What causes acne?The causes of acne are linked to the changes that take place as young people mature from childhood to adolescence (puberty). The hormones that cause physical maturation also cause the sebaceous (oil) glands of the skin to produce more sebum (oil). The hormones with the greatest effect on sebaceous glands are androgens (male hormones), which are present in females as well as males, but in higher amounts in males.

Sebaceous glands are found together with a hair shaft in a unit called a sebaceous follicle. During puberty, the cells of the skin that line the follicle begin to shed more rapidly. In people who develop acne, cells shed and stick together more so than in people who do not develop acne. When cells mix with the increased amount of sebum being produced, they can plug the opening of the follicle. Meanwhile, the sebaceous glands continue to produce sebum, and the follicle swells up with sebum.
In addition, a normal skin bacteria called P. acnes, begins to multiply rapidly in the clogged hair follicle. In the process, these bacteria produce irritating substances that can cause inflammation. Sometimes, the wall of the follicle bursts, spreading inflammation to the surrounding skin. This is the process by which acne lesions, from blackheads to pimples to nodules, are formed.

I wash my face several times a day. Why do I still get acne?Many people still believe that acne is caused by dirty skin. The truth is, washing alone will not clear up or prevent acne. Washing does, however, help remove excess surface oils and dead skin cells. Many people use all kinds of products, including alcohol-based cleansers, and scrub vigorously, only to irritate the skin further and worsen their acne. Washing the skin twice a day gently with water and a mild soap is usually all that is required. However, acne is actually caused by a variety of biologic factors that are beyond the control of washing. For that reason, you should use appropriate acne treatments for the acne.

Does stress cause acne?Stress is commonly blamed for the development of acne. Stress can have many physiologic effects on the body, including changes in hormones that may theoretically lead to acne. In some cases the stress may actually be caused by the acne lesions, not the other way around! If the acne is being treated effectively, stress is not likely to have much impact on the majority of people.

I never had acne as a teenager. Why am I now getting acne as an adult?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.