoring schedule accounts for differences due to CYP2C19 genetic variation, so adjustments based on CYP2C19 genotype are not necessary. Refer to FDA labeling for specific dosing recommendations and monitoring.	Follow FDA labeling dose titration and monitoring schedule. Monitor closely for signs of heart failure due to higher systemic concentrations.	Moderate
Poor Metabolizer CYP2C19	Results in higher systemic concentrations and may have higher adverse reaction risk (heart failure). Dosage is based on individual response. The dose titration and monitoring schedule accounts for differences due to CYP2C19 genetic variation, so adjustments based on CYP2C19 genotype are not necessary. Refer to FDA labeling for specific dosing recommendations and monitoring.	Follow FDA labeling dose titration and monitoring schedule. Monitor closely for signs of heart failure. Use caution due to significantly higher systemic concentrations.	Strong
Likely Intermediate Metabolizer CYP2C19	Results in higher systemic concentrations and may have higher adverse reaction risk (heart failure). Dosage is based on individual response. The dose titration and monitoring schedule accounts for differences due to CYP2C19 genetic variation, so adjustments based on CYP2C19 genotype are not necessary. Refer to FDA labeling for specific dosing recommendations and monitoring.	Follow FDA labeling dose titration and monitoring schedule. Monitor closely for signs of heart failure due to higher systemic concentrations.	Moderate
Likely Poor Metabolizer CYP2C19	Results in higher systemic concentrations and may have higher adverse reaction risk (heart failure). Dosage is based on individual response. The dose titration and monitoring schedule accounts for differences due to CYP2C19 genetic variation, so adjustments based on CYP2C19 genotype are not necessary. Refer to FDA labeling for specific dosing recommendations and monitoring.	Follow FDA labeling dose titration and monitoring schedule. Monitor closely for signs of heart failure. Use caution due to significantly higher systemic concentrations.	Strong

chemotherapies →

Belinostat UGT1A1

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer UGT1A1	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer UGT1A1	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer UGT1A1	May result in higher systemic concentrations and higher adverse reaction risk. Reduce starting dose to 750 mg/m2 in poor metabolizers.	Reduce the starting dose to 750 mg/m2 due to increased risk of side effects.	Strong

Belzutifan CYP2C19

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Rapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2C19	Results in higher systemic concentrations and may result in higher adverse reaction risk (anemia, hypoxia). Monitor patients who are poor metabolizers for adverse reactions.	Initiate at standard dose with enhanced monitoring for anemia and hypoxia due to higher systemic concentrations.	Moderate
Likely Intermediate Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Likely Poor Metabolizer CYP2C19	Results in higher systemic concentrations and may result in higher adverse reaction risk (anemia, hypoxia). Monitor patients who are poor metabolizers for adverse reactions.	Initiate at standard dose with enhanced monitoring for anemia and hypoxia due to higher systemic concentrations.	Moderate

Capecitabine DPYD

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer DPYD	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer DPYD	Results in higher adverse reaction risk (severe, life-threatening, or fatal toxicities). Insufficient data are available to recommend a dosage in intermediate metabolizers. Withhold or discontinue in the presence of early-onset or unusually severe toxicity.	Insufficient data to recommend a specific dosage. Withhold or discontinue in the presence of early-onset or unusually severe toxicity. Refer to FDA labeling for specific recommendations.	Strong
Poor Metabolizer DPYD	Results in higher adverse reaction risk (severe, life-threatening, or fatal toxicities). No dosage has proven safe in poor metabolizers.	Avoid capecitabine. No dosage has proven safe in poor metabolizers. Consider an alternative treatment.	Strong

Erdafitinib CYP2C9

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C9	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C9	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2C9	May result in higher systemic concentrations and higher adverse reaction risk. Monitor for adverse reactions.	Initiate therapy with standard dose and monitor closely for adverse reactions. Consider dose reduction if adverse reactions occur.	Moderate

Fluorouracil DPYD

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer DPYD	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer DPYD	Results in higher adverse reaction risk (severe, life-threatening, or fatal toxicities). Insufficient data are available to recommend a dosage in intermediate metabolizers. Withhold or discontinue in the presence of early-onset or unusually severe toxicity.	Use with extreme caution. No safe dose has been established. Withhold or discontinue if severe side effects occur.	Strong
Poor Metabolizer DPYD	Results in higher adverse reaction risk (severe, life-threatening, or fatal toxicities). No dosage has proven safe in poor metabolizers.	Do not use fluorouracil. No safe dose exists for poor metabolizers. Use an alternative treatment.	Strong

Gefitinib CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk. Monitor for adverse reactions.	Initiate therapy with standard dose and monitor closely for adverse reactions due to higher systemic concentrations.	Moderate

Irinotecan UGT1A1

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer UGT1A1	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer UGT1A1	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer UGT1A1	Results in higher systemic active metabolite concentrations and higher adverse reaction risk (severe neutropenia). Consider reducing the starting dosage by one level and modify the dosage based on individual patient tolerance.	Reduce starting dosage by one level and adjust based on individual patient tolerance. Monitor closely for severe neutropenia.	Strong

Mercaptopurine NUDT15 · TPMT

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Function TPMT	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	Strong
Intermediate Function TPMT	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Intermediate metabolizers may require dosage reductions based on tolerability. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce dose based on tolerability per FDA labeling. Monitor closely for myelosuppression. More substantial reductions may be needed if intermediate for both TPMT and NUDT15.	Strong
Possible Intermediate Metabolizer TPMT	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Intermediate metabolizers may require dosage reductions based on tolerability. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce dose based on tolerability per FDA labeling. Monitor closely for myelosuppression.	Strong
Poor Function TPMT	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Initial dosages should be reduced in poor metabolizers; poor metabolizers generally tolerate 10% or less of the recommended dosage. Refer to FDA labeling for specific dosing recommendations.	Drastically reduce initial dose to 10% or less of recommended dosage per FDA labeling. Consider alternative therapy. Monitor closely for myelosuppression.	Strong
Normal Metabolizer NUDT15	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	Strong
Intermediate Metabolizer NUDT15	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Intermediate metabolizers may require dosage reductions based on tolerability. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce dose based on tolerability per FDA labeling. Monitor closely for myelosuppression. More substantial reductions may be needed if intermediate for both TPMT and NUDT15.	Strong
Possible Intermediate Metabolizer NUDT15	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Intermediate metabolizers may require dosage reductions based on tolerability. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce dose based on tolerability per FDA labeling. Monitor closely for myelosuppression.	Strong
Poor Metabolizer NUDT15	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Initial dosages should be reduced in poor metabolizers; poor metabolizers generally tolerate 10% or less of the recommended dosage. Refer to FDA labeling for specific dosing recommendations.	Drastically reduce initial dose to 10% or less of recommended dosage per FDA labeling. Consider alternative therapy. Monitor closely for myelosuppression.	Strong

Nilotinib UGT1A1

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer UGT1A1	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer UGT1A1	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer UGT1A1	Results in higher adverse reaction risk (hyperbilirubinemia).	Initiate therapy at standard dose with close monitoring for hyperbilirubinemia. Consider dose modification if elevated bilirubin occurs.	Moderate

Pazopanib UGT1A1

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer UGT1A1	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer UGT1A1	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer UGT1A1	Results in higher adverse reaction risk (hyperbilirubinemia).	Use with caution. Monitor liver function due to increased risk of elevated bilirubin levels.	Moderate

Sacituzumab Govitecan Hziy UGT1A1

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer UGT1A1	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer UGT1A1	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer UGT1A1	May result in higher systemic concentrations and adverse reaction risk (neutropenia). Monitor for adverse reactions and tolerance to treatment.	Use with caution. Monitor closely for low white blood cell counts and other side effects.	Moderate

Thioguanine NUDT15 · TPMT

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Function TPMT	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	Strong
Intermediate Function TPMT	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Intermediate metabolizers may require dosage reductions based on tolerability. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce thioguanine dose based on tolerability and monitor for myelosuppression. Refer to FDA labeling for specific dosing recommendations.	Strong
Possible Intermediate Metabolizer TPMT	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Intermediate metabolizers may require dosage reductions based on tolerability. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce thioguanine dose based on tolerability and monitor for myelosuppression. Refer to FDA labeling for specific dosing recommendations.	Strong
Poor Function TPMT	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Initial dosages should be reduced in poor metabolizers; poor metabolizers generally tolerate 10% or less of the recommended dosage. Refer to FDA labeling for specific dosing recommendations.	Consider an alternative agent or reduce dose to 10% or less of the recommended dosage. Monitor closely for myelosuppression.	Strong
Normal Metabolizer NUDT15	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	Strong
Intermediate Metabolizer NUDT15	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Intermediate metabolizers may require dosage reductions based on tolerability. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce thioguanine dose based on tolerability and monitor for myelosuppression. Refer to FDA labeling for specific dosing recommendations.	Strong
Possible Intermediate Metabolizer NUDT15	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Intermediate metabolizers may require dosage reductions based on tolerability. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce thioguanine dose based on tolerability and monitor for myelosuppression. Refer to FDA labeling for specific dosing recommendations.	Strong
Poor Metabolizer NUDT15	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Initial dosages should be reduced in poor metabolizers; poor metabolizers generally tolerate 10% or less of the recommended dosage. Refer to FDA labeling for specific dosing recommendations.	Consider an alternative agent or reduce dose to 10% or less of the recommended dosage. Monitor closely for myelosuppression.	Strong

cholesterol medications →

Simvastatin SLCO1B1

Metabolizer group	What it means	FDA recommendation	Evidence
Increased Function SLCO1B1	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Function SLCO1B1	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Decreased Function SLCO1B1	Results in higher systemic concentrations and higher adverse reaction risk (myopathy). The risk of adverse reaction (myopathy) is higher for patients on 80 mg than for those on lower doses.	Consider lower doses. The risk of muscle injury is increased, especially at higher doses.	Moderate
Possible Decreased Function SLCO1B1	Results in higher systemic concentrations and higher adverse reaction risk (myopathy). The risk of adverse reaction (myopathy) is higher for patients on 80 mg than for those on lower doses.	Consider lower doses. The risk of muscle injury may be increased, especially at higher doses.	Moderate
Poor Function SLCO1B1	Results in higher systemic concentrations and higher adverse reaction risk (myopathy). The risk of adverse reaction (myopathy) is higher for patients on 80 mg than for those on lower doses.	Consider a lower dose or an alternative cholesterol medication. The risk of muscle injury is significantly increased.	Strong

drugs used in addictive disorders

Lofexidine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk. Monitor for orthostatic hypotension and bradycardia.	Initiate therapy with standard dose and monitor closely for orthostatic hypotension and bradycardia. Consider dose reduction if adverse reactions occur.	Moderate

female sexual health

Flibanserin CYP2C19

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Rapid Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2C19	May result in higher systemic concentrations and higher adverse reaction risk. Monitor patients for adverse reactions.	Initiate therapy with standard dose and monitor closely for adverse reactions including hypotension and syncope due to higher systemic concentrations.	Moderate

gaucher's disease treatments

Eliglustat CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	Ultrarapid metabolizers may not achieve adequate concentrations to achieve a therapeutic effect.	Avoid use of eliglustat as adequate therapeutic concentrations may not be achieved. Consider an alternative treatment for Gaucher's disease.	Strong
Normal Metabolizer CYP2D6	Refer to FDA labeling for specific dosing recommendations.	Initiate therapy with recommended starting dose per FDA labeling.	Strong
Intermediate Metabolizer CYP2D6	Alters systemic concentrations, effectiveness, and adverse reaction risk (QT prolongation). Coadministration with strong CYP3A inhibitors is contraindicated in intermediate and poor CYP2D6 metabolizers. Refer to FDA labeling for specific dosing recommendations.	Adjust dose per FDA labeling. Coadministration with strong CYP3A inhibitors is contraindicated. Monitor for QT prolongation.	Strong
Poor Metabolizer CYP2D6	Alters systemic concentrations, effectiveness, and adverse reaction risk (QT prolongation). Coadministration with strong CYP3A inhibitors is contraindicated in intermediate and poor CYP2D6 metabolizers. Refer to FDA labeling for specific dosing recommendations.	Adjust dose per FDA labeling. Coadministration with strong CYP3A inhibitors is contraindicated. Monitor closely for QT prolongation and adverse reactions.	Strong

immunosuppressants →

Abrocitinib CYP2C19

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Abrocitinib - label recommended dosage and administration	Strong
Rapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Abrocitinib - label recommended dosage and administration	Strong
Normal Metabolizer CYP2C19	No FDA guidance for this phenotype	Abrocitinib - label recommended dosage and administration	Strong
Intermediate Metabolizer CYP2C19	No FDA guidance for this phenotype	Abrocitinib - label recommended dosage and administration	Moderate
Poor Metabolizer CYP2C19	Results in higher systemic concentrations and may result in higher adverse reaction risk. Dosage adjustment is recommended. Refer to FDA labeling for specific dosing recommendations.	Results in higher systemic concentrations and may result in higher adverse reaction risk. Dosage adjustment is recommended. Refer to FDA labeling for specific dosing recommendations.	Strong
Likely Intermediate Metabolizer CYP2C19	No FDA guidance for this phenotype	Abrocitinib - label recommended dosage and administration	Moderate
Likely Poor Metabolizer CYP2C19	Results in higher systemic concentrations and may result in higher adverse reaction risk. Dosage adjustment is recommended. Refer to FDA labeling for specific dosing recommendations.	Results in higher systemic concentrations and may result in higher adverse reaction risk. Dosage adjustment is recommended. Refer to FDA labeling for specific dosing recommendations.	Strong

Azathioprine NUDT15 · TPMT

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Function TPMT	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Function TPMT	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Dosage reduction is recommended in intermediate metabolizers for NUDT15 or TPMT. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce dose per FDA labeling to decrease myelosuppression risk. Monitor blood counts closely.	Strong
Possible Intermediate Metabolizer TPMT	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Dosage reduction is recommended in intermediate metabolizers for NUDT15 or TPMT. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce dose per FDA labeling to decrease myelosuppression risk. Monitor blood counts closely.	Strong
Poor Function TPMT	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Consider alternative therapy in poor metabolizers.	Consider alternative immunosuppressant therapy due to significantly increased myelosuppression risk.	Strong
Normal Metabolizer NUDT15	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer NUDT15	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Dosage reduction is recommended in intermediate metabolizers for NUDT15 or TPMT. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce dose per FDA labeling to decrease myelosuppression risk. Monitor blood counts closely.	Strong
Possible Intermediate Metabolizer NUDT15	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Dosage reduction is recommended in intermediate metabolizers for NUDT15 or TPMT. Intermediate metabolizers for both genes may require more substantial dosage reductions. Refer to FDA labeling for specific dosing recommendations.	Reduce dose per FDA labeling to decrease myelosuppression risk. Monitor blood counts closely.	Strong
Poor Metabolizer NUDT15	Alters systemic active metabolite concentration and dosage requirements. Results in higher adverse reaction risk (myelosuppression). Consider alternative therapy in poor metabolizers.	Consider alternative immunosuppressant therapy due to significantly increased myelosuppression risk.	Strong

Siponimod CYP2C9

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C9	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C9	Results in higher systemic concentrations. Adjust dosage based on genotype. Refer to FDA labeling for specific dosing recommendations.	Adjust dosage based on genotype. Refer to FDA labeling for specific dosing recommendations.	Strong
Poor Metabolizer CYP2C9	Results in higher systemic concentrations. Adjust dosage based on genotype. Do not use in patients with CYP2C9 3/3 genotype. Refer to FDA labeling for specific dosing recommendations.	Do not use in patients with CYP2C9 3/3 genotype. For other poor metabolizer genotypes, adjust dosage based on genotype. Refer to FDA labeling for specific dosing recommendations.	Strong

Tacrolimus CYP3A5

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP3A5	Results in lower systemic concentrations and lower probability of achieving target concentrations. Measure drug concentrations and adjust dosage based on trough whole blood tacrolimus concentrations.	Consider a higher starting dose. Measure trough whole blood tacrolimus concentrations and adjust dosage to achieve target levels.	Moderate
Intermediate Metabolizer CYP3A5	Results in higher systemic concentrations. Adjust dosage based on genotype. Refer to FDA labeling for specific dosing recommendations.	Adjust dosage based on genotype and therapeutic drug monitoring. Refer to FDA labeling for specific dosing recommendations.	Moderate
Poor Metabolizer CYP3A5	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—

involuntary movement reducers →

Deutetrabenazine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and adverse reaction risk (QT prolongation). The maximum recommended dosage should not exceed 36 mg (maximum single dose of 18 mg).	Do not exceed a total daily dose of 36 mg (maximum single dose of 18 mg) due to risk of QT prolongation.	Strong

Tetrabenazine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations. The maximum recommended single dose is 25 mg and should not exceed 50 mg/day.	Use a reduced dosage. The maximum recommended single dose is 25 mg and should not exceed 50 mg/day.	Strong

Valbenazine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic active metabolite concentrations and higher adverse reaction risk (QT prolongation). Dosage reductions may be necessary.	Consider a lower dose. Monitor for heart rhythm changes due to increased risk of QT prolongation.	Moderate

pain management →

Carisoprodol CYP2C19

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Rapid Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C19	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2C19	Results in higher systemic concentrations. Use with caution.	Use with caution due to higher systemic concentrations. Monitor closely for adverse reactions and consider reduced dosing.	Strong
Likely Intermediate Metabolizer CYP2C19	Results in higher systemic concentrations and may result in higher adverse reaction risk.	Initiate at standard dose with monitoring for adverse reactions due to potentially higher systemic concentrations.	Moderate
Likely Poor Metabolizer CYP2C19	Results in higher systemic concentrations and may result in higher adverse reaction risk.	Use with caution due to likely higher systemic concentrations. Monitor closely for adverse reactions and consider reduced dosing.	Strong

Celecoxib CYP2C9

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C9	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C9	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2C9	Results in higher systemic concentrations. Reduce starting dose to half of the lowest recommended dose in poor metabolizers. Consider alternative therapy in patients with juvenile rheumatoid arthritis.	Reduce starting dose to half of the lowest recommended dose. Consider alternative therapy for juvenile rheumatoid arthritis patients.	Strong

Codeine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	Results in higher systemic active metabolite concentrations and higher adverse reaction risk (life-threatening respiratory depression and death). Codeine is contraindicated in children under 12 years of age.	Avoid codeine. Use an alternative pain medication. The risk of life-threatening side effects is significantly increased.	Strong
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in lower systemic active metabolite concentrations and may result in reduced efficacy.	Consider an alternative pain medication. Codeine may not provide adequate pain relief.	Moderate

Flurbiprofen CYP2C9

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C9	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C9	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2C9	Results in higher systemic concentrations. Use a reduced dosage.	Use a reduced dosage. Refer to FDA labeling for specific dosing recommendations.	Strong

Meloxicam CYP2C9

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C9	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C9	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose. Monitor for adverse reactions.	—
Poor Metabolizer CYP2C9	Results in higher systemic concentrations. Consider dose reductions in poor metabolizers. Monitor patients for adverse reactions.	Consider reducing the dose due to higher systemic concentrations. Monitor closely for adverse reactions.	Moderate

Oliceridine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk (respiratory depression and sedation). May require less frequent dosing.	Consider less frequent dosing and monitor closely for respiratory depression and sedation.	Moderate

Piroxicam CYP2C9

Metabolizer group	What it means	FDA recommendation	Evidence
Normal Metabolizer CYP2C9	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C9	Results in higher systemic concentrations.	Consider dose adjustment due to higher systemic concentrations. Monitor for adverse reactions.	Moderate
Poor Metabolizer CYP2C9	Results in higher systemic concentrations. Consider reducing dosage in poor metabolizers.	Reduce piroxicam dose to account for higher systemic concentrations. Monitor closely for adverse reactions.	Moderate

Pitolisant CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for this phenotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations. Use lowest recommended starting dosage. Refer to FDA labeling for specific dosing recommendations.	Use the lowest recommended starting dosage. Refer to FDA labeling for specific dosing recommendations.	Strong

Tramadol CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	Results in higher systemic and breast milk active metabolite concentrations, which may result in respiratory depression and death. Contraindicated in children under 12 and in adolescents following tonsillectomy/adenoidectomy. Breastfeeding is not recommended during treatment.	Avoid use. Use an alternative analgesic that is not metabolized by CYP2D6. Contraindicated in children under 12 and adolescents following tonsillectomy/adenoidectomy. Breastfeeding is not recommended.	Strong
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—

proton pump inhibitors →

Pantoprazole CYP2C19

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Rapid Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C19	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2C19	Results in higher systemic concentrations. Consider dosage reduction in children who are poor metabolizers. No dosage adjustment is needed for adult patients who are poor metabolizers.	Consider dosage reduction in children. No dose adjustment is typically needed for adults.	Moderate

psychostimulants

Amphetamine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	May affect systemic concentrations and adverse reaction risk. Consider lower starting dosage or use alternative agent.	Consider a lower starting dose or an alternative medication due to increased risk of side effects.	Moderate

Atomoxetine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk. Adjust titration interval and increase dosage if tolerated. Refer to FDA labeling for specific dosing recommendations.	Extend titration interval and only increase dose if tolerated. Refer to FDA labeling for specific dosing adjustments.	Strong

saliva production stimulators

Cevimeline CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	May result in higher adverse reaction risk. Use with caution.	Use with caution. Monitor for adverse reactions. Refer to FDA labeling for specific recommendations.	Moderate

urologicals

Tolterodine CYP2D6

Metabolizer group	What it means	FDA recommendation	Evidence
Ultrarapid Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Normal Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2D6	No FDA guidance for your genotype	Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2D6	Results in higher systemic concentrations and higher adverse reaction risk (QT prolongation).	Use with caution due to risk of QT prolongation. Consider dose reduction or enhanced cardiac monitoring.	Moderate

Brand products with FDA-guided ingredients

These branded medications contain at least one active ingredient with FDA pharmacogenetic guidance. Each links to its full breakdown.

Abilify

aripiprazole

Adderall

amphetamine, dextroamphetamine

aripiprazole-lauroxil

sacituzumab govitecan-hziy

Tylenol #3

codeine, acetaminophen

simvastatin, ezetimibe

References

U.S. Food and Drug Administration. Table of Pharmacogenomic Biomarkers in Drug Labeling (2024). fda.gov
U.S. Food and Drug Administration. Table of Pharmacogenetic Associations (2024). fda.gov

See your own FDA guidance

This page lists the drugs FDA covers. A Gene2Rx report tells you which metabolizer group you fall into, and what that means for each of these medications.

Get your report All guidance sources

Informational only, not medical advice. The presence of a FDA pharmacogenetic guideline does not mean every patient needs to change their dose. Never start, stop, or change a medication without talking to your prescribing clinician.