re probably suffering some kind of
withdrawal or side effect. Quitting Effexor
cold turkey is pretty nutso, but maybe the psychiatrist felt switching to Pristiq wouldn't present the withdrawal problem because the two drugs are so similar, Pristiq being basically Effexor with some of the molecule cut away. If this is your only side effect so far, it could also be your brain just shedding some stuff, which is what nightmares are.