Home › Medication lookup › Genes › CYP2C19
CYP2C19

Drugs affected by CYP2C19

Cytochrome P450 2C19

21 medications 25 brand products

About CYP2C19

CYP2C19 handles several SSRIs (citalopram, escitalopram, sertraline), proton pump inhibitors (omeprazole, esomeprazole), and the blood thinner clopidogrel.[1] 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.[2]

Rapid metabolizers clear affected drugs before they reach therapeutic levels. Poor metabolizers accumulate the drug and feel stronger effects.[3]

What we test for CYP2C19

Gene2Rx uses definitions covering 36 named CYP2C19 star alleles, built from 32 variants in PharmVar. Results depend on the variants available in your upload.

36
Star alleles
32
Defined variants
PharmVar
Source
GRCh38
Genome build
Normal Function 6 Increased Function 1 Decreased Function 6 No Function 14 Uncertain Function 9

Notable CYP2C19 alleles

*1 Normal Function
Reference allele — normal CYP2C19 activity.
*2 No Function
The most common no-function allele worldwide; reduces clopidogrel activation and slows PPI clearance.
~15% in Europeans, ~30% in East Asians
*3 No Function
A no-function allele common in East Asian populations.
~7% in East Asians
*17 Increased Function
An increased-function allele — raises clearance of PPIs, escitalopram, and clopidogrel.
~20% in Europeans
What are star alleles?

Star alleles (like *1, *2, *4) are standardized names for distinct versions of a pharmacogene. *1 is the reference; other numbers identify distinct allele definitions. A higher number does not mean lower function.

You inherit one allele from each parent, so your genotype is a pair (e.g. *1/*4). The pair determines your predicted phenotype — for example, whether you metabolize a drug at a normal, decreased, or no-function rate.

PharmVar is the international registry that defines and curates these allele names. Gene2Rx uses the supported definitions summarized here. Coverage depends on the variants present in your input; this is not a guarantee that every cataloged allele can be identified.

Medications with CYP2C19 information

This list contains 21 medications with CYP2C19 information from the sources shown below. Evidence and report eligibility differ by drug; each page explains its scope and limitations.

cardiomyopathy

female sexual health

Brand products containing a CYP2C19-affected ingredient

These branded medications include at least one active ingredient whose metabolism or action involves CYP2C19. Each links to its full pharmacogenetic breakdown.

References

  1. Clinical Pharmacogenetics Implementation Consortium (CPIC). CPIC Guidelines. cpicpgx.org
  2. PharmGKB / Stanford University. PharmGKB: The Pharmacogenomics Knowledge Base. pharmgkb.org
  3. U.S. Food and Drug Administration. Table of Pharmacogenomic Biomarkers in Drug Labeling (2024). fda.gov

Explore CYP2C19 in your report

A Gene2Rx report interprets supported variants in the context of your data and purchased report. Missing or uncertain calls may prevent an assessment.

Get your report Look up a medication

Informational only, not medical advice. The presence of a CYP2C19 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.

Get Your Report Now
Ready in One Minute