An average person has approximately 90,000 to 150,000 scalp hairs. Natural blondes tend to have the most hairs (averaging 140,000) while brunettes and redheads fall on the lower end of the normal scale (averaging 105,000 and 90,000 hairs respectively).

All scalp hair continually cycles through a lengthy growth period followed by a short resting phase and then loss. During the growth period, which lasts two to six years, a hair emerges from a follicle and lengthens by roughly a half-inch per month. It then enters a resting phase, which lasts just two to three months. After the hair is lost, a new hair emerges from the same follicle within six months.

It is normal to lose 50 to 150 hairs per day. True hair loss, or alopecia, occurs when an excessive number of hairs are lost over a short period of time, or when hairs are not replaced in a timely, full or healthy fashion.

There are many medical causes for true hair loss:

• Androgenetic Alopecia, more often called male or female pattern hair loss (baldness)
• Alopecia Areata
• Burns & Scars
• Cancer & Cancer Treatments (chemotherapy)
• Diabetes
• Hormonal Imbalances, including those caused by pregnancy or thyroid disease
• Infection
• Lupus
• Malnutrition, including iron deficiency
• Medications & Medical Treatments
• Stress, Trichotillomania & Other Illness

Information on this page, provided as a service by Peggy Knight Solutions, draws upon information from the following sources: the American Academy of Dermatology, the American Academy of Family Physicians, the American Medical Association, and the U.S. National Library of Medicine and the National Institutes of Health.