Acne is a chronic, inflammatory skin condition that causes spots and pimples, especially on the face, shoulders, back, neck, chest, and upper arms. Whiteheads, blackheads, pimples, cysts, and nodules are all types of acne.I It commonly occurs during puberty, when the sebaceous glands activate, but it can occur at any age. It is not dangerous, but it can leave skin scars. The glands produce oil and are stimulated by male hormones produced by the adrenal glands in both males and females. 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.