Hair loss refers to the partial or total loss of hair from a part of the body where it normally grows.
Most of the hair on a person's head is growing constantly. Scalp hair grows about half an inch per month, although this growth rate slows as people age. For each individual hair, the growth stage lasts for two to six years. It is followed by a resting stage, lasting two to three months, during which the hair still is attached but no longer grows. After the resting stage, the hair falls out, and a new hair starts to form. Hair loss occurs when people lose more hairs than normal or when new hairs do not grow to replace the lost ones.
Hair is made of keratin (KER-uh-tin), the same protein that makes up nails and the outer layer of skin. The part of a hair that shows is called the hair shaft. Below the skin is the hair root, which is enclosed in the follicle (FOL-i-kul), a tiny, bulb-shaped structure. The root is alive, but the shaft is composed of dead tissue made by the follicle.
Hair color is inherited and is determined by multiple genes. The color comes from two types of pigment in the hair: pheomelanin (fee-o-MELan-in) and eumelanin (u-MEL-an-in). Pheomelanin ranges from yellowish to reddish in color. Eumelanin is either brown or black. The relative amounts of these two pigments determine hair color.
Hair loss refers to the partial or total loss of hair from a part of the body where it normally grows, especially the scalp. Alopecia (AL-o-PEE-sha) is the medical term for baldness, which is the loss of all or a significant part of the scalp hair. Hair for humans is mostly decorative. Losing hair is not a medical problem in itself, although in some cases, it can be a sign of illness. Many people are comfortable being bald. However, others feel that hair loss impacts their self-image, sense of identity and youth, and may make them feel less attractive.
At least 95 percent of scalp hair loss is caused by a combination of age, genetics, and changes in the level of hormones * called androgens (AN-dro-jenz). This type of hair loss is called androgenetic (AN-dro-jeh-NET-ik) alopecia. In men, the condition usually starts with a hairline that keeps moving higher, followed by a thin or bald spot that appears on top of the head. Eventually, all that may be left is a horseshoe-shaped fringe of hair around the sides and back of the head, known as male-pattern baldness. In women, the condition usually leads to thinning of the hair over the whole head, which is especially common after menopause * . It is known as female-pattern baldness.
Alopecia areata (ar-ee-AY-ta) can develop in people of any age, including children. This condition leads to sudden hair loss, often in round patches on the scalp about the size of a coin or larger. In severe cases, the hair may fall out from the whole head, including the eyebrows and beard, or the whole body. Alopecia areata is thought to be caused by a problem with the immune system * Medical conditions and hair loss
Several medical conditions and treatments can cause hair loss in people of all ages and both sexes. Sometimes, people notice a lot of hair falling out within one to three months after having a high fever, a severe infection, or a major operation. Some women also lose a large amount of hair within a few months after giving birth due to changing hormone levels following pregnancy. Changing hormone levels are also why babies lose a great deal of their hair during the first six months of life. In addition, an overactive or underactive thyroid gland * can cause hair loss, as can ringworm (a fungal infection) of the scalp.
People with certain types of cancer often lose their hair during chemotherapy * . Other medications may cause hair loss as well, including blood thinners, birth control pills, and medicines for depression * and high blood pressure. Fortunately, this kind of hair loss usually is temporary. Typically, the hair grows back once the body adjusts, the disease is treated, or the medicine is stopped.
Trichotillomania (trik-o-til-o-MAY-nee-uh) is a psychological * disorder in which people pull out their own hair, leading to noticeable hair loss. The most commonly affected spots are the scalp, eyebrows, and eyelashes. This nervous habit may be a reaction to emotional stress or anxiety. It often begins in childhood, although it occurs in adults, too. The hair grows back once the hair pulling is stopped.
When people do not get enough protein from their diet, the body may try to save protein by shifting hairs from the growing stage to the resting stage. As a result, a large number of hairs may fall out two to three months later, when the resting stage ends. Lack of iron also can lead to hair loss. Eating a healthy diet or taking iron pills can prevent or reverse this problem.
Chemicals such as dyes, bleaches, straighteners, and those applied for permanents can damage the hair if used too often or left on too long. Even shampooing, brushing, and combing can harm the hair if done too roughly. Hairstyles that pull the hair, such as tight ponytails and braids, also put a lot of stress on it. Mistreating the hair in any of these ways can lead to temporary hair loss.
People who experience sudden, fast, or unusual hair loss should see a physician, who can identify the cause. In some cases, doctors may decide that the baldness is simply due to aging. In other cases, doctors may check the scalp and take samples from it to look for signs of disease. In addition, doctors may pluck several hairs from one spot on the head. These hairs then are examined under a microscope to see whether they are in the growing or resting stage. The percentage of hairs in each stage can provide another clue to the cause of the hair loss.
Hair loss due to alopecia areata usually clears up on its own with time. In the meantime, the condition sometimes is treated with corticosteroid * medicines that are rubbed onto the skin, taken by mouth, or injected.
Common baldness due to aging does not need treatment for medical reasons. However, some people seek help because they are concerned about their appearance. There are several treatment options.
Simply getting the right haircut and styling the hair in a flattering way can make a big difference with thinning hair or scattered hair loss. For more widespread hair loss, wigs are an easy solution. Several kinds of partial wigs, known as hair additions, are available as well. They can be attached to the remaining hair or anchored to the scalp with special glues or fasteners.
Two medications are approved in the United States for regrowing lost hair or preventing further hair loss: minoxidil (mih-NOK-suh-dil) and finasteride (fi-NAS-ter-ide). Minoxidil (Rogaine) can be bought without a prescription. It is a liquid that is rubbed onto the scalp. Only about one-fourth of men and one-fifth of women who use regular-strength minoxidil regrow a significant amount of hair, and it may take several months before these results are noticeable. The new hair often is thinner and lighter in color than the original hair. Also, any hair growth that occurs ceases once the treatment is stopped.
Finasteride (Propecia) is a pill sold by prescription. This drug is approved for sale only to men because it has not been shown to work in women, and it can cause birth defects if used by pregnant women. More than four out of five men who use finasteride have slowing of their hair loss, and more than three out of five have some hair regrowth. As with minoxidil, positive effects can take months to see.
Hair transplantation (trans-plan-TAY-shun) surgery is a lasting but expensive and often painful solution to hair loss. When done for cosmetic reasons, it normally is not covered by medical insurance. The operation involves cutting tiny plugs of hair-bearing scalp from parts of the head where hair still grows, and then reattaching the plugs to bald parts of the head. No new hair is added. Existing hair simply is moved from one spot to another. Because hundreds or even thousands of the tiny plugs must be moved to get good results, the procedure usually is done in several surgery sessions that are months apart. Sometimes, a larger flap of skin is moved instead of many tiny plugs.
Scalp reduction surgery is another procedure, which may be combined with hair transplantation. It involves removing a bald area of scalp from the top of the head and then stretching the hair-bearing scalp to cover the area. Hair surgery is performed by dermatologists, cosmetic surgeons, and plastic surgeons.
Hair loss can be upsetting, even when it is temporary. Hairstyles, wigs, hair additions, hats, scarves, and bandannas can help hide hair loss if it makes a person uncomfortable. For many people, hair loss simply does not matter. Others wear their baldness with pride. Many even shave any remaining hair if the hair loss is patchy.
See also Body Image • Cancer: Overview • Dietary Deficiencies • Fungal Infections
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* hormones are chemical substances that are produced by various glands and sent into the bloodstream carrying messages that have certain effects on other parts of the body.
* menopause (MEN-o-pawz) is the end of menstruation.
* immune system (im-YOON SIS-tem) is the system of the body composed of specialized cells and the substances they produce that helps protect the body against disease-causing germs.
* thyroid gland (THYE-roid GLAND) is located in the lower part of the front of the neck. The thyroid produces hormones that regulate the body's metabolism (meh-TABo- liz-um), the processes the body uses to produce energy, grow, and maintain body tissues.
* chemotherapy (KEE-mo-THER-uhpee) is the treatment of cancer with powerful drugs that kill cancer cells.
* depression (dih-PRESH-un) is a mental state characterized by feelings of sadness, despair, and discouragement.
* psychological (SI-ko-LOJ-i-kal) refers to mental processes, including thoughts, feelings, and emotions.
* corticosteroid (KOR-tih-ko-STAREoid) is one of several medications that are prescribed to reduce inflammation and sometimes to suppress the body's immune response.