How are CYP2D6 and Müdigkeit related?

The relationship between CYP2D6 and fatigue is indirect and primarily mediated by drug metabolism. CYP2D6 is a key enzyme that breaks down many medications, including antidepressants (e.g., SSRIs, tricyclics), beta‑blockers, and antipsychotics. Individuals with reduced CYP2D6 activity („poor metabolizers“) can accumulate higher drug levels, increasing the risk of side effects such as fatigue, drowsiness, or sedation. Conversely, „ultrarapid metabolizers“ may clear drugs too quickly, leading to lack of efficacy – which can also contribute to exhaustion if an underlying condition remains untreated. However, there is no strong evidence that CYP2D6 variants directly cause fatigue in the absence of medication. The link is best described as mechanistic/unclear, as it depends heavily on an individual’s medication profile. A genetic test alone cannot predict current fatigue. Anyone experiencing unexplained tiredness should first investigate common causes like iron deficiency, thyroid dysfunction, or poor sleep quality.