About seborrhoeic dermatitis
Seborrhoeic dermatitis is a common scaly rash that often affects the face, scalp, and chest, but it can affect other areas. ‘Dermatitis’ is another word for ‘eczema’. ‘Seborrhoeic’ (pronounced seb-or-a-ik) simply means that the condition appears in those areas of the skin with large numbers of grease (sebaceous) glands, such as the scalp and sides of the nose. The condition affects 1-3% of the adult population and is more common in men than women.
What causes seborrhoeic dermatitis?
Adult seborrhoeic dermatitis is believed to be an inflammatory reaction related to an overgrowth of normal skin inhabitants – species of Malassezia yeasts (Malassezia furfur, also known as Pityrosporum ovale). The yeasts are part of normal skin flora, but for an unknown reason they trigger seborrhoeic dermatitis in certain individuals. Seborrhoeic dermatitis is not contagious or related to diet, but it may be aggravated by illness, psychological stress, fatigue, changes of season and a general deterioration of health. Those with an immunodeficiency (especially infection with HIV), heavy alcohol intake, and neurological disorders such as Parkinson’s disease and stroke are particularly prone to it. It may or may not be itchy and can vary from day to day.
What does it look like?
Seborrhoeic dermatitis appears as faintly red areas of inflamed skin with a greasy-looking white or yellowish scale on the surface. In flexural areas such as the armpits or groin, the scale may be absent and the skin can look a bit more glazed. On more exposed areas, the scale can become quite marked and yellowish. It can be itchy and, if more severe, sore.
How is it treated?
Seborrhoeic dermatitis cannot be cured, because once an individual has become allergic to Malassezia on the skin, exposure to it will always cause a problem. The only way to keep it under control is to use anti-yeast treatments. However, it is usually not difficult to keep seborrhoeic dermatitis under control, and topical treatments are safe to use long-term.
Milder cases are often managed with over-the-counter remedies, and pharmacists should be able to advise on these. The major reservoir for the yeast is the scalp, so a medicated anti-yeast shampoo should be used. Even if all signs of the condition have disappeared, it is advisable to use an anti-yeast shampoo once a week as an ongoing preventative measure. After treating the scalp, it may still be dry, so emollients should be used.
For more information on seborrhoeic dermatitis in adults, please see our Seborrhoeic dermatitis factsheet