"i&#039;m 22, and my doctor changed me from effexor to pristiq for my ocd and ocpd. most noticeable side effect is definitely the appetite loss, but i don&#039;t seem to be losing much weight thankfully. if i&#039;m busy and don&#039;t think about it, i go all day without food- it&#039;s nuts. also i am having a lot of headaches, but i cannot be sure its the medicine. i sweat a lot on this, and if i take it too late in the day i cannot sleep. my ocd seems to be in check- much better than effexor. i&#039;ve been taking 50 mg for 5 months now."