"i&#039;ve been taking prozac for about 4 years. i took 10mg, then 20mg as of last year. it worked very well for a very long time, and i felt great for years, but i&#039;m finally starting to feel a tolerance to it&#039;s effect, and it might be time to switch medications, but it&#039;s certainly been a good run. it helped me feel better, and lifted my depression."