Effexor did it to me- someone told me it was brain shivers. Hit me like a zap and some part of my body, i.e. arm, hand, leg, etc. would twitch/jerk real hard. Sometimes it would be my head that jerked or twitched to the side- very disturbing (and embarassing) when talking to people or in public.
I'm weaning off Effexor now and the spasms have slowed down a lot. Hopefully they'll disappear altogether once it's completely out of my system...
