Types and Causes of Hair Loss

• Alopecia areata – This condition can happen to anybody, but it's more likely to happen to kids and young adults. For unknown reasons, the immune system attacks the hair follicles, which is where the hair starts growing. The hair loss can range from bald patches to total loss of hair all over the body.
• Androgenic alopecia – Also called "male-pattern" or "female-pattern" hair loss, this is the most common type. If you have it, you can blame your genes, which you get from your mother and father's sides of the family. A form of the male hormone testosterone causes the follicles to shrink and stop growing hair. Men have more of this hormone, but some women have enough to cause their hair to thin. The older a man gets, the more likely he is to have hair loss. By age 50, about half of men have male-pattern hair loss – bald spots at the front of the scalp, at the temples or on top of the head. Overall, about 20 percent to 30 percent of women suffer from hair thinning. In women, thinning usually occurs over the entire head, rather than in spots.
  
  
• Hairstyles, cosmetic treatments and devices – Tight ponytails and braids, as well as hair extensions, can pull the hair out, or break it off. Using hairdryers and curling irons too much also can cause the problem. So can changing the hair color (bleaching or dying), straightening the hair (with chemicals or flat irons) or getting a perm to make hair curly.
• Scalp ringworm – Ringworm is a fungal infection that leads to red, swelling, oozing patches and causes hair to break off. It most commonly occurs in children.
• Telogen effluvium – Normally, 80 to 90 percent of the hair follicles on the head are busy growing hair. When the percentage of follicles producing hair drops significantly and quickly, it is called telogen effluvium. The condition is more likely in adults and can occur because of illness, pregnancy, trauma, chemotherapy or surgery. It can be triggered by hormone changes, such as pregnancy, or certain medications. Some researchers think it also can be caused by a sudden shock, stress or radical diets.

Other things, such as infections and vitamin deficiency, can cause hair loss too. If you're concerned see a dermatologist.

If your child wants to know about hair loss, he or she can visit Hair Loss .

Next: Treating Hair Loss

Photo references:

Alopecia areata and Ringworm: Photos used with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides.

Androgenic alopecia: This photo was previously published in the Journal of the American Academy of Dermatology, 2001 Sept;45(3):S70-S80. Olson, Elise. “Female pattern hair loss.” Copyright Elsevier (2001).