Pristiq is essentially the same medication as Effexor. It has a half life of 11 hours. I can only surmise that withdrawal from Pristiq might be just as difficult as withdrawal from Effexor. It has been nearly 1 year since completely stopped taking venlafaxine and I still have physical and emotional issues from withdrawal. ie anxiety, fatigue, problems maintaining blood sugar levels (too low), intermittent depression, problems sleeping. Some of these symptoms are probably related to my grief due to the loss of my daughter. It has been a night mare.