Hey Cootiebug,
Welcome to the depression forum. I am not real familiar with lithium as I have never taken it. I found a site that might give you some insight to the medication.
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000531/
Being it is usually used for bipolar and I am not bipolar, I don't know a lot about this medication. But there are other things it is used for too. We do have some members who do take it and hopefully they will respond to you. I hope that the site helps you too.
Keep posting.
Hugs, Karen