How long does valium stay in your urine?

Valium (diazepam) or it's active metabolite can be detected in your system for up to 23 days. It's active metabolite has an elimination half life of approximately 100hours. It takes 5.5 x elimination half life for a medicine/metabolite to be cleared from ones system so it would take approximately 550 hours or 22.9 days (5.5 x 100 hours) for it's metabolite to be cleared.

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Elimination of diazepam: The initial distribution phase is followed by a prolonged terminal elimination phase (half-life up to 48 hours). The terminal elimination half-life of the active metabolite N-desmethyldiazepam is up to 100 hours. Diazepam and its metabolites are excreted mainly in the urine, predominantly as their glucuronide conjugates. The clearance of diazepam is 20 to 30 mL/min in young adults. Diazepam accumulates upon multiple dosing and there is some evidence that the terminal elimination half-life is slightly prolonged.