Seborrheic dermatitis is an inflammatory rash that causes skin to become red, dry and itchy. Commonly scales are formed that are white or yellow in areas of the body that are oily such as the scalp, inside the ear or the folds next to the nose. However, seborrheic dermatitis can also occur in the armpits, chest or groin area.
People with seborrheic dermatitis have an overproduction of oil (sebum) from their sebaceous glands. It is thought that their bodies develop an overactive immune response to normal levels of Malassezia yeast present on the skin causing the scales, flakes and inflammation. Many people with seborrheic dermatitis have dandruff, which can appear not just on the scalp but also on the eyebrows, in the inner ear even on eyelashes. Dandruff is considered to be a mild form of seborrheic dermatitis and occurs in 15 – 20 percent of the population. (2)
Seborrheic dermatitis is aggravated by stress, changes in season and excess scratching. It typically starts in puberty and reaches a peak of severity by age 40, then lessens in intensity as the person grows older. In infants, a version of seborrheic dermatitis is called cradle cap and can be very gently treated using baby shampoos or by first using small amounts of oil to loosen flakes followed with a shampoo. Cradle cap usually disappears on its own when the infant reaches 6 to 12 months of age.
Seborrheic dermatitis is first treated in adults using common dandruff shampoos containing zinc pyrithione such as Head and Shoulders, selenium sulfide such as Selsun Blue or ketoconazole. Other shampoos that use salicylic acid, coal tar and sulfur may be tried. Usually people rotate between different shampoos. It is important to follow the directions closely and leave the shampoo on the skin or scalp for several minutes before rinsing.
If shampoos do not offer enough help, a prescription cortisone cream may be prescribed but chronic treatment with steroid creams can lead to other changes in the skin. Thick scaly areas from seborrheic dermatitis can be softened overnight using some type of oil which is washed off in the morning with either a dandruff or coal tar shampoo.