Hair loss of any sort is called alopecia—be it normal male-pattern baldness (androgenic alopecia, or AGA) that commonly occurs as men age, or abnormal hair loss associated with certain diseases, hormonal disturbances, or treatments such as chemotherapy. There are two general types of alopecia: scarring and nonscarring.

In scarring alopecia, the hair follicles that support the hair shaft are destroyed by an underlying condition, so that hair loss is irreversible. In nonscarring alopecia (which includes AGA and alopecia areata), the follicles are preserved, so that regrowth of lost hair remains a possibility. Alopecia has many causes, all of which may affect both sexes.

What Causes Hair Loss?

  • An inherited change that normally occurs with age (AGA).
  • Following childbirth, women may experience a several-month-long period of increased hair shedding (telogen effluvium).
  • An autoimmune response (alopecia areata).
  • Bacterial or fungal infections (when severe, may cause scarring and permanent hair loss).
  • Cutaneous (skin) discoid lupus or scleroderma (scarring alopecia).
  • Chemotherapy drugs (diffuse hair loss with temporary complete baldness).
  • Other drugs including corticosteroids, testosterone, heparin, occasionally cholesterol-lowering drugs, and antithyroid agents (increased rate of hair shedding).
  • Malnutrition (especially inadequate protein intake), digestive malabsorption, anorexia nervosa, rapid weight loss, or chronic illness.
  • Rare congenital and developmental defects.
  • Chemical and physical agents, such as acids, bleach, burns, freezing, or radiation (including x-rays and radiotherapy for cancer).
  • Poisoning with toxic levels of arsenic, bismuth, boric acid, and vitamin A.
  • Regular use of a blow dryer, flat iron and similar devices may damage hair.

Symptoms of Hair Loss

  • AGA in men: hairline recession at the temples and thinning hair over the vertex; progressive merging of these areas
  • AGA in women: thinning of hair on top of head with a widened partline; unlike male pattern hair loss, frontal hair margins almost always preserved
  • Alopecia areata (a common type of autoimmune hair loss usually first appearing in children or young adults): coin-size areas of temporary, often recurring, hair loss on the head or elsewhere; rarely, total scalp hair or body hair loss

Prevention of Hair Loss

  • Hair shaft breakage may be prevented by not over-processing hair with coloring agents or procedures such as permanent waving or straightening.

Diagnosis of Hair Loss

  • Alopecia can usually be diagnosed by examination of the characteristic patterns of hair loss.
  • More extensive medical tests are warranted when a pathological condition is thought to cause hair loss.
  • Scalp biopsy can be helpful to make or confirm a diagnosis of hair loss and also to help develop a treatment plan.

How to Treat Hair Loss

  • Any underlying medical condition causing alopecia needs to be diagnosed and treated.
  • Treatment for AGA is not necessary, although a number of methods can restore cosmetic appearance.
  • The topical medication minoxidil often slows the loss of hair and may lead to regrowth of some hair.
  • Men may benefit from the prescription oral drug finasteride, which causes some hair growth in most users. (Because finasteride may cause birth defects, it is not prescribed for women).
  • Hair gels, permanent waves, wigs, hair weaves, hair transplants, or surgery to reposition existing portions of the scalp are other methods to consider.
  • Topical or injectable cortisone medications may be performed to treat certain types of hair loss.
  • Hair transplantation, which utilizes dermatologic surgery to move some existing scalp hair to bald or thinning parts, may be performed for permanent hair replacement.

When to Call a Doctor

  • Although it is normal to shed 50 to 100 hairs a day, consult your doctor or dermatologist if you notice persistent excess shedding, which may be a symptom of an underlying medical disorder.
  • See your doctor if a scalp infection is suspected. Infection can lead to permanent hair loss.


Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference

Simeon Margolis, M.D., Ph.D., Medical Editor

Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at

Published: 24 Aug 2011

Last Modified: 08 Jan 2015