I started taking citalopram a week ago. I had taken Lexapro for ...

I started taking citalopram a week ago. I had taken Lexapro for 3 months prior to that, but my insurance company was switched and they wouldn't cover Lexapro until I tried something else first. I didn't really notice any side effects that were different from Lexapro. When I first started taking Lexapro I was really really tired and had a headache and little appetite. However this weekend I got really sick and was vomiting and still feel naseaus the past two days. It had been several days since I started taking it so I don't know if it was from that or something else. I have also had problems falling asleep at night so I have switched to taking it in the morning. I also am worried about weight gain since I think I need to lose weight. While on lexapro I did not gain any weight and my sex drive actually increased, but since I had none before that wasn't much. I hope with citalopram I don't have any more side effects.