Acne is a common skin disease that affects tiny ducts in the skin where hair grows. These ducts are known as follicles. Acne occurs when the follicles become clogged and infected. This causes sores known as acne lesions, or pimples, to develop on and under the skin. Here we look at what is acne, and the cause of acne.

There are a number of factors that cause the follicles to become clogged and infected. One important factor is the overproduction of androgen. Androgen is a chemical, or male sex hormone, that both males and females normally produce. However, hormonal changes in the body during puberty, pregnancy, or the female menstrual cycle cause some people to produce higher than usual levels of androgen. Although scientists are unsure why, excess androgen stimulates the sebaceous oil glands inside the follicles to enlarge and manufacture excess amounts of oil called sebum. Whereas the normal production of sebum is necessary for healthy skin, excess sebum leads to the development of acne. Normally, the sebaceous oil glands produce small amounts of sebum, whose job it is to moisten and protect the skin. In order to do this, sebum works its way up through the hair follicles, where it washes away dead cells that accumulate in the follicles. Then sebum empties onto the skin through tiny openings in the follicles called pores. Here sebum protects the skin from bacteria that live on the skin by washing the bacteria away. However, when excess sebum is produced, it accumulates in the follicles rather than spilling out onto the surface of the skin. This occurs because the follicles are extremely small and narrow. Therefore, large volumes of sebum cannot pass through the follicles to the surface of the skin at the rate the sebum is produced. Instead, sebum becomes trapped in the follicles, where it mixes with dead skin cells, forms sticky plugs that block the pores, and prevents sebum from reaching the surface of the skin. As a result, the skin around the clogged follicles dries out. At the same time, since not every follicle becomes clogged, excess oil that spills onto the skin through unclogged follicles causes the skin to feel oily. Therefore, a person with acne may have dry skin around clogged follicles and oily skin everywhere else.

Clogged and infected hair follicles like this can cause sores, or acne lesions, to form under the skin.
Acne


Worse yet, without sebum to wash away bacteria on the skin, bacteria grow and multiply around the clogged follicles. Eventually, bacteria get inside the clogged follicles, where they mix with sebum and dead cells and cause an infection. This most commonly occurs on the parts of the body that have the largest sebaceous glands, such as the face, chest, neck, shoulders, upper back, and buttocks. The result is the development of one type of acne lesion known as a comedone.

Inflammation Makes Acne Worse
Unfortunately, the damage does not end there. Once bacteria enter the follicles, the immune system, which protects the body from infection and disease, reacts. Blood, rich with infection-fighting white blood cells, rushes to the area. As the infection worsens, pus and other powerful chemicals are also produced to combat the infection. This causes the infected area to become hot, red, swollen, and painful. Heat, redness, swelling, pain, and the presence of pus are all characteristics of inflammation, which in the case of acne appears on the skin in the form of papules, pustules, and cysts, other types of acne lesions.