Hair does not really serve any important function since a person can certainly live without it! Yet, our hair and how it looks is a very important part of our self-image. So when a person loses his hair, it is a disturbing event. The life cycle of a single hair can be divided into a period of active growth, lasting several years, and a resting stage, which lasts 60 to 90 days. Of the normal scalp's 100,000 hairs, as many as 15 percent are in the resting mode, soon to be lost at the rate of about 75 hairs per day (hardly noticeable to people). The rate of hair loss does increase dramatically when the growing hair follicle is subjected to different types of internal stress, such as high fever, severe flu, surgery, crash diets, and certain medications. Most abnormal hair loss in younger people is caused by one of five conditions: tinea capitis, alopecia areata, traction alopecia, trichotillomania, and telogen effluvium. (Dermatologists love fancy names for their diseases!)

Tinea capitis or "ringworm" is a common cause of hair loss. The condition is caused by a fungus (not a worm) that invades the hair shaft and causes the hairs to break. The bare patch of hair loss is often round and the scalp takes on a black-dot stubble appearance from hair shafts broken off at the surface. There may also be mild scalp itching and scaling. The condition is transmitted by contact from one infected person to another by sharing combs, brushes, hats, barrettes, pillows and bath towels. Minor bruising of the scalp occasionally provides an entry for the microscopic fungus. Ringworm of the scalp is not dangerous. Without treatment, however, the hair loss can be considerable and some will develop a boggy tender swelling of the scalp known as a kerion.

Tinea capitis is treated with an oral antifungal medication called griseofulvin, usually taken for up to eight weeks. Selenium sulfide shampoo, used twice a week, has been shown to shorten the course of tinea capitis. Topical antifungal creams usually do not help in killing the fungus and shaving the hair or giving the person a close haircut is unnecessary. Even though the infection is still visible, a person with tinea capitis may return to school after oral medication is started and the scalp receives at least one washing with shampoo.

Alopecia areata (alopecia means "hair loss," areata means "in patches") is another common form of patchy hair loss. The typical story is the sudden appearance of one or more totally bald areas in the scalp. The person with this condition loses hair in circular patches sometimes up to two inches in diameter. The hair at the borders of these patches is loose, but the peach-colored scalp looks and feels normal, without scaling or inflammation. There may be just a few patches of hair loss or a total absence of body hair. Alopecia areata is not life-threatening, and people who have it are otherwise healthy. Why the hair falls out from the roots is still a mystery. What is known is that the condition is not contagious, caused by foods, or the result of nervousness or psychological stress. In 20 percent of cases another family member has been affected. Some patients with this condition will also develop a grid-like pitting of the nails.

Fortunately, more than 80 percent of young people with alopecia areata grow new hair back within 12 months. Oddly, the new hair may temporarily be white, but eventually the hair returns to its natural color. Because the hair loss can sometimes be psychologically devastating for people, dermatologists have tried many different medications in an attempt to stimulate new hair growth. Treatments sometimes involve cortisone injections into the hair follicles.

Traction alopecia, or physical damage to the hair, is another common cause of hair loss, particularly in girls. The human hair is quite fragile and really does not respond well to the many physical and chemical assaults it has to endure in the name of beauty. Constant teasing, fluffing, washing, curling, blow drying, hot combing, straightening and bleaching can do a number on the fragile hairs, causing them to fall out, especially those by the hair line and along the front and sides. Styles that apply tension to the hair, such as tight ponytails, braiding, barrettes, and permanent waving can also damage the hair.

Treatment is to handle the hair gently, as little as possible, and use natural hair styles. The hair will usually return, but regrowth can be slow. Injured hair follicles do not heal quickly and often take three or more months before they are back to their growing phase.

Trichotillomania is the compulsion to pull out one's own hair. It results in irregular patches of incomplete hair loss, mainly on the scalp, but may involve the eyebrows and eyelashes as well. The habit of pulling out one's hair is usually practiced in bed before falling asleep or when the person is studying or watching television. Interestingly, people are usually not aware of the habit and frequently find it hard to believe that they would pull out their own hair. Affected areas of hair loss often appear on the left side of right-handed people and on the right side of left-handed people. Most cases of trichotillomania resolve spontaneously. The best treatment is to ignore the hair pulling and concentrate on why the person is anxious, nervous or frustrated.

Another less common form of hair loss is called telogen effluvium. Following a high fever, crash diet, flu or emotional stress, hairs that were in their growth phase suddenly are converted into the resting phase. Two to four months later, when the person is otherwise fine and the stress is forgotten, these hairs begin to shed and do so for about six weeks. The hair loss is not total or in patches — the hair appears thin throughout the scalp. Unless the initial cause is repeated, all the hairs normally return (telogen effluvium explains why many mothers lose so much hair weeks after childbirth). Most who go to the physician for this condition are worried that they have cancer or another bad disease.

Remember, hair loss is not caused from vitamin deficiencies (at least in the U.S.), poor scalp circulation, headbands, hats or helmets. When people lose their hair, they can probably make the diagnosis themselves. If they have any doubts, they should consult with their physician.