Yes antidepressants work. I don't know if I would still be here right now without them. I've been on many different ones and how well they work and the side effects of each can vary greatly. But as z7z pointed out the medications you are asking about aren't classified as antidepressants (although lithium can be used as one).
JoseMaria wrote:they're telling me that I should medicate for life because that would prevent relapses, but on what is this based?
Bipolar disorder is a mental illness that goes in cycles. The length of the cycles is different for each person, but if this is your diagnosis you can pretty much count on the illness repeating itself even when you are feeling okay. This is why your Dr. wants you to stay on your medications.
So I went back through some of your older posts and couldn't tell if you are diagnosed with BP 1 or BP 2, but regardless it seems like lithium is not working for you. I would go back to your Dr. and let them know that and also tell them that you had been on lamotrigine in the past and that it worked for you. Different patients with the same illness respond differently to the same medication so unfortunately there is some trial and error finding what works best for each person.
Take care,
-S