"A retinol purge is really just a temporary adjustment period in which, after starting a new retinol, your skin can get a little bit worse before getting better and it should only last about three weeks," explains Idriss. The irritated, bumpy, or inflamed skin of a purge will get better over time, whereas a reaction will not. "Some people believe these negative effects are all of the toxins coming up to the surface wanting to be released from your body, but this is not true and skincare is not an exorcism," adds Idriss.