The average scalp contains about 100,000 hairs and we all will normally lose about 100 hairs every day. Individual hairs have a life-span of approximately four and one half years, growing roughly one half inch a month. Both men and women tend to lose hair thickness and amount as they age. Baldness is not typically caused by a disease; but by the aging process, heredity and testosterone.
Male pattern baldness is characterized by a receding hairline and thinning around the crown with eventual bald spots. This is a genetic condition and typically hair loss begins by the age of 30, and often as early as the teens. Male pattern baldness seems to need the male hormone testosterone; studies have shown that men who do not produce testosterone do not develop this pattern of baldness. Male hormones tend to increase in women after menopause causing some women to develop a particular pattern of baldness. Age and genetics also play a role in female pattern baldness. The pattern of baldness in women is different from that of men; it involves thinning of the hair throughout the scalp, with the front hairline generally staying intact.
There are many other causes of hair loss, most of which are temporary. Physical or emotional stress may cause 50 to 75% of the hair throughout the scalp to shed; this condition is known as Telogen effluvium. You may not notice the hair loss until weeks or even months after the episode of stress and the hair loss will decrease over six to eight months. There are many causes for this type of hair loss among them is high fever or severe infection, major surgery or blood loss, or a severe emotional stress. Certain medications can cause hair loss; retinoids, birth control pills, beta-blockers, antidepressants and calcium channel blockers are a few. Crash diets, especially those that do not contain enough protein can cause hair loss. Excessive shampooing and blow-drying may even be the cause of excessive hair loss.
Depending on the type of hair loss, there are treatments available. If a medication is causing the problem, your doctor may be able to prescribe an alternative; correcting a hormonal imbalance may prevent further hair loss. There are medications that may help to slow or prevent the development of common baldness; one of which is available without a prescription. If medications do not work, there are hair replacement procedures that use existing hair to partially or completely reduce the appearance of baldness.