5.Nodules
Nodules are large, inflamed bumps that feel firm to the touch. They develop deep within the skin and are often painful. Nodules should be treated by a dermatologist since they can scar. Over-the-counter treatments may not be powerful enough to clear them up, but prescription drugs can be effective.
6.Cysts
Cysts are large, pus-filled lesions that look similar to boils. Like nodules, cysts can be painful and should be treated by a dermatologist since they also can scar. People who develop nodules and cysts are usually considered to have a more severe form of acne.