Alopecia areata is a type of hair loss that occurs when your immune system mistakenly attacks hair follicles , which is where hair growth begins. The damage to the follicle is usually not permanent. Experts do not know why the immune system attacks the follicles.
500,000 persons in the US
Typical Age of onset
Mainly under age 30, but can occur in older persons
Patchy hair loss, mostly on the scalp but can involve eyebrows, eyelashes, beards
“Exclamation mark” hairs that get narrower at the bottom, like an exclamation mark.
Widespread hair loss
Finger- and toe-nails have dents, white spots, and roughness