Evidence check: CYP2D6 in the context of Sport

CYP2D6 is a key phase I drug-metabolizing enzyme responsible for breaking down many medications (e.g., opioids, beta-blockers, antidepressants). In a sports context, it is discussed mainly regarding metabolism of painkillers and performance-related substances. Genetic variants (poor, intermediate, extensive, ultrarapid metabolizers) can affect drug efficacy and toxicity. However, there is no robust evidence that CYP2D6 variants directly predict athletic performance or injury risk. Most studies are pharmacokinetic and not tailored to athlete populations. DTC tests promoting CYP2D6 for sport often overstate clinical relevance. Single-gene interpretation without medical supervision is not advisable. Evidence: mechanistic/unclear. Caveat: No prediction of sport performance; drug interactions must be evaluated individually.