Hair Loss

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Medical Author:

Gary W. Cole, MD, FAAD

Gary W. Cole, MD, FAAD

Dr. Cole is board certified in dermatology. He obtained his BA degree in bacteriology, his MA degree in microbiology, and his MD at the University of California, Los Angeles. He trained in dermatology at the University of Oregon, where he completed his residency.

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Medical Editor:

Jerry R. Balentine, DO, FACEP

Jerry R. Balentine, DO, FACEP

Dr. Balentine received his undergraduate degree from McDaniel College in Westminster, Maryland. He attended medical school at the Philadelphia College of Osteopathic Medicine graduating in1983. He completed his internship at St. Joseph's Hospital in Philadelphia and his Emergency Medicine residency at Lincoln Medical and Mental Health Center in the Bronx, where he served as chief resident.

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• Hair Loss Overview
• Hair Loss Causes
• Hair Loss Symptoms and Signs
• When to Seek Medical Care
• Hair Loss Diagnosis
• Hair Loss Treatment
• Self-Care at Home
• Medical Treatment
• Hair Loss Surgery
• Follow-up
• Hair Loss Prevention
• Hair Loss Prognosis
• Hair Loss Pictures
• Synonyms and Keywords
• Authors and Editors
• Read more on Hair Loss from Healthwise
• Hair Loss FAQs

The loss of hair (alopecia) is a natural phenomenon in all hair-baring animals that normally occurs during the hair growth cycle. It is estimated that most individuals (assuming they have a full head of hair) lose about 100 scalp hairs over a 24-hour period. Hair loss can become a cosmetic problem when it occurs in the wrong place at the wrong time in the wrong individual. True hair loss should be distinguished from damage to the hair shaft, which may cause breakage close to the scalp. This sort of damage is most often caused by exogenous chemicals used to alter the physical characteristics of the hair shaft (hair dye, etc.), but certain genetic diseases can alter its strength and durability.

• Physicians divide cosmetically significant hair loss into two categories.



1. Scarring alopecia: This sort of irreversible hair loss is characterized by damage to the underlying skin which results in scarring that destroys the hair follicle and its potential for regeneration. A simple visual examination is usually sufficient to diagnose this problem, although occasionally a biopsy may be necessary. Certain skin diseases as well as physical trauma produce this sort of damage.

2. Non-scarring alopecia: This potentially reversible type of hair loss is very common and can be due to many causes, including certain diseases, drugs, aging, diet, as well as a genetic predisposition for hair loss called androgenetic alopecia (common balding).


• There are three cycles of hair growth: growing (80% of follicles), resting, and shedding. In human hair, each follicle cycles at its own individual rate as opposed to most animals, where these cycles change with the season, and all hairs are in the same part of the cycle at the same time. This is why animals grow a thicker coat in the fall and shed most in the spring and why human beings do not shed.



• Unlike most animals, in humans, each hair has its own pattern of growing, resting, and shedding.



• Each person sheds hair and regrows hair every day.



• When this balance is disturbed and more hairs are shed than are regrown, alopecia or hair loss results.

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