Seborrheic Dermatitis (SD)
Seborrheic dermatitis (SD) is an inflammatory skin condition that affects 2% to 5% of the population and can occur from infancy through adulthood. The symptoms of SD vary with age.
Infants with SD
Infants with SD develop yellow or brown greasy scales that adhere to the scalp, a symptom called cradle cap. Up to 70% of newborns develop cradle cap within their first 3 months due to certain maternal hormones, and there is a slightly higher incidence in males than females. SD in infants can lead to accumulating scale which may be accompanied by inflammation and can become infected. The diaper area is commonly affected and SD is often mistaken for diaper rash. Some babies are bothered by red, scaly patches that cover a much greater portion of their body, but the condition tends to disappear between 6 months and 1 year of age.
Adolescents and Adults with SD
Adolescents and adults have what is called classic seborrheic dermatitis, otherwise known as dandruff. It is characterized by fine, dry, white scale on the scalp accompanied by minor itching. The skin beneath the scale may become inflamed. In some people scaling and inflammation are more widespread. Less commonly affected sites include the armpits, folds beneath the breasts, groin, and navel. Despite its unsightly appearance, SD is not the result of poor hygiene. Unfortunately, when adults are affected with SD, the condition can persist with flares that come and go throughout a person’s life. Luckily, treatment can offer relief and reduce flares.
Causes of SD
Several lifestyle issues are believed to increase the risk of developing SD. These include:
- Extreme weather
- Oily skin
- Infrequent shampooing or cleansing
- Lotions that contain alcohol
Certain medical conditions may also be associated with SD:
- Neurologic conditions, such as Parkinson’s disease, head injury, Alzheimer’s disease, spinal injuries, tardive dyskinesia, trigeminal nerve lesions, and stroke
- HIV, AIDS
- Mood disorders
It has been suggested that an immune response may predispose some patients to SD and that there is a tendency for it to run in families.