AgingSkinNet Article
What 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 hair loss.

The following summarizes some of the many causes for hair loss:

Hair Disorders

• 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 or baldness.
   

• 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.

Disease

• 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 deficiency.
   

• 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.
   

• Trichotillomania. This 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 their bodies.

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.

Diet

• 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 diet.
   

• 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.

Medication
Prescription medications that can cause hair loss include:

• Blood thinners

• 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.

Related Links
Cosmetic Procedures: Hair Restoration
Age-related Skin Concerns: Hair Loss

References:
American Academy of Dermatology, “Alopecia Areata.” Available at: www.aad.org/public/publications/pamphlets/common_alopecia.html. 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 at: www.aad.org/media/background/factsheets/fact_hair_loss.html.  Last accessed August 4, 2008.

American Academy of Dermatology. "The Key to Beautiful Locks Starts with the Basics." News release issued July 30, 2004. 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.

Supported by an educational donation provided by The Allergan Foundation.