What is dandruff?
Dandruff (also known as seborrheic dermatitis) is a scalp condition, usually chronic, in which skin on the scalp forms flakes that are then shed from the scalp. These flakes consist of dead cells, and while it is normal for dead cells to be shed, with dandruff, a large number of these cells are shed at a faster rate than normal and become visible in the hair and on clothing. The cause of dandruff is not well known; some individuals consider it related to variations in hormone production.
Is dandruff contagious?
No, dandruff is not contagious or infectious. However, dandruff may get worse if certain yeasts and/or fungi that normally occur in small numbers on the scalp are increased in numbers. The increase in these microbes can contribute to increased flaking in dandruff. Because most of these organisms are already present on the skin, they are not considered to be contagious causes of dandruff.
However, another term that modifies the word dandruff is walking dandruff. This skin condition is usually seen in dog skin infected with small mites. These mites can be transmitted to other animals, including humans; consequently, walking dandruff in dogs, cats, and other animals can be contagious to humans. Walking dandruff in animals (and in humans) can be cured with topical medication to kill mites. This is in no way related to the dandruff that is commonly seen on the scalp of many individuals.
How will I know if I have dandruff?
A person will know they have dandruff if they see whitish, dry-appearing thin flakes in their hair, on their scalp, or on their clothing. Itching of the scalp may also be associated with dandruff. Some symptoms and signs of dandruff may improve after a reduction of stress; others may have a reduction in symptoms and signs during the summer months. Usually, a person does not need a medical caregiver to diagnose dandruff.
What causes dandruff?
Because the cause of dandruff is unclear and dandruff is not considered to be contagious, the only spread of dandruff is usually on the person's body. In most individuals, dandruff is confined to the scalp. However, dandruff may spread in an individual by occurring all over the scalp and may occur in other areas on the skin (for example, nasal folds on the face).
Treatment of seborrhea (dandruff) is directed at fighting the skin inflammation. This is done either directly, by using cortisone-based creams and lotions (which reduce inflammation), or by using topical anti-yeast lotions and shampoos.
How to get rid of dandruff: remedies
Although there is no cure for dandruff, people can reduce and practically eliminate the symptoms and signs associated with dandruff; some obtain good results with over-the-counter dandruff shampoos that contain zinc pyrithione, salicylic acid or selenium sulfide. However, these shampoos are not a cure for dandruff because such shampoos only cause smaller and less visible flakes to be shed. Frequent washing even with regular shampoo may also reduce dandruff symptoms and signs.
If yeast/fungi that occur normally on skin or scalp are contributing to dandruff symptoms and signs, some doctors recommend 1% ketoconazole (Nizoral shampoo) to reduce symptoms, although there is no credible evidence that this prescription shampoo works better than the over-the-counter variety.
When should I contact a medical caregiver about dandruff?
Most people do not need to contact a medical caregiver about dandruff. However, if itching is increasing and is associated with dandruff, if dandruff shampoo fails to reduce dandruff symptoms, or if inflammation (skin or scalp redness and swelling) and severe skin shedding occurs, contact a physician.
Medically reviewed by Norman Levine, MD; American Board of Dermatology
"Dandruff." University of Michigan Student Life University Health Service.