Avoid all drugs, they'll only make it worse. Ideally that should include cigarettes and coffee too. Try and be completely clean for a few months, I've heard it really help and in some cases cure peoples' HPPD. I can't guarantee it'll work for you, but it doesn't cost you anything to try, and there haven't been a whole lot of success stories for curing HPPD so it's a case of trying whatever's available.
You could probably resume with whatever drugs you take once symptoms have lessened or faded completely, but I'd definitely avoid psychedelics, dissociatives, and cannabis for a good while even after that, just to be on the safe side.