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Alopecia (Hair Loss)



Wendy S. Levinbook

, MD, Hartford Dermatology Associates

Reviewed/Revised Oct 2022 | Modified Nov 2023
Topic Resources

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.

  • 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

Injury to the hair follicles has many causes including

Less common causes include primary hair shaft abnormalities (that is, the abnormality originates in the hair shaft), lichen planopilaris (lichen planus of the scalp) and frontal fibrosing alopecia, , and rare skin conditions.

Did You Know...

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

Androgenetic alopecia

This form of alopecia increases with age and affects over 70% of men (male-pattern hair loss) and 57% of 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 Losing Hair ). Androgenetic alopecia is more common among White people than among 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 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.

Losing Hair

Alopecia areata

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 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).

Autoimmune Disorders

Central centrifugal cicatricial alopecia

Central centrifugal cicatricial alopecia is the most common cause of scarring alopecia in Black women. The combination of damage to the scalp, possibly resulting from hot combs, chemical relaxers, or hair weaves, and a genetic predisposition to follicular damage due to abnormal hair follicles leads 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 Systemic Lupus Erythematosus (SLE) (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 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 Acne , 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 Hairiness ). The most common cause of androgen excess in women is polycystic ovary syndrome Polycystic Ovary Syndrome (PCOS) Polycystic ovary syndrome is characterized by irregular or no menstrual periods and often obesity or symptoms caused by high levels of male hormones (androgens), such as excess body hair and... read more Polycystic Ovary Syndrome (PCOS) (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. Virilization may also 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 Birth 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... read more Congenital adrenal hyperplasia ).


Male-pattern or female-pattern baldness can occur when anabolic steroids are used. Chemotherapy drugs typically cause disruption of the growing phase that causes loss of anagen hairs (anagen effluvium). Other prescription drugs (for example, blood thinners and drugs used to treat high blood pressure, acne, thyroid disorders, or seizures) typically cause hair loss by inducing a telogen effluvium.

Nutritional disorders

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 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 Hair-Pulling Disorder (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 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 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 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 Scalp Ringworm (Tinea Capitis) 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:

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). They ask 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 . Doctors review the person's current and recent drug use and family history of 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 Losing Hair ) and look at hairs under a microscope for abnormalities of the 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 may be asked whether they use prescription or illegal drugs and may 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 while combing first thing in the morning or during shampooing 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 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:

Traction alopecia is treated by eliminating physical traction or stress to the scalp.

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 Hair-Pulling Disorder (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, topical minoxidil is effective for male- and female-pattern hair loss. 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. Minoxidil can also be taken by mouth.

Finasteride works by blocking the effects of male hormones on the hair follicles and is taken by mouth daily. Finasteride is occasionally used in women who are postmenopausal. It should never be used by pregnant women because it causes birth defects in animals, so whether it is safe in pregnancy is unknown. 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, 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 , and rarely to symptoms of depression. Finasteride can also decrease prostate-specific antigen (PSA) levels. Men should discuss how finasteride can affect prostate cancer screening Screening Prostate cancer begins in 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 urinate frequently... read more 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.

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.

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 therapy 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 Plasma (the liquid part of blood) and platelets Platelets The main components of blood include Plasma Red blood cells White blood cells Platelets read more 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

  • 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

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

Drugs Mentioned In This Article

Generic Name Select Brand Names
A Mulsin, Aquasol A, Dofsol-A
Prozac, Prozac Weekly, Sarafem, Selfemra
Luvox, Luvox CR
Brisdelle, Paxil, Paxil CR, Pexeva
Zoloft, Zoloft Concentrate, Zoloft Solution
Loniten, Rogaine
Propecia, Proscar
Aldactone, CAROSPIR
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