How long does it take for the effexor withdrawal brain zaps to go away after total withdrawal from taking the drug? Over a few weeks, I've successfully tapered down from 150mg to 75mg to 37.5mg but anything lower than 37.5mg gives me serious brain zaps. The brain zaps are so bad that I decided to completely stop taking the med and endure the zaps. Wonder how long it will take to go away.