depression
"Lexapro is amazing for blocking out over thinking anger and rage. It's a miracle pill. BUT, I was 120 pounds, model skinny. I'm 5'8 I had an amazing metabolism my body was rock solid. After 2 years of Lexapro I am now 170 pounds. Even when I try to work out and eat healthy the scale doesn't move. Sure will lose about 4 pounds and that's it. 
Don't take this medicine if you don't want to gain weight. I have never been fat in my entire life, and now I am more depressed then ever."