anxiety and stress
"I have been on Paxil for 3 months and had gained 6 pounds. Doesn't sound that bad, except I've been going to the gym like crazy to counteract this side effect and still the scale keeps creeping up.  I have almost zero interest in having sex and when I do have sex, I cannot have an orgasm. Any interest in sex I do have is counteracted by the fact that I feel gross having gained extra weight.  If I were single, I might not mind the sex issue as much, but if you are in a relationship, I would consider a different drug."