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Alopecia (Hair Loss)



Wendy S. Levinbook

, MD, Hartford Dermatology Associates

Last full review/revision Nov 2020| Content last modified Nov 2020

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 reasons, but it can also be a sign of a bodywide (systemic) disorder.

Hair grows in cycles (see also Overview of Hair Growth). 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

  • Male-pattern and female-pattern baldness (androgenetic alopecia)

Other common causes of hair loss are

  • Alopecia areata
  • Certain systemic disorders, such as illnesses that cause high fever, systemic lupus erythematosus (lupus) or cutaneous lupus erythematosus, hormonal disorders, and nutritional deficiencies
  • Drugs, particularly chemotherapy
  • Fungal infections, such as ringworm of the scalp (tinea capitis)
  • Physical stresses, such as a high fever, surgery, a major illness, sudden weight loss, or pregnancy (which can lead to a telogen effluvium)
  • Psychologic stresses
  • Injury (trauma)

Injury to the hair follicles has many causes including

  • Trichotillomania (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 (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...

  • About 50 to 100 scalp hairs normally fall out each day.

Androgenetic alopecia

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). 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.

Losing Hair

In men, hair is usually first lost at the forehead 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.

Losing Hair

Alopecia areata

In alopecia areata, 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 (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.

Hormone imbalance

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, and hair growth in locations more typical of male hair growth, such as the face and trunk (hirsutism). The most common cause of androgen excess in women is polycystic ovary syndrome (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 to enhance athletic performance or in those with a genetic disorder that affects the adrenal glands (congenital adrenal hyperplasia).


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

Nutritional disorders are a less common cause of hair loss. Symptoms vary according to the specific nutritional disorder:

  • Excess vitamin A: Rash, scaly chapped lips, painful swelling of the limbs, sluggishness, loss of appetite, and weight loss
  • Iron deficiency: Anemia, easy exhaustion, and a decreased ability to exercise
  • Zinc deficiency: Rash, diarrhea, frequent infections, loss of appetite, and poor wound healing

Physical stresses

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.

Psychologic stresses

These stresses can lead to the habitual twisting, teasing, or pulling out of normal hair (trichotillomania). 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 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 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.

Traction alopecia

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.

Warning signs

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), 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. 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) 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.

Some Causes and Features of Hair Loss


Common Features*


Hair loss over the entire scalp

Male-pattern hair loss (androgenetic alopecia)

Often a family history

Sometimes a history of using anabolic steroids

A doctor's examination

Female-pattern hair loss (androgenetic alopecia)

Often a family history

Sometimes occurring during menopause

Sometimes in women with masculine characteristics (virilization), a history of using anabolic steroids such as dihydrotestosterone, or a tumor that produces male hormones

Sometimes PCOS

A doctor's examination

Sometimes measurement of hormones: testosterone, DHEAS, FSH, and LH

Drugs and toxins

A history of using a specific drug such as certain chemotherapy drugs, anticoagulants, retinoids, oral contraceptives, ACE inhibitors, beta-blockers, lithium, antithyroid drugs, anticonvulsants, or high doses of vitamin A or of being exposed to metals such as thallium and arsenic

A doctor's examination

Sometimes blood tests to check for exposure to toxins or heavy metals

Stress (psychologic or physical) causing telogen effluvium

Severe psychologic stress

Recent weight loss, surgery, severe illness with a fever, or delivery of a baby

A doctor's examination

Sometimes blood tests to check for anemia and iron deficiency and to evaluate thyroid function

Thyroid disorders

With hyperthyroidism (an overactive thyroid gland), difficulty tolerating heat, sweating, weight loss, bulging eyes, shakiness (tremor), restlessness, and an enlarged thyroid gland (goiter)

With hypothyroidism (an underactive thyroid gland), difficulty tolerating cold, weight gain, coarse and thick skin, and sluggishness

A doctor's examination

Blood tests that evaluate thyroid function

Nutritional disorders, such as vitamin A excess or a deficiency of iron or zinc

Symptoms of the specific nutritional disorder

A doctor's examination

Sometimes blood tests to check for nutritional disorders

Alopecia areata

Typically patchy hair loss, but sometimes loss of all scalp hair (alopecia totalis)

Sometimes loss of all body and scalp hair (alopecia universalis)

A doctor’s examination†

Hair loss only in a specific area of the scalp

Alopecia areata

Round patches of hair loss with short broken hairs (resembling exclamation points) around the edges of the patches

Sometimes a burning sensation or itching

Sometimes loss of hair from the side and back edges of the scalp (ophiasis) or central hair loss, with sparing of the hairs at the margin of the scalp (sisaipho)

A doctor’s examination†

Cutaneous lupus erythematosus

Scattered patches of hair loss

Sometimes a rash on the scalp that tends to be red, raised, and scaly

Sometimes areas of scarring

Sometimes itching

A doctor's examination

Blood tests to check for lupus

Biopsy of the scalp

Central centrifugal cicatricial alopecia

Slowly progressive hair loss and scarring on the top and back of the scalp

Possibly caused by the use of hot combs, chemical relaxers, or hair weaves in people who have a genetic predisposition to develop this disorder

A doctor's examination

Biopsy of the scalp

Lichen planopilaris (lichen planus of the scalp) and frontal fibrosing alopecia

Related disorders that cause scattered patches of hair loss and scarring

Called frontal fibrosing alopecia when scarring hair loss occurs predominantly along the front of the hairline and the eyebrows

A doctor's examination

Biopsy of the scalp

Burns, injuries, or radiation (for example, from radiation therapy)

A history of burns, radiation therapy, or injury

Often scarring

A doctor's examination

Tinea capitis (ringworm of the scalp)

Bald areas sometimes with small black dots (due to hair that has broken off at the scalp surface) or hairs broken just above the scalp surface

Round, scaly areas of skin, which can be red or inflamed

A doctor's examination†

Examination of plucked hairs under a microscope and/or culture of plucked hairs

Sometimes a Wood light examination

Traction alopecia

Braids, rollers, or ponytails that are left in too long or pulled too tight

A doctor's examination†

Trichotillomania (compulsive hair pulling)

Typically an asymmetric, bizarre, irregular hair loss pattern

Sometimes obsessive-compulsive behavior

Affects women 4 times more often than men

A doctor's examination†

* Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present.

† Rarely, biopsy of the scalp is done.

ACE = angiotensin-converting enzyme; DHEAS = dehydroepiandrosterone sulfate; FSH = follicle-stimulating hormone; LH = luteinizing hormone; PCOS = polycystic ovary syndrome.


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 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 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 and see also Zinc Deficiency).
  • Vitamin A intake can be decreased in people who have alopecia caused by vitamin A excess.
  • Alopecia areatacan 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 is treated with antifungal drugs taken by mouth.

Trichotillomania 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
  • Hair transplantation
  • Wigs


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. Finasteride can also decrease prostate-specific antigen (PSA) levels. Men should discuss how finasteride can affect prostate cancer screening 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) or spironolactone, may be useful in some women.

Hair transplantation

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.

Other options

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 (the liquid part of blood) and platelets (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

Drugs Mentioned In This Article

Generic Name Select Brand Names
spironolactone ALDACTONE
escitalopram LEXAPRO
clomipramine ANAFRANIL
fluvoxamine LUVOX
sertraline ZOLOFT
citalopram CELEXA
paroxetine PAXIL
fluoxetine PROZAC, SARAFEM
minoxidil ROGAINE
lithium LITHOBID

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