Male pattern baldness is the most common type of hair loss in men. It usually follows a typical pattern of receding hairline and hair thinning on the crown, and is caused by hormones and genetic predisposition.

Hair grows about an inch every couple of months. Each hair grows for 2 to 6 years, remains at that length for a short period, then falls out. A new hair soon begins growing in its place. At any one time, about 85% of the hair on your head is in the growing phase and 15% is not.

Each hair sits in a cavity in the skin called a follicle. Baldness in men occurs when the follicle shrinks over time, resulting in shorter and finer hair. The end result is a very small follicle with no hair inside. Ordinarily, hair should grow back. However, in men who are balding, the follicle fails to grow a new hair. Why this occurs is not well understood, but it is related to your genes and male sex hormones. Even though the follicles are small, they remain alive, suggesting the possibility of new growth.

The typical pattern of male baldness begins at the hairline. The hairline gradually recedes to form an "M" shape. The existing hair may become finer and shorter. The hair at the crown also begins to thin. Eventually the top of the hairline meets the thinned crown, leaving a horseshoe pattern of hair around the sides of the head.

Hair loss in patches, diffuse shedding of hair, breaking of hair shafts, or hair loss associated with redness, scaling, pain, or rapid progression could be caused by other conditions.

Classic male pattern baldness is usually diagnosed based on the appearance and pattern of the hair loss. Any atypical hair loss may be caused by other medical disorders. A skin biopsy or other procedures may be needed to diagnose other disorders that cause loss of hair.

Hair analysis is not accurate for diagnosing nutritional or similar causes of hair loss. However, it may reveal substances such as arsenic or lead.

Treatment is not necessary if you are comfortable with your appearance. Hair weaving, hairpieces, or change of hairstyle may disguise the hair loss. This is usually the least expensive and safest approach for male baldness.

There are two main drugs used to treat male pattern baldness:

• Minoxidil (Rogaine) -- a solution that you apply directly to the scalp to stimulate the hair follicles. It slows hair loss for many men, and some men grow new hair. The previous degree of hair loss returns when you stop applying the solution.
• Finasteride (Propecia, Proscar) -- a prescription pill that inhibits the production of the male hormone dihydrotestosterone. Like minoxidil, you are more likely to have slower hair loss than actual new hair growth. In general, it is somewhat more effective than minoxidil. The previous degree of hair loss returns when you stop taking the drug.

Hair transplants consist of removing tiny plugs of hair from areas where the hair is continuing to grow and placing them in areas that are balding. This can cause minor scarring in the donor areas and carries a modest risk for skin infection. The procedure usually requires multiple transplantation sessions and may be expensive. Results, however, are often excellent and permanent.

Suturing hair pieces to the scalp is not recommended. It can result in scars, infections, and abscess of the scalp. The use of hair implants made of artificial fibers was banned by the FDA because of the high rate of infection.

Male pattern baldness does not indicate a medical disorder, but it may affect self-esteem or cause anxiety. The hair loss is usually permanent.

• Psychological stress
• Loss of self-esteem due to change in appearance

Call your doctor if:

• Your hair loss occurs in an atypical pattern -- rapid hair loss, diffuse shedding, hair loss in patches, or breaking of hair shafts.
• Your hair loss is accompanied by itching, skin irritation, redness, scaling, pain, or other symptoms.
• Your hair loss begins after starting a medication.
• You want to attempt to treat your hair loss.

There is no known prevention for male pattern baldness.

Cummings CW, Flint PW, Haughey BH, et al. Otolaryngology: Head & Neck Surgery. 4th ed. St Louis, Mo; Mosby; 2005.

Habif TP. Clinical Dermatology. 4th ed. St. Louis, Mo: Mosby; 2004.