Seborrhoeic dermatitis is a common, benign skin problem which can affect infants, teenagers and adults. It causes the skin to be red, greasy, flaky and itchy. On the scalp, it is also known commonly as dandruff. Seborrhoeic dermatitis can also affect areas such as the face, ears, groin, chest and back.
In infants, seborrhoeic dermatitis can cause thick, scaly patches on the scalp. This is also known as cradle cap. Application of olive oil one to two hours before rinsing off with a mild shampoo can be helpful in removing the scales. Seborrhoeic dermatitis may only affect the diaper area and needs to be distinguished from other types of diaper rashes. Infants will usually outgrow this condition.
Seborrhoeic dermatitis often causes scalp dandruff, it can also affect other oil-gland rich areas such as the eyebrows, sides of the nose, cheeks, ear canals, chest and back. The affected areas are pink with greasy scales. While this condition is not harmful, it is often annoying and tends to recur, even after treatment.
Fig.1 Seborrhoeic dermatitis of the face
The cause is not fully known. It is common in people with oily skin and hair. It is thought that the yeast Malassezia multiplies in the oil glands, leading to inflammation (redness and itching) and overproduction of skin cells (scaling). Most cases appear for no obvious reason. However, people with immune system disorders e.g. HIV infection, neurological diseases such as Parkinson’s disease, stroke, heart disease, or under stress are more prone to this condition and may have more severe symptoms. Winter climate and stress can cause a flare.
The condition has characteristic features and occurs in typical sites. Mild cases may only have dandruff, sometimes with scaling at the ear canals or behind the ears. Your dermatologist can help you make the diagnosis.
Seborrhoeic dermatitis can mimic other scaly red skin conditions such as psoriasis, eczema, fungal infection of the skin and scalp (ringworm), rosacea, lupus and a drug rash. Skin scraping and biopsy, as well as blood tests may be performed if the rash is extensive and does not respond to treatment.
While there is no cure or prevention for seborrhoeic dermatitis, treatment can control this condition and improve symptoms. Medications are generally anti-fungal, anti-inflammatory or keratolytic (remove scales).
Scalp seborrhoeic dermatitis is treated by shampooing two to three times a week with an anti-dandruff shampoo, such as selenium sulphide, coal tar, cetrimide, zinc pyrithione or ketoconazole. Olive oil or cocois ointment may be applied one to two hours before shampooing or left overnight to remove thick scales.
For seborrhoeic dermatitis of the body or face, cleanse twice daily with a gentle soap; a mild steroid or antifungal cream can be used for skin rashes. Steroid creams should be used sparingly as they may cause thinning of the skin. For very severe, persistent seborrhoeic dermatitis, your doctor may prescribe a course of antifungal tablets.