4 years o.0.

I think it's ok since it's the lowest dose possible that can be sold of Prozac.

I got switched from 10mg Lexapro to 20mg Prozac but I was only on the 10mg Lexapro for a few weeks.

If your prescriber is a psychiatrist then I wouldn't worry much. Try calling a different psychiatrist locally for a second opinion because 4 years is a long time to build tolerance.