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A 51-year-old male asked:

How long does it take for prozac (fluoxetine) to leave your system completely after discontinued?

2 doctor answers5 doctors weighed in
Dr. Imad Khreim
Psychiatry 40 years experience
Apprx. 20 days: Prozac (fluoxetine) is a long acting medicine , between the original compound and the active metabolite the half life is around 96 hrs , so it takes approximately five times that for the level to drop to negligible.
Dr. Tariq Halim
Psychiatry 15 years experience
Long Half-life: Usually around 21-35 days if you take into consideration prozac's metabolite (norfluoxetine).

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A 37-year-old member asked:

How long will it take for Prozac (fluoxetine) to leave my system?

1 doctor answer1 doctor weighed in
Dr. Donald Hazlett
Psychiatry 55 years experience
Quite a while: Prozac (fluoxetine) taken over a period of three or more months, then stopped, can show the presence of fluoxetine for five or more weeks. Prozac has both a right and left isomer (like looking at yourself in the mirror and raising your hand and watching your raised r hand appear to be your l hand). Breakdown of fluoxetine yields nor-fluoxetine which lasts 2 x as long in the body as fluoxetine.
A 45-year-old member asked:

How long does it take for Prozac (fluoxetine) to become effective?

1 doctor answer8 doctors weighed in
Dr. Steven Reidbord
Psychiatry 37 years experience
3 weeks or more: Most ssris start to show effectiveness against depression about 2 weeks after starting them. Prozac (fluoxetine) is about 1 week slower due to its long half-life (it takes longer to reach a steady blood level). So a good estimate is about 3 weeks. But everybody's different; some people feel better faster, others need to wait longer. Also, improvement is gradual, it doesn't become "effective" all at once.
Last updated May 7, 2016


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