Overview of Alopecia Areata

Alopecia areata is a type of hair loss that affects approximately 2 percent of the population—more than 4 million people in the United States. It affects both men and women, predominately children and young adults, but it can also develop in older adults. It usually starts out as smooth, small, round or oval patches of baldness that rapidly form on one side of the head.

The edges of the patches are usually studded with "exclamation point hairs." Erythema (inflammatory redness of the skin) may be present early on. For most people, the hair regrows within a year without treatment. The longer the time before hair regrows, the less likely it will regrow without treatment. Sometimes, the hair loss is permanent.

Causes of Alopecia Areata

Alopecia areata is an autoimmune disease (i.e., the immune system attacks the hair follicles). The follicles become very small, hair production slows, and there is a lack of visible hair for months or years. Yet, the follicles usually resume normal hair growth within a year.

Attacks of alopecia areata are often associated with other autoimmune conditions such as lupus and allergies. In about 20 percent of cases, the patient is related to someone who has or has had the disease.

Signs & Symptoms of Alopecia Areata

Alopecia areata usually appears as one or two bald patches on one side of the head, but also causes thinning all over the scalp. In the areas of baldness, the hairs are very short, broken, and narrow. They look like exclamation points and are sometimes called "exclamation point hairs." They can usually be seen with a hand lens.

Alopecia areata has a variable course. In some cases, the bald patches regrow within a few months or a year. Sometimes, extensive patchiness develops. Extensive alopecia has a poor prognosis.

There is about a 25 percent recurrence rate. All the hair from the scalp (alopecia totalis) or all the hair over the entire body (alopecia universalis) may be lost. Individuals may have patchy or even more diffuse hair loss on the scalp and/or body.

Fingernails or toenails can be affected. The nails are stippled with rows of what look like tiny pin pricks. Rarely, the nails may be entirely distorted.

Diagnosis of Alopecia Areata

The hair is sometimes biopsied to confirm the diagnosis. A biopsy involves taking a sample of hair and looking at it under a microscope to determine if there are lymphocytes (immune system cells) inside the hair follicles.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 02 Feb 2001

Last Modified: 17 Sep 2015