What is the washout period between an MAOI and fluoxetine (Prozac)?

• A. 2 weeks
• B. 5 weeks
• C. 8 weeks
• D. 12 weeks

Answer: (B)

Combining MAO inhibitors with fluoxetine creates a high risk of serotonin syndrome because both increase serotonin activity in the brain, and fluoxetine stays in the body for a long time due to its long half-life and active metabolite. To avoid this dangerous overlap, a substantial washout period is needed so that the MAOI’s effect on blocking serotonin breakdown and fluoxetine’s lingering serotonin elevation can dissipate before they are used together again. Five weeks is the typical period recommended, reflecting fluoxetine’s extended pharmacokinetics. This longer interval is why five weeks is the best answer here, whereas shorter washouts wouldn’t reliably prevent interaction with a subsequently started MAOI or fluoxetine.