If I miss doses, for whatever reason, it take days for me to recover. However, my Rheumie has told me that some people fluctuate their doses all the time, depending on how they're feeling. I tried to wean off Plaquenil at one point, with doctor's approval. I thought I was doing great. Than I had a flare that set me back further than I'd ever been. Unfortunately, you won't know how your body will behave until you've done it. I guess all you can do is weight the risks for your own body.
I hate the meds, wish I could flush them all.
I take plaquenil and decided that I wanted to try cutting back. (I had discussed it with my doctor on one of my previous visits.) I cut back from 400 mg. to 200 mg., and have not had any ill effects. I may go down to 50 mg; it depends on what my rheumie says during my next visit.
I know I missed one dose and, to my amazement, every symptom that I had before the plaquinel came on w/ a vengence.
If you just stop taking plaquenil, expect your symptoms to surface. Usually full force.