I've been on Lexapro for about 10 months. The only side effect I noticed was that the first couple weeks on it I had more headaches that usual. That went away. I noticed improvement in my depression right away, though it wasn't enough. I started out at 10mg and pretty quickly went up to 20mg. Now I've been on 30mg for about a week. I've noticed that I've been able to back off on my Ambien because the increse in dosage has helped me fall asleep at night and stay asleep. Good luck, let us know how it goes for you.