Clinical Tool
Washout Period Calculator
For educational purposes only — a decision-support tool, not a substitute for clinical judgment.
Walk through plasma elimination step by step — 50% gone after one half-life, 75% after two, and so on — with actual times at each point. Active metabolites are automatically factored in, clinical switching intervals are shown where they fall on the curve, and for drugs where plasma clearance ≠ clinical effect offset, you'll see why. Because norfluoxetine doesn't care that you stopped the Prozac, and phenelzine's plasma half-life is irrelevant.
Search for a medication to see its elimination timeline.
Walk through each half-life step — 50% gone, 75% gone, and so on — with the actual time at each point. Active metabolites and clinical switching intervals are shown when relevant.
Clinical Disclaimer: Washout periods are estimates based on population pharmacokinetic data from FDA prescribing information. Individual clearance varies with age, hepatic/renal function, CYP450 genotype, drug interactions, and duration of prior treatment. Upper end of reported half-life ranges is used for conservative estimates. Clinical switching intervals (e.g., the 5-week fluoxetine-to-MAOI rule) reflect standard-of-care recommendations and may not require complete pharmacokinetic elimination. Always use clinical judgment.
Need dose conversions? The Equivalent Dose Calculator covers antidepressants, benzodiazepines, stimulants, and antipsychotics with evidence-based conversion ratios.