Probably a question for your psychiatrist. When you went up to 40 did any side effects increase or did you get any new ones? The maximum recommended dose is 30mg, and most top out at 20. I know when I went up to 30 there were weird side effects. So a question -- did your psychiatrist taper you off the Lexapro as slowly as you needed or did you just quit and switch? The emotional wreck part might be a withdrawal reaction if you just switched, as no two drugs work exactly the same. If you're gaining weight, the Zoloft is being metabolized, but you don't say how long you've been on it. You're also still on a low dose of Zoloft, so the positive effects of it might not be felt yet, but if you're already gaining weight -- you don't say how much -- some of them do that to you. I see two possibilities, given you seem to want to go back on the Lexapro -- you can try it again after slowly tapering off the Zoloft -- maybe the break in time off it will allow it to work again. Not likely to happen, but possible, depending on how long has passed. Or you could try Celexa, which is almost the same drug as Lexapro but enough different that it might help you the way the Lexapro did. No way to know, though, other than trial and error. Good luck.