Hair grows in cycles (see also Overview of Hair Growth Overview of Hair Growth Hair originates in the hair follicles. These follicles are located in the dermis, the skin layer just below the surface layer and above the subcutaneous fat. Hair follicles are present everywhere... read more ). Each cycle consists of
A long growing phase (anagen) lasting 2 to 6 years
A brief transitional phase (catagen) lasting 3 weeks
A short resting phase (telogen) lasting 2 to 3 months
At the end of the resting phase, the hair falls out (exogen), and the cycle begins again as a new hair starts growing in the follicle. Normally, about 50 to 100 scalp hairs reach the end of resting phase each day and fall out.
Disorders of the growth cycle that lead to hair loss include
Anagen effluvium: Disruption of the growing phase that causes loss of anagen hairs
Telogen effluvium: Many more than 100 hairs a day go into resting phase and then fall out
Doctors sometimes classify hair loss as focal (confined to one part of the scalp) or diffuse (widespread). Hair loss may also be classified by whether or not scarring exists.
Causes of Alopecia
The most common cause of hair loss is
Other common causes of hair loss are
Certain systemic disorders, such as illnesses that cause high fever, systemic lupus erythematosus (lupus) Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more or cutaneous lupus erythematosus Cutaneous lupus erythematosus Hair loss, also called alopecia, can occur on any part of the body. Hair loss that occurs on the scalp is generally called baldness. Hair loss is often of great concern to people for cosmetic... read more , hormonal disorders, and nutritional deficiencies
Drugs, particularly chemotherapy
Fungal infections, such as ringworm of the scalp ( tinea capitis Scalp Ringworm (Tinea Capitis) Scalp ringworm is a dermatophyte (fungal) infection of the scalp. Symptoms of tinea capitis include a dry patch of scale, a patch of hair loss, or both on the scalp. Doctors base the diagnosis... read more )
Physical stresses, such as a high fever, surgery, a major illness, sudden weight loss, or pregnancy (which can lead to a telogen effluvium)
Injury to the hair follicles has many causes including
Trichotillomania Hair-Pulling Disorder (Trichotillomania) In hair-pulling disorder, people repeatedly pull their hair out, resulting in hair loss. People with hair-pulling disorder may feel tense or anxious just before they pull their hair out, and... read more (habitual pulling out of normal hair related to psychologic stresses)
Traction alopecia (hair loss caused by continuous traction such as from braids, rollers, or ponytails)
Central centrifugal cicatricial alopecia Central centrifugal cicatricial alopecia Hair loss, also called alopecia, can occur on any part of the body. Hair loss that occurs on the scalp is generally called baldness. Hair loss is often of great concern to people for cosmetic... read more (hair loss with scarring of the scalp)
Burns and radiation
Pressure-induced hair loss (for example, after an operation where prolonged pressure on the scalp caused damage to hair follicles)
Less common causes include primary hair shaft abnormalities (that is, the abnormality originates in the hair shaft), sarcoidosis, heavy metal poisoning, radiation therapy, and rare skin conditions.
Did You Know...
This form of alopecia may eventually affect over 70% of men (male-pattern hair loss) and 50% of all women (female-pattern hair loss) over the age of 80. The hormone dihydrotestosterone plays a major role, along with heredity. The hair loss can begin at any age during or after puberty, even during adolescence (see figure Losing Hair Losing Hair ). Androgenetic alopecia is more common among white people than among Chinese, Asian, and black people.
In men, hair loss usually begins at the temples or on the top of the head toward the back. Some men lose only some hair and have only a receding hairline or a small bald spot in the back. Other men, especially when hair loss begins at a young age, lose all of the hair on the top of the head but retain hair on the sides and back of the scalp. This pattern is called male-pattern hair loss.
In women, hair loss occurs on the top of the head and is usually a thinning of the hair rather than a complete loss of hair. The hairline typically stays intact. This pattern is called female-pattern hair loss.
In men, hair is usually first lost at the temples or on the top of the head toward the back. This pattern is called male-pattern hair loss.
In women, hair is usually first lost on the top of the head. Typically, the hair thins rather than is completely lost, and the hairline stays intact. This pattern is called female-pattern hair loss.
In alopecia areata Alopecia Areata Alopecia areata is sudden loss of patches of hair when there is no obvious cause such as a skin or general internal disorder. (See also Overview of Hair Growth and Hair Loss [Alopecia].) Alopecia... read more , typically round, irregular patches of hair are suddenly lost. More extensive loss of scalp and body hair can also occur. This disorder is believed to be caused by a malfunction of the body's immune system that causes the body to attack its own tissues (called an autoimmune reaction).
Central centrifugal cicatricial alopecia
Central centrifugal cicatricial alopecia is the most common cause of scarring alopecia in black women. Damage to the scalp, possibly resulting from hot combs, chemical relaxers, or hair weaves, in association with a genetic predisposition to follicular damage due to abnormal hair follicles lead to progressive hair loss and scarring on the top and back of the scalp.
Cutaneous lupus erythematosus
In cutaneous lupus erythematosus, areas of hair may be lost. Hair loss may be permanent if the hair follicle is completely destroyed. Cutaneous lupus erythematosus can affect people who have or do not have systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more (SLE, or simply lupus), a disorder in which antibodies or cells produced by the body attack the body's own tissues (called an autoimmune disorder). Systemic lupus erythematosus affects various organs throughout the body and can cause widespread nonscarring hair loss. In cutaneous lupus erythematosus, hair tends to be lost in patches and scarring or permanent hair loss can occur.
If women have excessive amounts of male hormones or are more sensitive to the effects of male hormones (for example, genetically), they can develop scalp hair loss, acne Acne Acne is a common skin condition causing pimples and other abnormalities on the face and upper torso. Acne is caused by a buildup of dead skin cells, bacteria, and dried sebum that blocks the... read more , and hair growth in locations more typical of male hair growth, such as the face and trunk ( hirsutism Hairiness In men, the amount of body hair varies greatly (see also Overview of Hair Growth), but very few men are concerned enough about excess hair to see a doctor. In women, the amount of hair that... read more ). The most common cause of androgen excess in women is polycystic ovary syndrome Polycystic Ovary Syndrome (PCOS) Polycystic ovary syndrome is characterized by slight obesity, irregular or no menstrual periods, and symptoms caused by high levels of male hormones (androgens). It involves disruption of the... read more (PCOS). Women who have PCOS usually have excess face and body hair, and some have loss of scalp hair (female-pattern baldness). Virilization occurs when androgen levels are high enough to cause not only scalp hair loss but also additional signs and symptoms such as deepening of the voice, decrease in the size of the breasts, increased muscle bulk, irregular menstrual periods, an enlarged clitoris (the smaller female organ that corresponds to the penis), and increased libido. Rarely an ovarian or adrenal tumor can secrete male hormones, causing virilization, or virilization may develop in a female who is taking anabolic steroids Anabolic Steroids Anabolic steroids are synthetic (man-made) versions of testosterone that are used to increase muscle size. Anabolic steroids are hormones that promote muscle growth and increase strength and... read more to enhance athletic performance or in those with a genetic disorder that affects the adrenal glands ( congenital adrenal hyperplasia Congenital adrenal hyperplasia Defects of the genitals can involve the penis, scrotum, or testes (testicles) in boys and the vagina and labia in girls. Sometimes the genitals are ambiguous, that is, not clearly female or... read more ).
Male-pattern or female-pattern baldness can occur when anabolic steroids are used. Chemotherapy drugs typically cause anagen effluvium. Other prescription drugs (for example, drugs used to treat high blood pressure, acne, thyroid disorders, seizures, or blood thinners) typically cause hair loss by inducing a telogen effluvium.
Nutritional disorders are a less common cause of hair loss. Symptoms vary according to the specific nutritional disorder:
Excess vitamin A Vitamin A Excess Vitamin A excess (toxicity) can be sudden (acute), usually due to accidental ingestion by children, or chronic. Consuming too much vitamin A causes hair loss, cracked lips, dry skin, weakened... read more : Rash, scaly chapped lips, painful swelling of the limbs, sluggishness, loss of appetite, and weight loss
Iron deficiency Iron Deficiency Iron deficiency is a common cause of anemia, a condition in which the number of red blood cells is low. Iron deficiency usually results from loss of blood in adults (including bleeding from... read more : Anemia, easy exhaustion, and a decreased ability to exercise
Zinc deficiency Zinc Deficiency Zinc deficiency has many causes, including various disorders, alcohol use disorder, and use of diuretics. People lose their appetite and hair and may feel sluggish and lose their sense of taste... read more : Rash, diarrhea, frequent infections, loss of appetite, and poor wound healing
Stresses such as a high fever, surgery, a major illness, weight loss, or pregnancy can increase the number of hairs that go into the resting phase (causing telogen effluvium). Hair typically falls out a few months after the stress. This type of hair loss tends not to be permanent.
These stresses can lead to the habitual twisting, teasing, or pulling out of normal hair ( trichotillomania Hair-Pulling Disorder (Trichotillomania) In hair-pulling disorder, people repeatedly pull their hair out, resulting in hair loss. People with hair-pulling disorder may feel tense or anxious just before they pull their hair out, and... read more ). The habit is most common among children but may occur in adults. The hair pulling may not be noticed for a long time, confusing doctors and parents, who may mistakenly think that a disorder such as alopecia areata Alopecia Areata Alopecia areata is sudden loss of patches of hair when there is no obvious cause such as a skin or general internal disorder. (See also Overview of Hair Growth and Hair Loss [Alopecia].) Alopecia... read more or a fungal infection is causing the hair loss. Severe, prolonged psychologic stress also can cause hair to fall out on its own (telogen effluvium). This hair loss, however, involves major, chronic stress and not the routine stresses of daily life.
Ringworm of the scalp (tinea capitis)
Scalp ringworm Scalp Ringworm (Tinea Capitis) Scalp ringworm is a dermatophyte (fungal) infection of the scalp. Symptoms of tinea capitis include a dry patch of scale, a patch of hair loss, or both on the scalp. Doctors base the diagnosis... read more is a fungal infection that is a common cause of patchy hair loss in children. The infection begins as a dry, scaly patch that gradually enlarges. Hairs may eventually break off, usually flush with the surface of the scalp, looking like black dots. Sometimes the hair breaks off above the surface of the scalp, leaving short stubs. Hair loss may be permanent, especially if the infection is left untreated.
This disorder is hair loss caused by tight braids, rollers, or ponytails that pull constantly on hair. Hair loss most often occurs at the hairline of the forehead and temples.
Evaluation of Alopecia
The following information can help people decide whether a doctor's evaluation is needed and help them know what to expect during the evaluation.
The following are of particular concern:
Signs of a bodywide disorder
In women, development of masculine characteristics (virilization), such as a deepened voice, hair in locations more typical of male hair growth ( hirsutism Hairiness In men, the amount of body hair varies greatly (see also Overview of Hair Growth), but very few men are concerned enough about excess hair to see a doctor. In women, the amount of hair that... read more ), irregular menstrual periods, acne, breast atrophy, increased muscle bulk, enlarged clitoris, and increased libido (sex drive)
When to see the doctor
People who have hair loss and signs of a bodywide disorder should see a doctor promptly. Women who have developed masculine characteristics should call their doctor to discuss how soon they should be seen. Other people should see a doctor when possible, but an appointment is not urgent unless other symptoms develop.
What the doctor does
Doctors first ask questions about the person's symptoms and medical history and then do a physical examination. What doctors find during the history and physical examination often suggests a cause of the hair loss and the tests that may need to be done.
Doctors ask about the hair loss:
Whether hair loss began gradually or suddenly
How long it has been present
Whether hair loss is increasing
Whether hair is being lost over the entire head or in one specific area
They note other symptoms such as itching and scaling. They ask about hair care, including whether braids, rollers, and hair dryers are used and whether the hair is routinely pulled or twisted.
Doctors ask whether the person has been recently exposed to drugs, toxins, or radiation or has experienced significant stress (such as that resulting from surgery, chronic illness, fever, or psychologic stress). The person is asked about other characteristics that may suggest a cause, including dramatic weight loss, dietary practices (including various restrictive diets), and obsessive-compulsive behavior Obsessive-Compulsive Disorder (OCD) Obsessive-compulsive disorder is characterized by obsessions, compulsions, or both. Obsessions are recurring, persistent, unwanted, anxiety-provoking, intrusive ideas, images, or urges. Compulsions... read more . Current and recent drug use is reviewed. The person is asked whether any family member has had hair loss.
During the physical examination, doctors focus on the scalp, noting the distribution of hair loss, the presence and characteristics of any skin abnormalities, and the presence of any scarring. They measure the width of the central part of the scalp at several points ( see Figure: Losing Hair Losing Hair ) and check for abnormalities of hair shafts.
Doctors evaluate hair loss elsewhere on the body (such as the eyebrows, eyelashes, arms, and legs). They look for rashes that may be associated with certain types of alopecia and for signs of virilization in women such as a deepened voice, hirsutism, an enlarged clitoris, and acne. They also examine the thyroid gland.
Testing is usually unnecessary if a cause is identified based on the doctor's examination. For example, male-pattern or female-pattern hair loss generally requires no testing. However, if hair loss occurs in a young man with no family history of hair loss, the doctor may question him about use of anabolic steroids Anabolic Steroids Anabolic steroids are synthetic (man-made) versions of testosterone that are used to increase muscle size. Anabolic steroids are hormones that promote muscle growth and increase strength and... read more and other drugs. Women who have significant hair loss and who have developed masculine characteristics are asked whether they use prescription or illegal drugs and undergo blood tests to measure levels of the hormones testosterone and dehydroepiandrosterone sulfate (DHEAS). If the doctor's examination detects signs of other hormonal abnormalities or other serious illness, blood tests to identify those disorders may be needed (for example, tests to measure luteinizing hormone [LH] and follicle-stimulating hormone [FSH] may be done to diagnose polycystic ovary syndrome [PCOS]).
The pull test helps doctors evaluate hair loss. Doctors gently pull on a bunch of hairs (about 40) on at least 3 different areas of the scalp. Doctors then count the number of hairs that come out with each pull and examine them under a microscope to determine their phase of growth. If more than 4 to 6 hairs in the telogen phase come out with each pull, the pull test is positive, and the person most likely has telogen effluvium.
During the pluck test, doctors abruptly pull out about 50 individual hairs (“by the roots”). Doctors examine the roots and shafts of the plucked hairs under a microscope to assess the hair shaft and determine the phase of growth. These results help doctors tell whether the person has a telogen effluvium, a primary hair shaft abnormality, or some other problem.
Daily hair counts can be done to quantify hair loss when the pull test is negative and it is not clear whether hair loss is actually excessive. Hairs lost in the first morning combing or during washing are collected in clear plastic bags daily for 14 days. The number of hairs in each bag is then recorded. Loss of more than 100 hairs a day is abnormal except after shampooing, when up to 250 hairs may be lost. Hairs may be brought in by the person for examination under a microscope.
A biopsy Biopsy Doctors can identify many skin disorders simply by looking at the skin. A full skin examination includes examination of the scalp, nails, and mucous membranes. Sometimes the doctor uses a hand-held... read more of the scalp skin is done if the diagnosis is not clear after a doctor's examination and other tests. A biopsy helps determine whether hair follicles are normal and can help differentiate alopecia that causes scarring (by destroying the hair follicle) from alopecia that does not. If the hair follicles are abnormal, the biopsy may indicate possible causes.
Treatment of Alopecia
Treatment of specific causes
Sometimes hair replacement methods
Specific causes of hair loss are treated when possible:
Drugs that are causing hair loss are switched or stopped.
Hormonal disorders can be treated with drugs or surgery, depending on the cause.
Iron or zinc supplements can be given if these minerals are deficient ( see Iron Deficiency Iron Deficiency Iron deficiency is a common cause of anemia, a condition in which the number of red blood cells is low. Iron deficiency usually results from loss of blood in adults (including bleeding from... read more and see also Zinc Deficiency Zinc Deficiency Zinc deficiency has many causes, including various disorders, alcohol use disorder, and use of diuretics. People lose their appetite and hair and may feel sluggish and lose their sense of taste... read more ).
Vitamin A intake can be decreased in people who have alopecia caused by vitamin A excess.
Alopecia areata Treatment Alopecia areata is sudden loss of patches of hair when there is no obvious cause such as a skin or general internal disorder. (See also Overview of Hair Growth and Hair Loss [Alopecia].) Alopecia... read more can usually be treated with corticosteroids that are injected into the skin, applied to the scalp (topical), or taken by mouth (oral). Other topical and oral drugs may be given.
Cutaneous lupus erythematosus, lichen planopilaris, and frontal fibrosing alopecia can usually be treated with corticosteroids that are injected into the skin or applied topically or with other topical or oral drugs.
Traction alopecia is treated by eliminating physical traction or stress to the scalp.
Scalp ringworm Scalp Ringworm (Tinea Capitis) Scalp ringworm is a dermatophyte (fungal) infection of the scalp. Symptoms of tinea capitis include a dry patch of scale, a patch of hair loss, or both on the scalp. Doctors base the diagnosis... read more is treated with antifungal drugs taken by mouth.
Trichotillomania Hair-Pulling Disorder (Trichotillomania) In hair-pulling disorder, people repeatedly pull their hair out, resulting in hair loss. People with hair-pulling disorder may feel tense or anxious just before they pull their hair out, and... read more is difficult to treat, but behavioral modification, clomipramine, or a selective serotonin reuptake inhibitor (such as fluoxetine, fluvoxamine, paroxetine, sertraline, escitalopram, or citalopram) may be useful.
Hair loss due to physical stresses such as recent weight loss, surgery, a severe illness with a high fever, or delivery of a baby (telogen effluvium) is not typically treated because it tends to resolve on its own. Applying minoxidil to the scalp may be helpful for some people.
Hair replacement methods can be tried if hair does not regrow on its own, including
Drugs to prevent further hair loss or grow new hair
Male-pattern and female-pattern hair loss can sometimes be treated effectively with drugs.
Minoxidil may prevent further hair loss and increase hair growth when applied directly to the scalp twice a day. Hair regrowth can take 8 to 12 months and is noticeable in only about 30 to 40% of people. The most common side effects are skin irritation, such as itching and rash. An increase in hair on the face can also occur.
Finasteride works by blocking the effects of male hormones on the hair follicles and is taken by mouth daily. Finasteride is sometimes used for women but should never be used in pregnant women. In men, its effectiveness at stopping hair loss and stimulating hair growth is usually evident within 6 to 8 months of treatment and increases over time but can vary from person to person. Finasteride can decrease libido, increase breast size, and contribute to erectile dysfunction Erectile Dysfunction (ED) Erectile dysfunction (ED) is the inability to attain or sustain an erection satisfactory for sexual intercourse. (See also Overview of Sexual Dysfunction in Men.) Every man occasionally has... read more . Finasteride can also decrease prostate-specific antigen (PSA) levels. Men should discuss how finasteride can affect prostate cancer screening Diagnosis Prostate cancer begins in a small area of the prostate gland, an organ found only in males. The risk of prostate cancer increases as men age. Symptoms, such as difficulty urinating, a need to... read more with their doctor before they begin treatment.
The most important effect of minoxidil or finasteride may be to prevent further hair loss. The effects last only as long as the drugs are taken.
Hormonal modulators, such as birth control pills ( oral contraceptives Oral Contraceptives Contraceptive hormones can be Taken by mouth (oral contraceptives) Inserted into the vagina (vaginal rings) Applied to the skin (patch) Implanted under the skin read more ) or spironolactone, may be useful in some women.
Transplantation is a more permanent solution. In this procedure, hair follicles are removed from one part of the scalp and transplanted to the bald area. In this technique, only one or two hairs are transplanted at a time. Although this technique is more time-consuming, it does not require removal of large plugs of skin and allows the implants to be oriented in the same direction as the natural hair.
Another surgical option involves removing some bald parts of the scalp skin and stretching the parts that have hair over a wider area.
Wigs often offer the best treatment for temporary hair loss (for example, that caused by chemotherapy). People undergoing chemotherapy should consult a wig maker even before therapy begins so that an appropriate wig can be ready when needed. When hair regrows, it may be different in color and texture from the original hair.
Laser light therapy is an alternate or additional treatment for male- and female-pattern hair loss (androgenetic alopecia) that has been shown to promote hair growth. Over-the-counter devices are available, or doctors can do laser light therapies in the office.
A newer treatment that may promote growth of the hair follicles involves the use of a person's own plasma Plasma The main components of blood include Plasma Red blood cells White blood cells Platelets read more (the liquid part of blood) and platelets Platelets The main components of blood include Plasma Red blood cells White blood cells Platelets read more (small blood cells that help blood clot). Platelets are thought to contain substances that trigger hair growth. In this treatment, called platelet-rich plasma therapy or PRP therapy, blood is taken from a person and processed to remove the platelet-rich plasma. The platelet-rich plasma is then injected into bald patches and may stimulate the growth of new hair.
Some people conceal thinning hair by using camouflage powders, hair loss concealers (products that contain fibers that bind to existing hair), and a form of tattooing called scalp micropigmentation.
Key Points about Alopecia
Male-pattern and female-pattern hair loss is the most common type of hair loss.
Doctors look for an underlying disorder in women with signs of virilization.
Microscopic hair examination or scalp biopsy may be required to determine the reason for the hair loss.
Doctors treat the specific cause of hair loss when possible; otherwise, treatments for male-pattern and female-pattern hair loss include drugs, hair replacement, laser light therapy, and injections of platelet-rich plasma.
More Information about Alopecia
The following are some English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
National Alopecia Areata Foundation: Information about many aspects of alopecia, including links to support groups, community resources, and treatment options
The TLC Foundation for Body-Focused Repetitive Behaviors: Trichotillomania: Information about support groups, treatment options, education, and recovery for people who have trichotillomania