How long before 3 doses of prozac (fluoxetine) outvof system?

2 wks: I am not sure if you mean the 3 doses of Prozac were taking at the same time or different days. It usually takes 2 wks to wash Prozac out of the system b/c of the long half life of the active metabolite of prozac, norfluoxetine.

4 to 5 weeks: Prozac (fluoxetine) has a half life of 7 days and it takes at least 4 half lifes or more to clear your body.