What causes it?

Hair grows from specialised cells called hair follicles. In some people, androgens (male sex hormones) cause the hair follicles to shrink and cease to produce hair as normal. This sensitivity of the hair follicles to androgens is genetic and the main cause of male pattern baldness.

The cause of alopecia areata is unknown but it may be an auto-immune disorder. The hair follicles are usually not permanently damaged and in many cases the hair grows back in a few months. One in 5 cases are genetic. A person with alopecia areata is more likely to have or to develop other autoimmune conditions such as thyroid disease, diabetes and vitiligo (a condition that produces white patches on the skin). Occasionally all body hair may be lost (alopecia universalis). The chance of hair regrowth is poorer for people with alopecia universalis and extensive alopecia areata.

Other causes of localised hair loss include:

• Fungal infection of the scalp such as ringworm
• Overuse of hot comb or hair dryer
• Hairstyles that pull on the hair
• Deliberately pulling out of the hair (trichotillomania)
• Permanent skin damage from burns or serious skin diseases
• Radiation therapy

Generalised hair loss result from:

• Chemotherapy
• Stress (including bereavement or stress of major surgery)
• Severe illness
• Thyroid disorders
• Pregnancy
• Post-partum (after having a baby)
• Some prescription drugs and high doses of Vitamin A

Should I see my doctor?

If you are concerned that you may be developing alopecia, visit your doctor. Your scalp and skin will be examined. A skin scraping may be taken to check for a fungal infection.