Acne occurs most commonly during adolescence, and often continues into adulthood. In adolescence, acne is usually caused by an increase in testosterone, which people of both genders accrue during puberty.^[3] For most people, acne diminishes over time and tends to disappear — or at the very least decrease — after one reaches one's early twenties. There is, however, no way to predict how long it will take to disappear entirely, and some individuals will carry this condition well into their thirties, forties, and beyond.^[4]

Some of the large nodules were previously called "cysts" and the term nodulocystic has been used to describe severe cases of inflammatory acne.^[5] The "cysts," or boils that accompany cystic acne, can appear on the buttocks, groin, and armpit area, and anywhere else where sweat collects in hair follicles and perspiration ducts.^[6] Cystic acne affects deeper skin tissue than does common acne.^[7]

Aside from scarring, its main effects are psychological, such as reduced self-esteem^[8] and, according to at least one study, depression or suicide.^[9] Acne usually appears during adolescence, when people already tend to be most socially insecure. Early and aggressive treatment is therefore advocated by some to lessen the overall impact to individuals.^[8]