There are many types of hair loss. It is often categorized according to when it takes place during the hair growth cycle: anagen, catagen, and telogen.
Androgenetic alopecia is inherited hair loss. In this type of hair loss, the growth (anagen) cycle becomes shorter and shorter. The hair follicles sprout hairs that are thinner than normal. The hairs become thinner and thinner, and eventually the follicles wither away.
Alopecia areata is a type of hair loss that is caused when the immune system mistakenly attacks hair follicles. This type of hair loss begins to get worse when hair follicles enter the rest (telogen) phase too soon.
Telogen effluvium has many causes. In this type of hair loss, large numbers of hairs enter the resting phase (telogen), which causes shedding and thinning. Usually no more than 50% of the hair is affected, and hair loss may occur up to 3 months after the event that causes it.footnote 1Causes include:
Two types of hair loss not related to the hair growth cycle are trichotillomania and traction alopecia.
Habif TP (2010). Hair diseases. In Clinical Dermatology: A Color Guide to Diagnosis and Therapy, 5th ed., pp. 913-935. Edinburgh: Mosby Elsevier.
ByHealthwise Staff Primary Medical Reviewer Adam Husney, MD - Family Medicine Martin J. Gabica, MD - Family Medicine Specialist Medical Reviewer Ellen K. Roh, MD - Dermatology
Current as ofOctober 6, 2017
Current as of:
October 6, 2017
Adam Husney, MD - Family Medicine & Martin J. Gabica, MD - Family Medicine & Ellen K. Roh, MD - Dermatology
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