Some people may experience a tretinoin purge, in which their skin initially appears worse before improving. Acne that has worsened, dryness, inflammation, redness, etc., are all signs of a tretinoin purge. You can also avoid the possibility of a tretinoin purge. Depending on the individual, Tretinoin purging side effects typically disappear within a few weeks. You might start to see benefits after the tretinoin purge is finished, but it could take up to 12 weeks for acne treatment to start working.