Merck Manual

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Quick Facts

Hair Loss

(Baldness)

By

The Manual's Editorial Staff

Last full review/revision Apr 2019
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NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
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Topic Resources

You can lose hair from a single patch on your scalp or all over your scalp. Rarely, you lose all your body hair.

  • It's normal to lose 50 to 100 hairs every day, as new hair grows and replaces old hair

  • Having a baby, losing a lot of weight quickly, taking certain medicines, having a serious illness, and going through other physically or mentally stressful situations can cause hair loss

  • Twisting or pulling out your hair is another cause of hair loss—people may not notice they're doing it

  • It can be bothersome to lose your hair, but hair loss may also be a sign of a serious health problem

  • Sometimes medicine can help regrow your hair, depending on what caused the hair loss

What causes hair loss?

The most common cause of hair loss is male- or female-pattern baldness.

  • Male-pattern baldness starts at the forehead or top of head and spreads toward the back

  • Female-pattern baldness starts at the top of the head, and hair just thins out rather than leaving a bald patch

Male and female pattern baldness runs in families. It can start as early as your 20s and gets more common as you grow older.

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

Other causes of hair loss include:

  • Alopecia areata, an autoimmune disorder in which your body's immune defenses attack your hair follicles by mistake

  • Certain medicine (especially chemotherapy)

  • Scalp ringworm, a fungal infection

  • Certain body-wide disorders, such as lupus

  • Hormone imbalances, such as women who have too many male hormones or take anabolic steroids for bodybuilding

  • Nutrition problems, such as not getting enough iron or zinc

  • Physical stresses, such as a high fever, surgery, a major illness, sudden weight loss, or pregnancy

  • Mental stress, causing you to pull out your hair

  • Injury to your hair follicles, such as from burns or radiation therapy, tight braids or rollers, chemical hair relaxers, or hot combs

When should I see a doctor for hair loss?

See a doctor within a few days if you have hair loss and you:

  • Are feeling sick or unwell

  • Are a woman and notice signs of hormone imbalance, such as a deeper voice, hair growth in unusual places, irregular menstrual periods, and acne

If you have hair loss but no other symptoms, see a doctor when you can.

How do doctors treat hair loss?

If there's a health problem causing your hair loss, doctors treat that problem. They also treat hair loss with:

  • Medicine for male and female pattern baldness, which can take 8 to 12 months to work

  • Hair transplants to move hair follicles from a hairy area of your scalp to your bald area

  • Wigs

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
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