Causes Hair Loss?
The reasons for hair loss are many.
When hair loss begins suddenly, the cause may be due to illness,
diet, medication, or childbirth. If hair loss is gradual and becomes
more noticeable with each passing year, a person may have hereditary
hair loss. Certain hair care practices also can cause noticeable
The following summarizes some of the
many causes for hair loss:
Hereditary thinning or baldness.
Also called androgenetic alopecia, this is the most
common cause of hair loss. When men have hereditary hair loss, a
receding hairline is common as well as hair loss on top of the
scalp. Women, on the other hand, tend to keep their hairline and
have visible thinning over the front and top of the scalp. Very
rarely, a man will experience the female pattern of hereditary
hair loss and a woman will show signs of male-pattern hair loss.
The reasons for this are unknown. About 80 million men and women
in the United States have hair loss due to hereditary thinning
Alopecia areata. This
autoimmune disease causes hair loss on the scalp and elsewhere
on the body. It develops in people of all ages and causes hair
to fall out in patches.
Cicatricial (scarring) alopecia.
Developing in otherwise healthy men and women, cicatricial
alopecia is a rare condition that destroys a person’s hair
follicles. Scar tissue forms where the follicles once were and
re-growth is not possible. Treatment attempts to stop the
inflammation that destroys the hair follicles.
Underlying medical condition.
A warning sign for about 30 diseases, hair loss often can be
stopped or reversed with treatment for the underlying disease.
Two common underlying medical conditions that can cause hair
loss are thyroid disease and anemia caused by an iron
Some cancer treatments.
Radiation therapy and some chemotherapeutic medications cause
hair loss. While hair loss is usually temporary, it can be the
most traumatic part of therapy.
Ringworm of the scalp.
Without effective treatment, this contagious fungal infection,
which is most common in children, can cause balding and scaling
on the scalp.
impulse control disorder causes people to repeatedly pull out
their own hair. Aside from a constant urge to pull out the hair
on the scalp, sufferers often say they feel compelled to pull
out their eyelashes, nose hairs, eyebrows, and other hairs on
Stress and Hormones
Physical stress. Significant
hair loss can occur after a major surgery, high fever, severe
infection, or even the flu.
Hormones fluctuate. A
dramatic change in hormone levels can cause hair loss –
especially in women. Hair loss is common during menopause and
after childbirth due to falling estrogen levels. When hair loss
is caused by falling estrogen levels, the loss is usually
temporary and hair re-growth occurs with time. If a woman is 40
years of age or older, she should not expect to see the hair of
her youth with re-growth.
Weight loss. Even people
losing weight in a physician-monitored program can experience
some hair loss 3 to 6 months after losing more than 15 pounds.
This hair loss is common, and hair growth does return to normal.
Vitamin A excess. Getting
too much vitamin A through vitamin supplements or medications
can lead to hair loss. Once the body no longer has an excess of
vitamin A, normal hair growth resumes.
Protein intake too low. When
the body does not get enough protein, it conserves the protein
it does get by shifting hair growth into the resting phase.
Within 2 to 3 months, the person usually sees visible hair loss.
This can be reversed and prevented by eating enough protein.
Meats, eggs, and fish are good sources. Vegetarians can increase
their protein intake by adding nuts, seeds, and beans to their
Iron intake too low.
Consuming too little iron can lead to hair loss. Good vegetarian
sources of iron are iron-fortified cereals, soybeans, pumpkin
seeds, white beans, lentils, and spinach. Clams, oysters, and
organ meats top the list of good animal sources of iron.
Eating disorder. An eating
disorder such as anorexia or bulimia can lead to hair loss.
Prescription medications that can cause hair loss include:
High-dose vitamin A
Medicines that treat arthritis,
depression, gout, heart problems, and high blood pressure
Birth control pills. Some women
taking or discontinuing birth control pills experience hair
loss. This usually occurs in women with an inherited tendency
toward hair thinning.
Hair Care Practices
Hair cosmetics. Frequent
bleaching or permanents can cause the hair to break. Regular or
improper use of dyes, gels, relaxers, and sprays also can cause
hair breakage. Dermatologists recommend limiting use of these
hair cosmetics to reduce hair breakage.
Blow dryers, flat irons, and
similar devices. Frequent use of a blow dryer tends to
damage hair. The high heat from a blow dryer can boil the water
in the hair shaft leaving the hair brittle and prone to
breakage. Allowing the hair to air dry and styling it only when
dry will lessen this risk. Dermatologists also recommend
limiting the use of flat irons, which straighten hair by using
high heat, and other devices such as curling irons.
Hairpins, clips, and rubber
bands. When used to hold hair tightly, hairpins, clips, and
rubber bands can break hair. When selecting hairpins,
dermatologists recommend choosing one with a smooth, ball-tipped
surface. Hair clips should have spongy rubber padding where they
make contact with the hair. To minimize hair breakage, use
loosely fitting clips and wear them in different areas of the
scalp so that hair breakage is not localized in a specific area.
Rather than using rubber bands for ponytails, try fabric
scrunchies, which loosely hold the hair.
Certain hairstyles. Years of
wearing hair in a style that pulls on the hair such as a
ponytail, cornrows, or braids can cause a type of hair loss
known as traction alopecia.
Too much or vigorous grooming.
Too much shampooing, combing, or brushing (100 strokes or more a
day) or doing any of these too vigorously can cause hair
breakage. When hair breakage occurs, the hair appears shaggy or
too thin. Dermatologists also caution against vigorously rubbing
wet hair with a towel to dry it or combing wet hair. These also
can cause hair breakage because wet hair is more elastic and
more vulnerable to breakage than dry hair.
Dermatologists Can Get to the Root
of Hair Loss
With so many causes, it can take a bit of detective work to uncover
the reason for hair loss. Sometimes, more than one cause is
responsible. And as we age, one cause may follow another.
To diagnose the cause of hair loss, a
dermatologist usually begins by obtaining a detailed medical
history. The patient is asked about medications taken, allergies,
family history, and diet. Women are asked about their menstruation,
pregnancy, and menopause. The dermatologist also performs a detailed
inspection of the hair and scalp and looks at the way the hair is
distributed over the rest of the body. While examining the hair and
scalp, the dermatologist will examine the pattern of hair loss and
look for signs of illness, including any indication of a scalp
infection. Sometimes a hair pull, blood test, or scalp biopsy is
necessary to make the diagnosis.
Once the cause (or causes) is known,
treatment or preventive measures can begin. It is important to
realize that when it comes to hair loss, there is no quick fix. But
dermatologists do have the knowledge and resources to halt hair loss
and generate new growth for many patients.
Cosmetic Procedures: Hair Restoration
Age-related Skin Concerns: Hair Loss
American Academy of Dermatology, “Alopecia Areata.” Available at:
Last accessed August 4, 2008.
American Academy of Dermatology. "Dermatologists Warn Ceramic Flat
Irons Could Damage Hair and Lead to Hair Breakage." News release
issued July 30, 2008.
Last accessed August 5, 2008.
American Academy of Dermatology. “Hair Loss Fact Sheet.” Available
Last accessed August 4, 2008.
Bergfeld, WF. “Female Hair Loss.” Presented during a symposium (SYM
308) at the Summer Academy Meeting of the American Academy of
Dermatology, August 2008; Chicago.
All content solely
developed by the American Academy of Dermatology
About 80 million American
men and women have hereditary hair loss, and at least
half of the women in the United States will experience
some form of hair loss by the time they reach 50 years