Each hair on the human scalp has a defined life cycle. Each hair remains on the scalp for about four and one-half years. During that time, it grows at the rate of around one-half inch per month. The death of a single hair leads to the loss of that hair.

Normally, each lost hair is replaced. A new hair grows out of the hair follicle that once held the old, lost hair. If the scalp fails to produce a new hair, then the head of hair on that scalp will be minus one hair. If that should happen repeatedly, it would lead to thinning hair and appreciable hair loss. Hair loss is caused by the failure of the body to replace hairs, as they complete their life cycle.

Anything that can impede the creation of new hair can cause hair loss. Anything that can aid the creation of new hairs can promote hair replacement. Rogaine is a hair loss product that aids hair replacement. Rogaine increases the production of amino acids, the building blocks of the proteins in each hair. Supplied with the proper building blocks, a healthy hair should undergo its expected cycle of hair growth.

Rogaine represents one type of hair treatment. Use of Rogaine does not promise to give a man a permanent head of new hair. A man who wants a permanent solution to his hair loss problem needs to consider other hair treatments.

Medical hair restoration provides a man with a permanent head of hair. The hair restoration specialist redistributes the hair on the man's scalp. The best candidates for such hair restoration are those who have demonstrated signs of male pattern baldness.

Research has revealed the link between the levels of DHT and the appearance of male-patterned baldness. Medicines that block the transformation of testosterone into DHT have become an important component of the available techniques for hair restoration. . Such medicines contain the chemical finesteride. The finesteride molecule fits into a slot on the enzyme that catalyzes the production of DHT. In that way it prevents completion of all the biochemical steps that insure the production of DHT.

Some post-menopausal women exhibit an increase in the amount of testosterone in their body. Women who have rising testosterone levels can anticipate possible hair loss. Female hair loss has been linked to the appearance of high testosterone levels in post menopausal women.

Failed hair growth does not always produce hair loss on the scalp. Failed hair growth can lead to loss of hair in a man's beard or in the eyebrows of a man or a woman. Patchy hair growth on the scalp or face is called alopecia areata.

An understanding of failed hair growth requires an analysis of normal hair growth. Like all types of growth, hair growth requires cell division, leading to the production of new cells. New hair cells form within the hair bulb. If that bulb receives plenty of nourishment, then the new cells grow at the expected rate, and old dead hairs have the desired replacement.

Hair loss prevention begins with the provision of proper nourishment to the growing hair cells. Anything that slows the flow of blood to the hair bulb can hamper hair growth. Smoking reduces blood flow, and it has been linked to hair loss. A smoker would have little reason to use a hair loss shampoo, because his or her continued smoking would reverse the benefits provided by the use of such shampoos.

Hair restoration promises permanent hair replacement. Patients who pursue hair restoration can choose between laser hair restoration and traditional hair restoration. Both procedures call for placement of individual hairs in tiny indentations on the scalp. During a laser hair restoration, those indentations are made by a laser beam, rather than a surgical needle.

Of course, not everyone wants to face the prospect of surgery in order to gain a new head of hair. For that reason, scientists continue to pursue other hair loss treatments.