Alopecia areata is a disease of unknown cause that can result in hair loss on any part of the body. A common pattern of patchy scalp hair loss is shown in these photos:

Loss of hair on a man’s scalp due to alopecia areata.

Diffuse loss of scalp hair in a teen-age girl due to alopecia areata.

(Photos used in this discussion are with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides and the Sulzberger Institute for Dermatologic Education]

Loss of scalp hair and eyebrows may occur at about the same time. Hair loss due to alopecia areata is not always permanent but may come and go in the same areas. It often resolves within two years. Topical or injected steroids can sometimes control the disease process, especially in children and teen-agers. The condition should not be self-treated. A person with alopecia areata should be under the care of a dermatologist.

Telogen effluvium is seen more often in women than in men. It is the result of an increased percentage of scalp hairs going into the telogen (resting) phase of hair growth and loss. A typical pattern of telogen effluvium is overall thinning of scalp hair, without any prominent bald patches. Common causes of telogen effluvium are the use of oral contraceptives for many years, hormonal changes after childbirth, chronic emotional or physical stress, and crash dieting. The condition usually resolves slowly, beginning six to 12 weeks after the cause is removed. There is no medical treatment for telogen effluvium.

Traction alopecia is hair loss due to constant tension pulling hair away from the scalp. Common causes of traction alopecia are braiding and corn-rowing as shown in this photo:

Traction alopecia in a young girl due to corn-rowing of hair.

Men can have traction alopecia when a hairpiece attached to permanent hair exerts constant tension against the scalp. A person with traction alopecia should consult a dermatologist or dermatologic surgeon to determine what to do about hair loss.

Trichotillomania is a compulsive plucking of scalp hair that can result in permanent hair loss. The person with trichotillomania frequently plucks and re-plucks hair from the same area of the scalp. Permanent hair loss due to trichotillomania is shown in this photo:

Hair loss due to permanent scarring of scalp by compulsive hair plucking—trichotillomania.

When hair loss is due to trichotillomania, hair restoration is of little use until the compulsive disorder is addressed by psychological counseling.

Scarring alopecia is loss of hair due to scalp scarring by disease or injury. A number of autoimmune and infectious diseases can scar the scalp. Burns are a common cause of traumatic scarring. A dermatologic surgeon should be consulted about the possibility of surgical hair restoration. In cases of very severe scarring, a wig may be necessary.