In cases of alopecia areata, hair  tends to pull out more easily along the edge of the patch where the follicles are already being attacked by the bodys immune system than away from the patch where they are still healthy.Nails may have pitting or trachyonychia. Causes
Alopecia areata is thought to be a systemic autoimmune disorder in which the body attacks its own anagen hair follicles and suppresses or stops hair growth. For example, T cell lymphocytes cluster around affected follicles, causing inflammation and subsequent hair loss. Hair follicles in a normal state are thought to be kept secure from the immune system, a phenomenon called immune privilege. A breach in this immune privilege state is considered as the cause of alopecia areata. A few cases of babies being born with congenital alopecia areata have been reported.Alopecia areata is not contagious. It occurs more frequently in people who have affected family members, suggesting heredity may be a factor. Strong evidence of genetic association with increased risk for alopecia areata was found by studying families with two or more affected members. This study identified at least four regions in the genome that are likely to contain these genes. In addition, alopecia areata shares genetic risk factors with other autoimmune diseases, including rheumatoid arthritis, type 1 diabetes, and celiac disease.
Some other medications that have been used are minoxidil, Elocon (mometasone) ointment (steroid cream), irritants (anthralin or topical coal tar), and topical immunotherapy ciclosporin, sometimes in different combinations. Topical corticosteroids frequently fail to enter the skin deeply enough to affect the hair bulbs, which are the treatment target, and small lesions typically also regrow spontaneously. Oral corticosteroids may decrease the hair loss, but only for the period during which they are taken, and these medications can cause serious side effects. No one treatment is effective in all cases, and some individuals may show no response to any treatment. Few treatments have been well evaluated. A 2008 meta-analysis of oral and topical corticosteroids, topical ciclosporin, photodynamic therapy, and topical minoxidil showed no benefit of hair growth compared with placebo, especially with regard to long-term benefits. For more severe cases, recent studies have shown promising results with the individual use of the immunosuppressant Methotrexate or adjunct use with corticosteroids. However, as relapse of the condition may occur long-term treatment is recommended.When alopecia areata is associated with celiac disease, treatment with a gluten-free diet allows for complete and permanent regrowth of scalp and other body hair in many people, but in others, remissions and recurrences are seen. This improvement is probably due to the normalization of the immune response as a result of gluten withdrawal from the diet.In June 2022, the U.S. Food and Drug Administration (FDA) authorized baricitinib for the treatment of severe alopecia areata.