Alopecia areata is an autoimmune disorder that causes hair loss. Alopecia areata causes the immune system to produce antibodies that attack the body's healthy hair follicles. Hair loss may be acute, or it may recur.

Hair Loss
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The cause of alopecia areata is unknown. It is likely due to a combination of genetic and environmental factors. It most typically affects patches of the scalp. Variations of alopecia areata can cause hair loss on the entire scalp, in men's beards, or over the entire body.