That’s exactly what happened to me, I got confused by Norris and quaffed cure but got confused again the same turn, so I had to drink another one, which is already my last one because I’m with Jiyva who must’ve devoured 100 bottles of all kinds of potions. Luckily my golems took him down the next turn, at the end of which I had 8HP.
It’s sometimes frustrating but I never feel too troubled by that. I rarely cure poison in combat, I usually just drink !heal if my HP gets too low (but I do cure confusion immediately).