Acne Vulgaris: Overview and Risk Factors

Acne is the most common skin disorder in the United States, affecting more than 17 million Americans. Most adolescents in Western countries experience some degree of acne, which generally resolves as sex hormone concentrations decline with time. Some cases, however, persist into adulthood or begin in adulthood.

Common acne, as it appears in adolescents, is associated with many factors, including genetics, hormonal abnormalities, and clogged skin follicles. Increased production of sex hormones during puberty leads to growth of the skin glands and increased lubrication of the skin, which is optimal for bacterial growth. Under these conditions, the Propionibacterium acnes bacteria grows and causes inflammation that results in the characteristic acne appearance.

Acne most commonly affects areas of the body with the greatest number of skin glands. These include the face, upper back, neck, chest, and upper arms. Scarring can also occur, particularly in individuals with darker complexions.

Risk Factors

• Cosmetics: Skin and hair products that contain oils or dyes can exacerbate acne lesions. Water–based cosmetics are less likely to cause acne.
• Repetitive skin trauma: Rubbing (even with cleansing agents), scrubbing, or restrictive clothing (e.g., bra straps, helmets, turtlenecks) can worsen acne.
• Environmental exposures: Humidity and sweating can worsen acne. Exposure to certain chemicals (e.g., dioxin and other halogenated hydrocarbons) that are found in herbicides and other industrial products can cause severe acne and scarring.
• Drugs: Certain drugs are likely to cause acne, including steroids, phenytoin, isoniazid, disulfiram, lithium, and B vitamins.
• Diet: Western diets, and milk in particular, have been linked to acne (see Nutritional Considerations).
• Climate: Humidity and heavy sweating may lead to acne.
• Genetics: Genetics likely play a role in the manifestation of acne, especially in persistent and late–onset cases.
• Stress: Stress is believed to be associated with acne exacerbations, but further study is required to establish this connection.