I started Lexapro at the age of 12 for my severe anxiety. It helped a lot with the anxiety, but it gave me SEVERE suicidal thoughts and urges as a chemical side effect, but those feelings went away after a few months. I eventually stopped taking it at age 14 because it gave me a super bad dry mouth as a side effect, to the point where drinking water and eating food didn't help.
I've been on Remeron, Lexapro, and Zoloft, and Lexapro has worked the best out of all of them. I had no weight changes from it.