The Biology of Acne

Normal Skin Function

Oil produced by the body normally protects the skin from environmental damage. The oil reaches the skin’s outer surface through pores, providing moisture and lubrication. Certain blockages, however, prevent the oil from reaching the surface, leading to the formation of acne. As a result, the oil becomes toxic to the skin, triggering the body to resist and causing the acne—sometimes called a pimple—to grow up to 20 times a skin cell pore’s normal size.

Direct Biological Causes

Most acne lesions, known as comedones, appear due to sebum, a secretion of the sebaceous gland that blocks hair follicles. Once they rupture, the follicular wall inflames and becomes irritated. The area also becomes infected by bacteria, called propionibacteria, causing the follicle to fill with pus and create, based on their size and location, pustules, papules and cysts. The body’s immune system responds with antibodies, leading to possible scar formation.

Underlying Biological Causes

The androgens—or sex hormones—responsible for most acne originate in the gonads and adrenal glands, which tend to be more active in youth. Although the exact nature of the interaction has not been identified, the relationship between high androgens and more active hormones has been determined. Testosterone, as well as the adrenal hormone known as DHEA, increases the size and level of secretion by the sebaceous glands.

Environmental Causes

Several factors can contribute to acne, including family history, stress, medications and diet. Stress increases the adrenal gland's production of hormones, which is already high among teenagers. Another major contributing factor, diet, increases hormone levels as well, especially certain dairy products, refined sugars and seafood. Use of some medications, especially those containing halogen-lithium, barbiturates and androgens, may increase acne because of their interaction with the body’s hormones.

Physical Responses

The growth of bacteria in the infected glands causes itching, and sufferers often complicate the condition by picking at or squeezing the acne. This action weakens the dermal layers, causing more bacteria to attack the affected area. It also creates more scarring, which impairs the skin’s ability to combat the acne. As a result, the sebaceous gland loses its path to the skin’s surface, allowing the acne to continue to grow beneath the skin.