I am coming off zoloft, (sertraline) it worked for me last time, saved me. this time a year or two later it isn't working. did i build up a tolerance?

Probably.: Some people have reported this phenomena that when they get off an antidepressant and they have to take it again for recurrence of depression, they notice that it takes a bigger dose to relieve their depression . I have read this in some literature and i have seen this with some of my patients. In fact, when the same antidepressant is restarted, you have to start with a higher dose.