was researching this myself a number of weeks back as there appears to be a good evidence base for lithium for treating people either severely depressed, previously treatment resistant or having exhausted numerous medication options or as an additional augmenting strategy. There's alot that does go with it owing to how it can impact upon your kidneys but i was seriously considered it. I'm unsure as to how quicky people began to see improvements but from reading about it this of course significantly varies from very quick responders to eventual reponders after many months and tampering. Give it a go as I hope that you'll have everything to gain from trying it as it can't be any worse than where you've been.
I have had chronic depression for all my life. About 25 years ago a doctor I saw then tried me on lithium. I took it for over 6 months. It didn't help at all. It had no side effects and was no bother trying and stopping. I did have to get regular blood tests to check levels, etc..
I have never met anyone who had just depression that it ever helped, but it's great for manic depressives. I haven't heard it being mentioned for this in decades. For me an MAOI (Parnate) was the med that truly made a difference in my condition. It is worth trying lithium first as MAO's have their own issues... good luck!
I'm Bipolar II and have been taking Lithium (900mgs) for about a year. I didn't think it was helping me so my Dr took me off of it slowly. I started crying a day or two later and did it every day for several days. I went back on the Lithium and the crying stopped, but I don't think any drug will make you feel as good as you want. I have been on countless meds and nothing has ever really worked. Lithium simply stabilizes my mood so that I am not in bed crying and useless. My mood is blah. I don't cry and I seldom laugh. I feel flat. I don't like it and am going to talk to my Dr today. I don't know if it's the Lithium or the other meds I'm taking: Wellbutrin, Abilify, Lamictal. I do know that without Lithium I am an emotional mess. This is just my experience. I wish you luck with your finding the right meds.