I was taking effexor (venlafaxine) for approximately 1 year. with the help of my doctor i managed to wean off. how long will i experience withdrawl symptoms?

About 3-4 weeks: Although Effexor (venlafaxine) has a relatively short half-life and is out of your system already, your body has gotten used to its presence and certain receptor sites changed as a result. I find that it takes about 3-4 weeks for the discontinuation symptoms to subside, and i often recommend that my patients take an occasional small dose of the medication if the discontinuation symptoms become unbearable.