What's Going On: If it's big, red, and painful, you're probably experiencing cystic acne, one of the more severe types. "Cystic pimples are caused by genetics and hormonal stimulation of oil glands," says Zeichner. Not only are they large, but they're also notoriously tough to treat. They often recur in the same place, because even if you manage to get rid of one, it can keep filling up with oil again and again, like an immortal pimple.
Scars (permanent): People who get acne cysts and nodules often see scars when the acne clears. You can prevent these scars. Be sure to see a dermatologist for treatment if you get acne early — between 8 and 12 years old. If someone in your family had acne cysts and nodules, you also should see a dermatologist if you get acne. Treating acne before cysts and nodules appear can prevent scars.