Myths vs facts: CYP2D6 and fertility

CYP2D6 is a phase I drug-metabolizing enzyme responsible for breaking down many medications (e.g., antidepressants, beta-blockers, tamoxifen). A direct link to fertility is not scientifically established. Myths often claim that certain CYP2D6 variants influence hormone regulation or detoxification, thereby improving or impairing fertility. The evidence, however, is weak: no robust studies show a causal effect of CYP2D6 polymorphisms on male or female fertility. Some research examines CYP2D6's role in tamoxifen metabolism among breast cancer patients, which can indirectly affect fertility, but this does not translate to a general fertility marker. Effect sizes are small, and clinical relevance for healthy individuals is unclear. A DNA test for CYP2D6 to guide fertility advice is therefore not recommended. Instead, focus on established factors such as age, hormone status, lifestyle, and organic causes. Evidence: unclear. Caveat: do not alter medication or lifestyle based solely on this gene.