I never had acne as a teenager. Why am I now getting acne as an adult? - A to Z Dermatology
Usually, acne begins at puberty and is gone by the early 20s. In some cases, acne may persist into adulthood. Such types of acne include severe forms that affect the body as well as the face (which afflict males more than females) and acne associated with the menstrual cycle in women. In other cases, acne may not present itself until adulthood. Such acne is more likely to affect females than males.
There are several reasons for this. As females get older, the pattern of changes in hormones may itself change, disposing sebaceous glands to develop acne. Ovarian cysts and pregnancy may also cause hormonal changes that lead to acne. Some women get acne when they discontinue birth control pills that have been keeping acne at bay. Sometimes young women may wear cosmetics that are comedogenic-that is, they can set up conditions that cause comedones to form.