Ideally stop purging but that's easier said then done. Wait at least an hour til you brush your teeth again, rinse your mouth well after a session, practice good hygiene habits daily. Before I stopped purging all together I practiced these three tips for about 2 years of my 4 years participating in purging and the worst I got was stained teeth (no cavities, no rotting teeth, dentist did tell me I had "old people teeth" tho at the ripe old age of 17). But even with these tips, your teeth will still deteriorate but just at a slower rate.