You used one when you came off Effexor the first time--"The only way doctors know to soften the blow when withdrawing from short half-life drugs [Effexor is such] is to add 20mg fluoxetine (Prozac). The half-life of Effexor is 5 hours and 99% of it is out of your body in one day. Prozac's half-life is 4 to 6 days and it takes 25 days for 99% of it to be out of your body. Essentially, the Prozac cushions the effect of no Effexor and lets you "ride out" the withdrawal process.–https://natashatracy.com/treatment-issues/withdrawal/antidepressants-effexorpristiq-venlafaxinedesvenlafaxine/. See also https://www.depressionforums.org/forums/topic/107532-coming-off-of-effexor-with-prozac-bridge/