You got your GeneSight report and you want to know what it means. This guide explains how the color-coded tier system works, what the metabolizer categories (poor, intermediate, normal, rapid, ultrarapid) tell you, and what the report does not cover. If you want pharmacogenetic information on medications outside GeneSight's psychiatric focus, you can often get that from your existing 23andMe or AncestryDNA data without a second test.
Do not start, stop, or change any medication based solely on your GeneSight report or any other pharmacogenetic report. Always discuss the results with your prescribing clinician before making changes.
GeneSight reports medications into three categories. Green means 'use as directed,' indicating no significant gene-drug interaction based on your genotype. The medication should behave roughly as expected at standard doses for you. Yellow means 'moderate gene-drug interaction,' signaling that your genotype may affect how the medication works or how you tolerate it, and your prescriber may want to adjust dose, monitor more carefully, or consider alternatives. Red means 'significant gene-drug interaction,' which is GeneSight's strongest warning that a different medication may work better for you.
The color tier is a summary. It compresses several pieces of information into one category: which genes are involved, what phenotype you have (e.g., CYP2C19 poor metabolizer), what the specific clinical guideline says about dose or substitution, and how strong the evidence is. A yellow classification based on a Strong CPIC recommendation is different from a yellow classification based on softer evidence, but both show up as yellow. To understand the specific recommendation and how confident to be in it, read the genotype and phenotype details on the page for that medication.
Your GeneSight report will identify you as poor, intermediate, normal, rapid, or ultrarapid metabolizer for each relevant gene (CYP2D6, CYP2C19, CYP2C9, CYP3A4, CYP1A2, CYP2B6). This is the same information any reputable pharmacogenetic test would produce from the same genotype. If you wanted to get a second perspective on the same results, a service like Gene2Rx can interpret your 23andMe or AncestryDNA data against CPIC guidelines and show you how the same phenotypes map to medications outside GeneSight's psychiatric panel.
GeneSight's panel is optimized for psychiatry. It does not report SLCO1B1 (which affects statin response and muscle pain), DPYD (critical for fluoropyrimidine chemotherapy safety), TPMT and NUDT15 (required before azathioprine or mercaptopurine), UGT1A1 (relevant for irinotecan and nilotinib dosing), or VKORC1 (major determinant of warfarin dose). If you take or are considering any medication affected by these genes, GeneSight will not cover it, and a broader pharmacogenetic analysis is worth considering.
GeneSight's report language centers on metabolizer phenotypes. Here is what each means in practice, with CPIC-based interpretation that is consistent across any pharmacogenetic test.
If GeneSight identifies you as a CYP2D6 poor metabolizer, drugs like paroxetine, venlafaxine, fluoxetine, tramadol, and codeine will behave differently for you than for a normal metabolizer. For most CYP2D6 drugs, you will have higher blood levels and more side effects at standard doses. For prodrugs like codeine, you may get less effect because you cannot activate the drug. Ultrarapid CYP2D6 metabolizers are the opposite: standard doses may feel weak, but codeine toxicity risk is elevated.
CYP2C19 poor metabolizers on SSRIs like sertraline, escitalopram, or citalopram often have higher plasma levels and more side effects at standard doses. CPIC recommends dose reduction. CYP2C19 ultrarapid metabolizers may need higher doses or alternative medications. Outside psychiatry, CYP2C19 is critical for clopidogrel (poor metabolizers have reduced clot protection) and omeprazole (rapid metabolizers may not achieve adequate acid suppression).
CYP2C9 matters most for warfarin dosing, where poor metabolizers need substantially lower doses to achieve the same INR. It also affects some NSAIDs and phenytoin. GeneSight reports CYP2C9, but without VKORC1 (which GeneSight does not test) the warfarin dosing picture is incomplete.
Your metabolizer phenotype for each gene is a durable, lifelong attribute. Once you know it, the information applies to every current and future medication that gene affects. That is why many patients find it valuable to get a broader pharmacogenetic profile than a psychiatric-focused panel provides: the same CYP2D6 or CYP2C19 status that guides psychiatric prescribing also informs decisions about pain medications, cardiovascular drugs, and PPIs.
You already did the hard part: you have pharmacogenetic genotype data. Getting a broader interpretation of the same underlying data is the easiest incremental investment in understanding your drug response. If you have existing 23andMe or AncestryDNA data (many patients do), a direct-to-consumer pharmacogenetic service can interpret that data against CPIC guidelines across every major drug class.
Learn how genetics may affect your response to these related medications:
Yellow means your genotype suggests a moderate gene-drug interaction with that medication. Read the genotype and phenotype details on the medication page to see which gene is involved (usually CYP2D6 or CYP2C19) and what CPIC recommends for that phenotype. Yellow is not a directive to stop the medication. It is a flag that your metabolizer status may affect how well the medication works or how you tolerate it, and your prescriber should be aware when making dose decisions.
CYP2D6 affects many non-psychiatric medications too. Poor metabolizers may be at risk of higher-than-expected blood levels on tramadol, metoprolol, amphetamine-based ADHD medications, and tamoxifen. They may also get less effect from codeine because poor metabolizers cannot activate codeine to its active form. GeneSight will not have commented on these medications. A broader pharmacogenetic report can.
Your genotype is your genotype. A second test on the same DNA will produce the same metabolizer phenotype. What can be worth getting is a broader interpretation of the same underlying data. If you have 23andMe or AncestryDNA data, a service that interprets it against CPIC guidelines will cover medications GeneSight did not without requiring a new sample.
Pharmacogenetic testing is one input to prescribing, not the only one. Medication response is affected by many factors including genetics, drug interactions, adherence, underlying conditions, and simple inter-individual variability. A green GeneSight tier means pharmacogenetics is unlikely to be the reason a medication failed you, so the clinical investigation should focus on other factors.
For most medications it means your metabolizer status falls outside the normal range enough that standard dosing may need adjustment or more careful monitoring. It does not mean the medication is unsafe. Your clinician will use the information to decide whether to start at a lower dose, titrate more slowly, monitor for specific side effects, or consider an alternative based on the overall picture.
Find out how your DNA may influence your response to Sertraline and other medications with a Gene2Rx pharmacogenetics report.
Get Your Report Try Our Free Calculator