Nobody really knows long-term effects there are (if any)
with antidepressants. However,
Prozac is the oldest SSRI out there, and people have been on it 20+ years, with no serious long-term effects reported yet. In generally, the SSRI antidepressants appear to be very safe. Though their long-term effects have not been adequately studied. Being on Prozac for 2-3 years should have no lasting detrimental effects. I was on Prozac for 3 years, and I'm now on Lexapro for 2 years.