Dandruff Causes and Treatments

As anyone who has dandruff knows, it can be embarrassing to wear black tops when they get covered in unsightly white flakes. Fortunately, effective treatment for dandruff, known as seborrheic dermatitis, exists.

What Is Dandruff?

Dandruff is a mild form of what is known as seborrheic dermatitis, a common type of chronic dermatosis that usually affects areas of the body that contain abundant sebaceous glands like the scalp, face, chest and body folds.

Sebaceous glands secrete sebum, a waxy substance that lubricates hair and skin. Mild seborrheic dermatitis that affects the scalp is called dandruff (pityriasis sicca) and results in characteristic flaking. Of note, in infants, mild seborrheic dermatitis results in a condition called "cradle cap."

Dandruff can begin in childhood and has a gradual onset. The course of dandruff waxes and wanes with flare-ups and remissions common. Infantile and adolescent dandruff and seborrheic dermatitis can remit with age or continue through adulthood.

Dandruff and seborrheic dermatitis affect about 2 to 5% of the general population and is more likely to affect men. Some people complain that their dandruff worsens during the fall and winter or in dry environments. Moreover, sunlight has a variable effect on dandruff; some people think that sunlight improves their dandruff, and others think sunlight makes their dandruff worse.

Scaling typical of dandruff usually affects the entire scalp and can also affect eyebrows and eyelashes. This scaling is usually gray-white or orange-red in color and sloughs off of either flattened lesions (macules or patches) or raised lesions (papules). In addition to scaling, dandruff can also be dry and itchy, and inflammation is evident on histologic or microscopic examination.

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Causes

Some experts suggest that dandruff and, more generally, seborrheic dermatitis are caused by a genetic predisposition to a "seborrheic state." This seborrheic state may also be linked to a "pre-psoriasis state." In fact, many people with dandruff also have psoriasis on their trunks. (Psoriasis typically presents with silvery scales.) Comorbid presentation of seborrhea and psoriasis is so common that some have proposed the term "seborrhiasis."

In addition to genetics, the yeast Malassezia furfur may play a role in the development of both seborrhea and psoriasis.

Though common among healthy individuals, dandruff and seborrheic dermatitis are frequently associated with the following conditions:

• Parkinson's disease
• Immunocompromised states like HIV and AIDS and organ transplant
• Nutritional deficiencies of zinc, niacin, and pyridoxine

Of note, facial paralysis secondary to Parkinson's disease or other conditions may play a role in the development of dandruff.

Treatments

As you may be aware, shampoos are often used to treat dandruff. These shampoos are often available over the counter (think Head and Shoulders, T/Gel, Selsun Blue). Prescription shampoos like Nizoral, which contains 2% ketoconazole, also works well. The reason why an antifungal medication like ketoconazole may work well is because, as previously mentioned, dandruff may be caused in some part by yeast.

When using shampoo to treat dandruff, you should first wet your hair before application and then thoroughly rinse your hair after application. Other creams including tacrolimus, pimecrolimus, and hydrocortisone may also help relieve the discomfort of dandruff.

If you have certain thick plaques, they sometimes can be injected with cortisone at your dermatologist's office. Talk to your dermatologist about whether you're a candidate for this treatment.