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Am Fam Physician. 2009;80(4):373-374

See related article on hair loss.

What is normal hair growth and loss?

Hair normally grows in cycles of two to six years. Each hair grows about one centimeter per month during a cycle. About 90 percent of your hair is growing, and about 10 percent is resting. After two to three months, the resting hair falls out and new hair starts to grow in its place. It is normal to lose up to 100 hairs each day. But, some people may have more hair loss than normal. This can be stressful, can lead to depression, and may affect self-confidence.

What should I do if too much of my hair starts to fall out?

Talk to your doctor. Your doctor will ask you questions and examine you. You may also need some blood tests and a scalp biopsy (taking a small sample of skin to examine under a microscope).

What causes hair loss?

Alopecia areata (al-uh-PEE-shee-uh ar-ee-EY-tuh) causes round patches of hair loss. The skin in these areas looks smooth. The hair loss is usually fast, can happen at any age (mostly in young adults), and is more common in people with certain illnesses (such as diabetes and thyroid disease).

Tinea capitis (TIN-ee-uh CAP-uh-tiss) also causes round patches of hair loss. The skin in these areas looks dry, red, and scaly. There may be swollen lymph nodes at the back of the lower head. It is caused by a fungal infection (scalp ringworm).

With telogen effluvium (TELL-o-gin eh-FLOO-vee-um), you may lose 30 to 50 percent of your hair all at once. It often happens after a major stress on the body. This stress may be a severe illness, injury, crash diet, or extreme mental stress. Your hair will usually grow back.

Anagen effluvium (ANN-uh-gin eh-FLOO-vee-um) is a sudden loss of 80 to 90 percent of your hair. It happens when the growing phase of your hair is interrupted. It often happens in people with cancer who are receiving chemotherapy.

Other causes of hair loss include certain medicines, low levels of iron in your blood, poor nutrition, pregnancy (after childbirth), syphilis, thyroid disease, and repeated hair twisting.

Can my hairstyle cause it?

Wigs, tight braids, hair weaves, and the use of hair curlers can damage hair and lead to hair loss. Hair processing (such as bleaching, coloring, and perming) can also damage hair and cause hair loss. Your hair will usually grow back once you stop stressing your hair. In certain cases, it can lead to scarring and permanent hair loss.

How is it treated?

Many times hair will regrow on its own. Sometimes changing how you style or treat your hair can help. Getting rid of stress in your life can also help. Other treatments include changing your diet, correcting any hormone imbalances, switching medicines, treating infections, or getting shots into your scalp.

Minoxidil (Rogaine) is an over-the-counter medicine that is used to slow hair loss. There are other medications for men that must be prescribed by a doctor. It can take three to six months before you see the medicine start to work. When you stop taking these medicines, you lose any positive effects of treatment after six to 12 months. If treatment doesn't work or is not available for your type of hair loss, you may want to consider wearing a wig, hairpiece, hair weave, or artificial hair replacement.

Where can I get more information?

Your doctor

American Academy of Family Physicians

The American Hair Loss Council

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