Antidepressants: Can They Lose Effectiveness Over Time?

Mayo Clinic psychiatrist Daniel Hall-Flavin, M.D., answers:

I’ve been taking Prozac for depression for several years. In the last few months, I’ve noticed the medication doesn’t seem to be having the same effect, and I feel more depressed. Can you explain this?……a patient questions:
Answer
You describe a phenomenon that affects approximately 20 percent of people who take [...]