This article was medically reviewed by Hilary Baldwin, MD. Baldwin, medical director of the Acne Treatment Research Center, is a board-certified dermatologist with nearly 25 years of experience. Her area of expertise and interest are acne, rosacea and keloid scars. Baldwin received her BA and MA in biology from Boston University. She became a research assistant at Harvard University before attending Boston University School of Medicine. She then completed a medical internship at Yale New Haven Hospital before becoming a resident and chief resident in dermatology at New York University Medical Center.
Acne (acne vulgaris, common acne) is a disease of the hair follicles of the face, chest, and back that affects almost all teenagers during puberty -- the only exception being members of a few primitive Neolithic tribes living in isolation. It is not caused by bacteria, although bacteria play a role in its development. It is not unusual for some women to develop acne in their mid- to late-20s.