In my experience, Buspar is not a medicine that you take and suddenly feel "better". It has to get into your system. I could never tell much that it was having an effect on me until I decided to stop taking it. After I'd been off of it for a short while, my anxiety started to feel more intense, so I started taking it again and have ever since. It didn't cause me any weight gain, which is a good thing for me, since I'm very overweight as it is! But I'll say it to ANYONE: If I had to choose between taking my meds and feeling fairly normal , but it meant gaining lots of weight, I'd still take them! It's not because I like being big, but if no meds meant I'd feel how I was, with all the anxiety and depression, along with being slim, what happiness could I get from being so miserable all the time, just to be slim? I'm not looking for "happiness" from meds, just a tolerable life! :)
Please stick to the Buspar, because as it has been brought out already, it is not addictive and it does help some. I've never heard of it causing weight gain either, but I can't say for a fact that it won't.
Have they not tried replacing your Lexapro with another AD??!!! When zoloft pooped out on me (I was already on buspar), they tapered the zoloft and and slowly added the paxil in its place. I'm curious to know! I hope they help you like you deserve!