Dermatology A to Z
What Causes Alopecia Areata?
In alopecia areata, round patches of hair loss appear suddenly. A barber or hairdresser often discovers the hair loss. The hair loss may not be limited to the scalp. Eyebrows, eyelashes, facial hair, and body hair may also be affected. The hair is lost when the hair-growing tissue stops making hair, and the hair then falls out from the root. Why this happens is a mystery. Alopecia areata is not contagious, not caused by foods, and not the result of nervousness. It sometimes runs in families.
Alopecia areata has three stages. First, there is sudden hair loss. Then the patches of hair loss may enlarge. Last, new hair grows back. This takes months-sometimes more than a year. The course of alopecia is unpredictable. In most individuals, there is only one or a few areas of hair loss. In a small number of individuals, all the hair on the scalp may fall out (a condition called alopecia totalis). In a very few cases, all the hair on the body may be lost (alopecia universalis). Most of the time the hair will regrow. Biopsy of the areas of hair loss shows an inflammation around the hair-forming follicles. Alopecia areata appears to be a condition in which the immune system begins to attack hair follicles as foreign (an autoimmune condition).
There are many other causes of hair loss. Your doctor may order some screening tests to rule out underlying thyroid disease, hormonal disturbances, anemia and even syphilis or other infectious diseases. Individuals who have recently been severely ill, hospitalized, undergone surgery, or even a recent pregnancy sometimes lose their hair weeks after the event. This condition is called telogen effluvium. Thinning of hair is a normal physiologic event and accompanies aging. Heredity plays a role in many cases of baldness and severe hair loss.
The hair usually grows back by itself, but slowly. Sometimes the new hair is temporarily gray or white, but after a while, the original color usually returns. Injecting a corticosteroid preparation into the area of hair loss can often speed up the natural regrowth of hair. The steroid is injected into the skin. It acts only in the area where it has been injected. Unfortunately, there is no way of preventing new areas of hair loss. However, if new areas of hair loss appear, injecting steroids into those areas may stop the loss and stimulate regrowth more quickly. The area of hair loss is usually injected at 4-6 week intervals. Unfortunately, individuals with extensive hair loss and loss of body hair and eyebrows have the least chance for complete regrowth.
There are many other treatments that have been described and tried. These include irritating topical agents, phototherapy, and oral medications. None have reliably been shown to work and your physician does not recommend you attempt them out of desperation to regain your hair. In the worst cases, it may be necessary to obtain a wig temporarily or permanently.