Millions of people deal with acne, but those who suffer from cystic acne know how difficult it is to treat compared to ordinary pimples. As its name suggests, cystic acne is a severe form of acne that results in large, pus-filled cysts forming underneath the skin’s surface, which usually makes them more painful than normal bumps and, depending on the severity, can cause scarring, says Dr. Emma Weiss, a board-certified dermatologist and assistant professor of dermatology at the University of Colorado Anschutz Medical Campus.