MEDLINEplus Health Information: Return to home page   A service of the National Library of Medicine: Go to NLM home page
Search     Advanced Search    Site Map    About MEDLINEplus    Home
Health Topics: conditions, diseases and wellness Drug Information: generic and brand name drugs Dictionaries: spellings and definitions of medical terms Directories: doctors, dentists and hospitals Other Resources: organizations, libraries, publications, MEDLINE

Medical Encyclopedia

Disease     Injury     Nutrition     Poison     Special     Surgery     Symptoms     Tests

Alopecia areata with pustules
Alopecia totalis - back view of the head
Alopecia totalis - front view of the head
Alopecia, under treatment
Folliculitis, decalvans on the scalp
Ringworm, tinea capitis - close-up
Trichotillomania - top of the head
 
Overview   Treatment   

Hair loss

Alternative names:

alopecia; baldness; loss of hair

Definition:

The partial or complete loss of hair.

Considerations:

Baldness is determined by multiple genetic factors. It cannot be categorically stated that baldness follows the mother's line or anyone else's, or that it skips generations.

Both men and women lose hair density as they age. Men develop a typical pattern of baldness, associated with the presence of the male hormone testosterone. Men who do not produce testosterone (because of genetic abnormalities or castration) do not develop this pattern of baldness. The use of steroids during adolescence and young adulthood may accelerate the effects of testosterone on baldness. Women also develop a characteristic pattern of hair loss. See male-pattern baldness; female-pattern baldness.

Occurring most often on the scalp, alopecia usually develops gradually and may be all over (diffuse) or patchy.

Usually baldness is not caused by a disease but is genetic and permanent. Inherited or "pattern baldness" affects many more men than women. About 25% of men begin to bald by the time they are 30 years old, and about two-thirds are either bald or have a balding pattern by age 60.

On average, about 100 hairs are lost from the head every day. The average scalp contains about 100,000 hairs (blondes 140,000, brunettes 155,000 and redheads only 85,000).

Each individual hair survives for an average of 4.5 years, during which time it grows about half an inch a month. Usually in its 5th year, the hair falls out and is replaced within 6 months by a new one. Genetic baldness is caused by the body's failure to produce new hairs and not by excessive hair loss.

Common causes:

Note: There may be other causes of hair loss. This list is not all inclusive, and the causes are not presented in order of likelihood. The causes of hair loss can include unlikely diseases and medications. Furthermore, the causes may vary based on age and gender of the affected person, as well as on the specific characteristics such as location, quality, time course, aggravating factors, relieving factors, and associated complaints. Use the Symptom Analysis option to explore the possible explanations for hair loss, occurring alone or in combination with other problems.


Adam

The information provided herein should not be used for diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Copyright 2000 adam.com, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Health Topics | Drug Information | Dictionaries | Directories | Other Resources