Pharmacogenomics

Pharmacogenomics is the study of how your genes change the way you respond to drugs, both how well they work and how toxic they are. The genes that matter most code for drug-metabolizing enzymes, transporters, and drug targets. The classic example is the blood thinner warfarin: variants in CYP2C9 and VKORC1 mean some people need much lower doses to anticoagulate safely, and genotype-guided dosing reduces bleeding. For statins, a variant in SLCO1B1 (rs4149056, Val174Ala) slows the liver's uptake of simvastatin and atorvastatin, which raises drug levels and multiplies the risk of muscle pain (myopathy) in people with two copies. Pharmacogenomics is especially useful for older adults on many drugs at once, because drug-drug-gene interactions stack up with age-related changes in kidney and liver function. Testing a whole panel ahead of time is spreading, and CPIC guidelines now give evidence-based dose advice for over 40 drug-gene pairs.

Last reviewed: June 22, 2026

This definition is educational and is not medical advice, a diagnosis, or treatment. Talk to a doctor about any health decisions. Read our full medical disclaimer