After years of taking it off and on for allergies and for sleep, I am convinced that after a few days it starts to have the opposite effect...I get wired from it...and so it's easy to think I need to up the dose...voila, vicious circle. Apparently it causes a "paradoxical reaction" in some people.
I don't take it at all anymore. I do have an rx for hydroxyzine, but I find the prescription strength too strong and often dump out half the capsule first. It works pretty well, though...