Common Causes of Hair Loss
August 2022
in “
JAMA
”
alopecia nonscarring alopecia patterned hair loss androgenetic alopecia dihydrotestosterone telogen effluvium thyroid disease vitamin deficiencies alopecia areata autoimmune disorder minoxidil finasteride low-level laser light therapy corticosteroid injections Janus kinase inhibitors DHT Rogaine Propecia LLLT JAK inhibitors
TLDR Hair loss can be caused by hormones, illness, autoimmune disorders, or vitamin deficiencies, and treatments vary depending on the type.
Hair loss, or alopecia, is categorized as scarring or nonscarring, with the latter being the most common. Nonscarring alopecia can be patterned, diffuse, or focal. Patterned hair loss, such as androgenetic alopecia, involves thinning of hair at the front, top, and sides of the scalp due to exposure to the male sex hormone dihydrotestosterone. Diffuse hair loss, like telogen effluvium, involves loss of hair evenly across the scalp due to factors like illness, surgery, thyroid disease, or vitamin deficiencies. Focal hair loss, such as alopecia areata, involves loss of hair in patches due to an autoimmune disorder. Treatments for these types of hair loss include topical application of minoxidil, oral medication finasteride, low-level laser light therapy, and corticosteroid injections. For telogen effluvium, treatment of the underlying cause is recommended. Severe alopecia areata may benefit from a class of oral medications called Janus kinase inhibitors.
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