Resources
National Institute of Arthritis, Musculoskeletal and Skin Diseases (NIAMS) National Institutes of Health 1 AMS Circle Bethesda, MD 20892-3675 Phone: 301-495-4484 or 877-22-NIAMS (226-4267) (toll free) TTY: 301-565-2966 Fax: 301-718-6366 E-mail: NIAMSInfo@mail.nih.gov Web Site: http://www.niams.nih.gov/ National Center for Complementary |
American Academy of Dermatology P.O. Box 4014 Schaumburg, IL 60168-4014 Phone: 847-330-0230 or 888-462-DERM (3376) (toll free) Fax: 847-330-0500 Web Site: http://www.aad.org/ National Alopecia Areata Foundation American Hair Loss Council |
Hair Loss: What Causes It?
Except for the palms of the hands, soles of the feet, genitals and lips, the human body is completely covered with hair follicles. Most follicles are tiny and many of the hairs they produce do not grow long enough to protrude from the pore. Hair is made mainly of a protein called keratin. The only living part of the hair is the bulb, which is anchored to the base of the follicle. The follicle supplies oxygen and nutrients to the bulb, and lubricates the hair shaft with an oily substance called sebum.
Hair grows in phases, with around one in ten head hairs ‘resting’ at any given time. The color, curl, length, thickness and amount of hair depend on genetic factors. There are many different causes of hair loss, but only those that damage the follicles can make the loss permanent. Breaking or damaging the hair shaft has no affect at all on the health of the bulb.
Alopecia areata
Alopecia areata is a disorder characterized by inflammation of the hair bulb, which shrivels and ultimately stops producing hair. Alopecia areata is an autoimmune disease, which means the immune system mistakenly attacks cells of the body, and in this case the hair bulb.
Typically, a small patch of hair (ranging from around 1/4″ to 1 1/4″ in diameter) drops out, leaving only a few stubbly hairs. In some cases, the hair starts to grow back within a few weeks or months, but other people are left with persistent bald spots. The scalp is most commonly affected, although facial and body hair can also be lost. Mild cases generally respond well to cortisone creams or injections, while for more severe forms oral tablets may be required. However, for a small proportion of people with alopecia areata, it is difficult to get the hair to regrow, and cosmetic options including wigs may need to be considered.
Male pattern baldness (androgenic alopecia)
The most common cause of hair loss in men is androgenic alopecia, or male pattern baldness. In men who have inherited the condition, testosterone, the male sex hormone, actively targets the hair follicles. Over time, the hair follicles and consequently the hair shaft is reduced until it is short, fine and downy. While there are a number of treatments available for male pattern baldness, there is no cure. Treatments include minoxidil lotion and finasteride medication which are available by prescription. Cosmetic options include wigs and hair transplant surgery.
Patterned hair loss in women (androgenetic alopecia)
Hair loss in women tends to produce thinning over the top of the scalp rather than a patch of baldness. Minor degrees of patterned hair loss occur in over 55 percent of women as they age. However, only about 20 percent of women develop moderate or severe hair loss. Women generally don’t suffer from androgenic alopecia because their levels of testosterone are too low to exert a damaging influence. Hormonal imbalances, the contraceptive pill or the effects of corticosteroids can be responsible for baldness in women. Other possible causes include iron deficiencies, or a diet low in protein and vitamins, and dietary supplements rarely if ever improve hair loss. Thyroid disease is a rare cause of patterned hair loss in women. A number of treatments are available for female pattern hair loss including topical minoxidil lotion and antiandrogen medication. These are available by prescription and require medical supervision.
Traction alopecia
Tight ponytails, plaits or buns can all result in patches of hair loss, usually around the scalp margins.
Trichotillomania
Sometimes people chew or pull on hair when they are nervous, in a stress response similar to nail biting.
Hair Weathering
Hair shafts can be broken by rough handling. Brushing too vigorously, rolling hair curlers too tightly, over bleaching, and the use of harsh dyes and chemicals can dry out the hair and make it brittle enough to split or break. The hair bulb is generally unharmed, and normal hair growth will resume with gentle handling and care.
Ringworm
Ringworm is a fungal infection of the skin, caused by the fungus microsporum or trichophyton. Usually, ringworm of the scalp starts as a small circle of red, itchy and scaly skin. As this ring grows, the hairs within its circumference snap off close to the scalp. Treatment options include antifungal antibiotics.
Chemotherapy
Chemotherapy refers to a course of cancer-killing drugs that are taken by cancer patients. One of the most common side effects of chemotherapy is hair loss. Once the chemotherapy is completed, the hair usually grows back.