Seborrheic Dermatitis: What causes it and how do we treat it?
Seborrheic dermatitis is a red, scaly, skin and scalp condition that affects both children and adults. The condition is extremely common. Estimates suggest that up to 3-5 % of the world is affected by the condition. Infants can be affected by seborrheic dermatitis, and this is typically called 'cradle cap.' During pre-pubertal years the incidence of seborrheic dermatitis reduces significantly until it spikes again in adolescence. Adults can be affected and the incidence increases again in the 60s and 70s.
Seborrheic dermatitis is thought to be caused by a variety of factors. However, central to all these factors is the presence of a yeast known as Malassezia and some local or systemic alteration in the immune system. Malazzesia yeast are thought to help metabolize certain types of fats in the skin from non irritating to irritating and inflammatory fatty acids that cause inflammation. It's clear that getting rid of these yeast helps control the symptoms and signs of seborrheic dermatitis. Most individuals with seborrheic dermatitis have a healthy immune system. However, it's clear that there is some alteration in the skin immune system that prevents these individuals from eradicating the Malazzesia yeast.
Risk Factors for Seborrheic Dermatitis
Some patients develop seborrheic dermatitis for no clear reason. These individuals likely have an underlying predisposition to the condition. However, it is now clear that there are a number of risk factors for seborrheic dermatitis, including neurological disease (Parkinson's disease, traumatic brain injury), depression, organ transplantation, HIV/AIDS, alcoholic pancreatitis, intense stress.
Signs and Symptoms of Seborrheic dermatitis
Seborrheic dermatitis can affect both the scalp and the skin. Patients may be completely asymptomatic or notice varying degrees of scalp itching, redress, flaking and scaling. The scalp may become greasy with patients feeling that more frequent shampooing just makes things feel better. The eyebrows can also be affected by redness and flaking. Many patients with seborrheic dermatitis have red flaky patches arund the nose, on the mid-chest and even back.
Treatment of Seborrheic Dermatitis
There is no cure for seborrheic dermatitis but there are treatments that can help reduce the frequency and severity of flares. In other words, appropriate treatment, can help make it appear that patients have minor disease or no disease at all. However, periodic use of anti-fungal and anti-inflammatory agents may be needed to keep the condition under control.
There are a variety of treatments of Seborrheic dermatitis. Eradicating the Malasezia yeast appears to be important in the treatment. For this reason, I generally recommend use of various anti-dandruff shampoos including those containing zinc pyrithione, selenium sulphide, ketoconazole, and ciclopirox. These should be left on the scalp for 1-5 minutes depending on the specific patient's scalp. Anti-dandruff shampoos can be drying, and so careful monitoring is needed to determine how best to use these for any given patent.
A variety of natural products can also help seborrheic dermatitis. Tea tree oil is among the most helpful of the natural products and is available in a variety of shampoo formulations.
Corticosteroids can sometimes be used but are generally not first line agents for most with mild cases of seborrheic dermatitis. However, use of corticosteroid shampoo (such as Clobex) or mild corticosteroid lotions (including periodic use of betamethasone valerate lotion of foam) during times of flares can help many to achieve remission and feel better.
Oral agents including retinoids (isotretinoin) and oral anti-fungal agents (itraconazole) are reserved for more challenging cases of seborrheic dermatitis that is unresponsive to conventional treatments.
Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Whistler office at 604.283.1887