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Diseases and Conditions
Dandruff
From MayoClinic.com
Special to CNN.com

Introduction

If dandruff is the only thing standing between you and a closet full of basic black, you're not alone. At any one time, millions of Americans have this chronic scalp disorder, which is marked by itching and excessive flaking of the scalp. Although dandruff isn't contagious and is rarely serious, it can be embarrassing and surprisingly persistent.

The good news is that dandruff can usually be controlled. Mild cases may need nothing more than daily shampooing with a gentle cleanser. And stubborn flakes often respond to medicated shampoos. What's more, researchers have identified a yeast-like fungus that may cause or aggravate dandruff, a discovery that may lead to better treatments and even to a whole new wardrobe.

Signs and symptoms

For most people, the symptoms of dandruff are unmistakable: white, oily-looking flakes of dead skin that dot your hair and shoulders and an itchy, scaling scalp. But it's not quite that simple — many conditions cause excessive skin scaling, including:

  • Dry skin. Simple dry skin — the kind you get in winter when the air is cold and rooms are overheated — is by far the most common cause of itchy, flaking skin. But flakes from dry skin are generally smaller and less oily than those caused by dandruff.
  • Seborrheic dermatitis. This condition, a frequent cause of dandruff, is marked by red, greasy skin covered with flaky white or yellow scales. Seborrheic dermatitis affects not only your scalp but also other areas rich in oil glands, such as your eyebrows, the sides of your nose and the backs of your ears, your breastbone, your groin area, and sometimes your armpits.
  • Psoriasis. This skin disorder causes an accumulation of dead skin cells that form thick silvery scales. In severe cases, your skin cracks, bleeds and may be quite painful. Psoriasis commonly occurs on your knees, elbows and trunk, but it can also extend from your scalp onto your forehead and neck.
  • Cradle cap (seborrheic dermatitis of the scalp). This disorder, which causes a scaling, crusty scalp, is most common in newborns, but it can occur anytime during infancy. Although it can be alarming for parents, cradle cap isn't dangerous and usually clears up on its own by the time a baby is a year old.
  • Scalp ringworm (tinea capitis). This highly contagious fungal infection occurs primarily in children younger than age 10. Ringworm starts as a red sore around a hair shaft — usually on the scalp but sometimes in the eyebrows or eyelashes. Within a few days, the sore turns scaly and spreads outward in the ring pattern that gives the infection its name. The hair in the affected area usually breaks off just above the surface. Unlike dandruff, ringworm usually causes a red, inflamed scalp as well as hair loss.
  • Contact dermatitis. Sometimes sensitivities to certain hair-care products or hair dyes can cause a red, itchy, scaling scalp.

Causes

At one time or another, dandruff has been blamed on dry skin, oily skin, shampooing too often or not often enough, a poor diet, stress, and the use of too many fancy styling products. Although some of these factors may exacerbate or contribute to scalp flaking, the real culprit may be a fat-eating, yeast-like fungus called malassezia, formerly known as pityrosporum.

Malassezia lives on the scalps of most healthy adults without causing problems. But sometimes it grows out of control, feeding on the oils secreted by your hair follicles and causing irritation that leads to increased cell turnover.

All skin cells die and are replaced by new cells. Normally, it takes about a month for new cells to move from the lowest layer of your skin, where they form, to the outermost layer, where they die and scale off in flakes. Because cells renew themselves slowly, this process usually isn't noticeable.

But on scalps where malassezia thrives, the whole process can take as little as 11 days. The result is a large number of dead skin cells. As the cells fall off, they tend to clump together with oil from your hair and scalp, making them appear white, flaky and all too visible.

Exactly what causes an overgrowth of these organisms isn't known, although increased oil production, hormonal fluctuations, stress, illness, neurologic disorders such as Parkinson's disease, a suppressed immune system, infrequent shampooing, extra sensitivity to the malassezia fungus and even heredity may contribute to the development of dandruff.

Risk factors

Almost any adult is a candidate for dandruff, but certain factors can make you more susceptible:

  • Age. Dandruff usually begins at puberty — about the same time as acne. It's common throughout adolescence and young adulthood and peaks around age 40. But older adults aren't immune, and for some people, the problem can be lifelong.
  • Sex. Because far more men than women have dandruff, some researchers think male hormones may play a role in dandruff. Men also have larger sebaceous glands that produce an oil called sebum.
  • Oily hair and scalp. Malassezia feeds on oils in your scalp. For that reason, having excessively oily skin and hair makes you more prone to dandruff.
  • Certain illnesses. For reasons that aren't clear, adults with neurological diseases such as Parkinson's disease are more likely to develop seborrheic dermatitis and dandruff. So are people recovering from stressful conditions, particularly heart attack and stroke, and those with immune systems compromised by HIV infection or AIDS.

When to seek medical advice

Most cases of dandruff don't require a doctor's care. But if you're still scratching your head after several weeks of experimenting with over-the-counter (OTC) dandruff shampoos or if your scalp becomes red or inflamed, see your doctor or dermatologist. You may have seborrheic dermatitis or another condition that resembles dandruff. Most often, your doctor can diagnose the problem simply by looking at your hair and scalp.

Treatment

Dandruff is a chronic condition that can almost always be controlled, but it may take a little patience and persistence. In general, mild scaling can often be helped by daily cleansing with a gentle shampoo to reduce oiliness and cell buildup.

When regular shampoos fail, OTC dandruff shampoos may succeed. But dandruff shampoos aren't all alike, and you may need to experiment until you find one that works best for you. Dandruff shampoos are classified according to their active ingredient:

  • Zinc pyrithione shampoos (Suave Dandruff Control Shampoo, Head & Shoulders). These contain the antibacterial and antifungal agent zinc pyrithione, which has been shown to reduce the fungus that causes dandruff and seborrheic dermatitis.
  • Tar-based shampoos (Neutrogena T/Gel, Tegrin). Coal tar, a byproduct of the coal manufacturing process, helps conditions such as dandruff, seborrheic dermatitis and psoriasis by slowing cell turnover. But coal tar has an "earthy" smell, can give light-colored hair an orange tint and may make treated skin more sensitive to sunlight.
  • Shampoos containing salicylic acid (Ionil T). These "scalp scrubs" help eliminate scale, but they may leave your scalp dry, leading to more flaking. Using a conditioner after shampooing can help counter dryness.
  • Selenium sulfide shampoos (Selsun, Exsel). These shampoos help prevent cell turnover and may also reduce the number of malassezia. Because they can discolor blonde, gray or chemically colored hair, be sure to use them only as directed and to rinse well after shampooing.
  • Ketoconazole shampoos (Nizoral). The newest addition to the dandruff armamentarium, ketoconazole is a broad-spectrum antifungal agent that may work when other shampoos fail. It's available over-the-counter as well as by prescription.

Try using one of these shampoos daily until your dandruff is controlled, then cut back to two or three times a week. If one type of shampoo works for a time and then seems to lose its effectiveness, try alternating between two types of dandruff shampoos. Be sure to leave the shampoo on for at least 5 minutes — this allows the ingredients time to work. Some experts suggest lathering twice for best results.

If you've shampooed faithfully for several weeks and there's still a dusting of dandruff on your shoulders, talk to your doctor or dermatologist. You may need a prescription-strength shampoo or more aggressive treatment with a steroid lotion.

Self-care

You can't prevent dandruff, but you can take steps to reduce your risk:

  • Learn to manage stress. Stress affects your overall health, making you susceptible to a number of conditions and diseases. It can even help trigger dandruff or exacerbate existing symptoms.
  • Shampoo often. If you tend to have an oily scalp, daily shampooing to remove the excess oil may help prevent dandruff.
  • Cut back on styling products. Hair sprays, styling gels, mousses and hair waxes can all build up on your hair and scalp, making them oilier. Some people may even develop allergies to various hair-care products.
  • Eat a healthy diet. For overall good health, include plenty of fresh fruits and vegetables, whole grains, and small amounts of lean protein in your diet.
  • Get a little sun. Sunlight may be good for dandruff. But because exposure to ultraviolet light damages your skin and increases your risk of skin cancer, don't sunbathe. Instead, just spend a little time outdoors. And be sure to wear sunscreen on your face and body.

Complementary and alternative medicine

There are plenty of home remedies for dandruff: rubbing a cut onion on your head, massaging your scalp with three-day-old cheese, rinsing with vinegar. Some may actually help, but they leave a lot to be desired, aesthetically speaking. That's why most complementary approaches focus on treating the problem from the inside out — with diet and nutritional supplements. Here are some of the most common suggestions:

  • Limit sugar and yeast. Sweets and yeast-containing foods such as bread, beer and wine may encourage the growth of the fungus that causes dandruff.
  • Emphasize B vitamins. These are essential for healthy skin and hair. Good food sources include whole grains, egg yolks, soybeans, bananas, avocados, nuts and seeds, and dark leafy greens, such as spinach. B-vitamin supplements are available in natural foods stores and many drugstores.
  • Include zinc in your diet. The mineral zinc, found in some dandruff shampoos, helps regulate the activity of your oil glands, keeps your immune system healthy and promotes healing. It's best to get zinc from food sources such as egg yolks, fish — especially sardines — meat, soybeans, sunflower seeds and whole grains.
  • Get plenty of omega-3 fatty acids. Sometimes known as essential fatty acids, these oils are necessary for good health. Among other things, they aid in the transmission of nerve impulses, help produce new cells and lower cholesterol levels. They also help keep your skin and hair healthy. Omega-3 fatty acids are found primarily in fresh, deep-water fish — especially salmon, swordfish, mackerel and herring — and in canola, soybean, fish and flaxseed oils. In addition, many natural foods stores and drugstores carry a variety of fish and vegetable oil supplements.
  • Try a tea tree oil shampoo. Tea tree oil, which is extracted from the leaves of the Australian tea tree (Melaleuca alternifolia), has been used for centuries as an antiseptic, antibiotic and antifungal agent. It's now included in a number of shampoos found in natural foods stores. The oil can cause allergic reactions in some people, so be sure to stop using it if you have any problems.

December 14, 2004

© 1998-2006 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "Mayo Clinic Health Information," "Reliable information for a healthier life" and the triple-shield Mayo logo are trademarks of Mayo Foundation for Medical Education and Research.  Terms of Use.

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