Alopecia areata is a skin disorder that causes hair loss, usually in patches, most often on the scalp. Usually, the bald patches appear suddenly and affect only a limited area. The hair grows back within 12 months or less. For some people, however, the problem can last longer and be more severe, causing total baldness (alopecia totalis) or total loss of body hair (alopecia universalis).
The cause of alopecia areata is probably an autoimmune reaction. This means the body’s immune system incorrectly attacks the body’s own cells. In the case of alopecia areata, the cells under attack are in the hair follicles (structures that grow hair), especially follicles within the scalp.
Genetic (inherited) factors may play a role, too, particularly when the disorder strikes those under age 30. Almost 40% of people younger than age 30 with alopecia areata have at least one family member who has been diagnosed with the same disorder.
The risk of developing alopecia areata is unusually high in people who have asthma, hay fever, thyroid disease, vitiligo (a condition in which patches of skin lose their color), pernicious anemia and Down syndrome.
Although experts once believed episodes of alopecia areata could be triggered by stress, newer research has failed to prove that stress is a factor.
About 60% of people with alopecia areata experience the first episode of hair loss before age 20. It is usually followed by hair regrowth. However, it’s common for the problem to come back. New bald patches can develop at the same time older ones are regrowing hair.
In its most common form, alopecia areata causes small round or oval patches of baldness on the scalp. The area of bald skin looks smooth and normal. In most cases, there are no other scalp symptoms. Occasionally, there is mild itching, tingling, tenderness or a burning sensation in the affected area. Some people with alopecia areata also have abnormalities in the surface of their fingernails, such as tiny pits or dents, grooves, superficial splitting, or an abnormal area of redness.
DiagnosisIn rarer, more severe forms of the disorder, hair loss can involve the entire scalp or the entire body, including the eyebrows, eyelashes, beard, underarm hair and pubic hair (hair around the genitals).
Your doctor will usually be able to diagnose alopecia areata based on examination of the areas of your hair loss and your symptoms. To look for further evidence, your doctor may pull gently on the hairs near the edge of the bald area to determine whether these hairs come out very easily and to inspect them for any structural abnormalities of the root or shaft. If there is still doubt as to diagnosis, a small skin biopsy of your scalp may confirm the diagnosis. In a biopsy, a small piece of skin is removed and examined in a laboratory.
In most small patches of alopecia areata, the hair regrows within 6 to 12 months. However, it’s common for the problem to happen again.