What causes alopecia areata?
Alopecia is another name for hair loss. Alopecia areata is an autoimmune disease that happens when your immune system mistakenly attacks a part of your body. When you have alopecia areata, the cells in your immune system surround and attack your hair follicles (the part of your body that makes hair).
Hair follicles are the structures in skin that form hair. While hair can be lost from any part of the body, alopecia areata usually affects the head and face. However, there are three main types; alopecia areata, alopecia totalis and alopecia universalis.