How are CYP2C19 and Müdigkeit related?

CYP2C19 is a liver enzyme that metabolizes many common drugs, including certain antidepressants (e.g., escitalopram) and proton pump inhibitors (e.g., omeprazole). Genetic variants (*2, *3, *17) affect enzyme activity. Poor metabolizers may accumulate higher drug levels, potentially causing fatigue as a side effect. Ultrarapid metabolizers may clear drugs too quickly, leading to reduced efficacy – for example, inadequate depression treatment can itself cause tiredness. However, CYP2C19 is not a 'fatigue gene'; the link is indirect and drug-dependent. Consumer DNA tests often overstate this connection. Without a doctor's guidance, do not change medications based on genetic results. The evidence is mechanistic, not from large randomized trials. Fatigue has many causes; a single SNP is rarely decisive.