Is Valium affected by genetics?

Yes — the active ingredient is metabolized by a gene known to vary between individuals.

Relevant genes: CYP2C19

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Valium is affected by pharmacogenetics through the CYP2C19 gene. Your genotype for this gene can change how your body processes Valium, which can affect both how well it works and how well you tolerate it. The strongest evidence level on this page is Moderate, based on CPIC or FDA guidelines.

What's in Valium

diazepam affected by CYP2C19

Affected by CYP2C19 · Gene2Rx · Moderate evidence

Read the full diazepam genetics guide →

Diazepam phenotype recommendations

Published guidance from Gene2Rx on how diazepam should be dosed or substituted based on your CYP2C19 phenotype.

Phenotype	What it means	Recommendation	Evidence
Ultrarapid Metabolizer CYP2C19	Your body clears diazepam faster, so you may need a higher dose to feel its effect.	Gene2Rx Consider increasing dose by 25–50% and monitor clinical response and sedation levels.	Moderate
Rapid Metabolizer CYP2C19	Your body clears diazepam faster, so you may need a higher dose to feel its effect.	Gene2Rx Consider increasing dose by 25–50% and monitor clinical response and sedation levels.	Moderate
Normal Metabolizer CYP2C19	No expected impact of your genotype on response to this drug.	Gene2Rx Initiate therapy with recommended starting dose.	—
Intermediate Metabolizer CYP2C19	No expected impact of your genotype on response to this drug.	Gene2Rx Initiate therapy with recommended starting dose.	—
Poor Metabolizer CYP2C19	Your body clears diazepam more slowly, so you may need a lower dose to avoid too much drowsiness or breathing problems.	Gene2Rx Consider reducing the dose by 25–50% and closely monitor sedation and respiratory status.	Moderate
Indeterminate CYP2C19	The impact of your genotype on response to this drug is unknown.	Gene2Rx Initiate therapy with recommended starting dose.	—
Not available CYP2C19	The impact of your genotype on response to this drug is unknown.	Gene2Rx Initiate therapy with recommended starting dose.	—

Source: Gene2Rx

The gene behind the guidance

CYP2C19 Cytochrome P450 2C19

CYP2C19 handles several SSRIs (citalopram, escitalopram, sertraline), proton pump inhibitors (omeprazole, esomeprazole), and the blood thinner clopidogrel. About 2 to 5 percent of people of European descent and 15 to 20 percent of people of East Asian descent are poor metabolizers. Another 30 percent carry a rapid-metabolizer variant.

Rapid metabolizers clear affected drugs before they reach therapeutic levels. Poor metabolizers accumulate the drug and feel stronger effects.

See all drugs affected by CYP2C19 →

Related medications

Find out how your genetics affect Valium

This page describes the general pharmacogenetics. A Gene2Rx report analyzes your own DNA to tell you which metabolizer group you fall into, across every medication.

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Informational only — not medical advice. Pharmacogenetic guidance describes population-level patterns; your individual response depends on many factors. Never start, stop, or change a medication without talking to your prescribing clinician.