A rash, usually on the face, due to blockage and inflammation of glands in the skin
There are various types of acne. The most common form is acne vulgaris, which is the familiar rash that affects many teenagers, although it can occur at any age. Acne vulgaris is more common and tends to be more severe in males. The condition is triggered by hormonal changes at puberty and may appear as early as the age of 10. The rash usually subsides after adolescence but may persist after the age of 30. Acne can cause great psychological distress, and teenagers may feel especially self-conscious about their appearance.
More unusual forms of acne include occupational acne, which results from exposure to certain types of industrial oil, and drug-induced acne, which is caused by some prescribed drugs, such as corticosteroids.
Acne vulgaris is caused by the overproduction of sebum, an oily substance secreted by the sebaceous glands in the skin. Normally, the sebum drains into hair follicles and flows out through the follicle openings on the skin’s surface, thereby keeping the skin lubricated and supple. However, when the glands produce excess sebum, the follicles become blocked. If the sebum remains clogged in the follicle openings, it hardens and becomes dark, forming plugs called blackheads. In some cases, follicles are sealed by an excess of keratin, the tough, fibrous protein produced by the skin cells. The trapped sebum then hardens into white lumps, called white-heads, under the surface of the skin. In both types of blockage, the bacterium Propionibacterium acnes multiplies in the sebum, causing inflammation of the surrounding tissues.
Acne starting at puberty is thought to result from increased sensitivity to an-drogens (male sex hormones), which are present in both boys and girls and levels of which are raised during puberty. Androgens cause the sebaceous glands to increase their output of sebum. There may be a genetic factor since acne can run in families. The use of anabolic steroids to improve performance in sports may also raise androgen levels. Other causes of acne vulgaris include hormonal disorders such as Cushing’s syndrome, which is due to an excess of corticosteroid hormones.
Acne may become worse in times of stress. In girls, outbreaks may be affected by the hormonal fluctuations that occur during the menstrual cycle. The condition may also be exacerbated by the use of oil-based cosmetics.
Poor hygiene does not cause acne, but a build-up of oil and dead cells on the skin may result in blocked follicles and allow bacteria to multiply. You cannot catch acne from another person, and there is no evidence that fatty foods or sweets cause or aggravate acne.
Occupational acne is usually caused by long-term contact between the skin and oily clothes. The reasons for drug-induced acne are not known.
Acne vulgaris occurs in areas of skin that have a high density of sebaceous glands. At puberty, the hair, face, and upper trunk normally become greasy due to increased production of sebum. However, in people with acne, oiliness is excessive. Acne tends to appear on the face, but areas such as the upper back, centre of the chest, shoulders, and neck may also be affected. The disorder is usually more severe in winter and tends to improve in summer with increased exposure to sunlight. Lesions that are caused by occupational acne may appear on parts of the body that come into close contact with oily clothes. All forms of acne may produce some or all of the following types of lesion:
Small, firm whiteheads.
Red pimples, which often have yellow pus-filled tips.
Painful, large, firm, red lumps.
Tender lumps beneath the skin without obvious heads (cysts).
All these types of lesion may develop at any one time, but the severity of acne varies greatly from person to person. Deep-seated lesions may leave scars.
Self-help measures may help to clear up mild acne and prevent recurrence (see Controlling acne). Your doctor may also recommend a topical drug treatment, such as benzoyl peroxide or retinoid cream (see Retinoid drugs) to loosen keratin that is sealing the hair follicles. The doctor may also prescribe topical antibiotics (see Preparations for skin infections and infestations). Moderate acne can often be treated successfully with a low-dose oral antibiotic, such as tetracycline or erythromycin. However, treatment often needs to be continued for 6 months or more.
If these treatments fail, you may be referred to a dermatologist. He or she may prescribe isotretinoin, an oral retinoid that acts to loosen keratin and reduce sebum secretion. However, the use of isotretinoin during pregnancy is known to result in fetal abnormalities. For this reason, sexually active women should take the drug only if they are using a reliable contraceptive. Some women may be prescribed a specific contraceptive pill containing hormones that relieve acne by counteracting the action of androgens.
There is no immediate cure for acne. However, scarring may be prevented if treatment is started at an early stage. Individual acne cysts may be treated with corticosteroid injections. If acne has already left noticeable scars, you may wish to consult a cosmetic surgeon to discuss techniques to reduce the appearance of the scars, such as laser resurfacing or derma-brasion. In these procedures, the top layer of skin is removed, leaving a more even skin surface after the skin has healed.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.