Let's talk aboutCYP2C19 Drug Metabolism

What is pharmacogenetics (farm-uh-ko-genetics)?

Pharmacogenetics is a big word for a simple idea — your genetics can influence how you process certain medications. Pharmacogenetics can help your healthcare provider when choosing an appropriate course of treatment.

How does the CYP2C19 gene impact drug metabolism?

The CYP2C19 gene contains instructions for making the CYP2C19 enzyme, which is found in the liver. The CYP2C19 enzyme helps process (or “metabolize”) several commonly used medications. Specific DNA variants in the CYP2C19 gene can affect how well this enzyme works. People with these variants may process certain medications slower or faster than normal.  

What factors besides genetics affect how you process medications?

In addition to genetics, many other factors can influence how people process medications, such as age, weight, liver and kidney function, and drug-drug interactions. It’s the combination of these factors plus genetics that influences how the body processes a medication.

What are some medications processed in part by the CYP2C19 enzyme?

The CYP2C19 enzyme processes several commonly used medications, including:

  • certain proton pump inhibitors, such as omeprazole and pantoprazole (used to treat heartburn, chronic acid reflux, and stomach ulcers),
  • clopidogrel (used to reduce the risk for heart attack and stroke), and
  • certain antidepressants, such as citalopram and escitalopram.

Some other medications processed by the CYP2C19 enzyme include:

  • voriconazole (used to treat fungal infections), 
  • brivaracetam (used to control partial-onset seizures), 
  • clobazam (used to control seizures that occur with Lennox-Gastaut syndrome), and 
  • doxepin (used to treat insomnia).

Did you know?

About 60% of people have at least one variant in the CYP2C19 gene that may influence how they process certain medications. In the U.S., more than 200 million prescriptions are written each year for medications processed by the CYP2C19 enzyme.

Explore more

Curious to learn more? 23andMe Pharmacogenetics reports** can tell you if you have specific DNA variants in the CYP2C19 gene that may influence how you process several medications. The best time to learn about your pharmacogenetics is before starting a medication, so these reports may be helpful now and in the future and can easily be shared with your healthcare provider.

You can get the Pharmacogenetics reports and more with 23andMe+ Premium, an annual membership that includes new premium reports and features throughout the year.

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Please note:

  • The 23andMe Pharmacogenetics reports should not be used to start, stop, or change any course of treatment. Medications should always be taken as directed.
  • These reports do not test for all possible DNA variants that may affect an individual’s ability to process medications.
  • These reports do not account for lifestyle or other health factors that may affect an individual’s ability to process medications.
  • These reports do not determine whether a medication is indicated for an individual.

**23andMe PGS Pharmacogenetics reports: The 23andMe test uses qualitative genotyping to detect 3 variants in the CYP2C19 gene, 2 variants in the DPYD gene and 1 variant in the SLCO1B1 gene in the genomic DNA of adults from saliva for the purpose of reporting and interpreting information about the processing of certain therapeutics to inform discussions with a healthcare professional. It does not describe if a person will or will not respond to a particular therapeutic and does not describe the association between detected variants and any specific therapeutic. Our CYP2C19 Pharmacogenetics report provides certain information about variants associated with metabolism of some therapeutics and provides interpretive drug information regarding the potential effect of citalopram and clopidogrel therapy. Results for SLCO1B1 and DPYD and certain CYP2C19 results should be confirmed by an independent genetic test prescribed by your own healthcare provider before taking any medical action. Warning: Test information should not be used to start, stop, or change any course of treatment and does not test for all possible variants that may affect metabolism or protein function. The PGS test is not a substitute for visits to a healthcare professional. Making changes to your current regimen can lead to harmful side effects or reduced intended benefits of your medication, therefore consult with your healthcare professional before taking any medical action. For important information and limitations regarding Pharmacogenetics reports, visit 23andme.com/test-info/pharmacogenetics/


ClinCalc DrugStats Database version 21.2. “The Top 300 Drugs of 2021.” Retrieved Aug 11, 2021, from https://clincalc.com/DrugStats/Top300Drugs.aspx

Ionova I et al. (2020). “CYP2C19 Allele Frequencies in Over 2.2 Million Direct-to-Consumer Genetics Research Participants and the Potential Implication for Prescriptions in a Large Health System.” Clin Transl Sci. 13(6):1298-1306.

Pratt VM et al. (2018). “Recommendations for Clinical CYP2C19 Genotyping Allele Selection: A Report of the Association for Molecular Pathology.” J Mol Diagn. 20(3):269-276. 

Whirl-Carrillo M et al. (2012). “Pharmacogenomics knowledge for personalized medicine.” Clin Pharmacol Ther. 92(4):414-7.