Seborrhoeic Dermatitis

What is seborrhoeic dermatitis?

Seborrhoeic dermatitis is a frequent, long-lasting inflammatory rash. It favours areas rich in oil (sebaceous) glands, above all the scalp, face and upper chest. On the scalp, dandruff is its mildest form.

Who gets it?

It can begin at any age, most often in the 30s, and men are affected a little more often than women. Dandruff, its mildest form on the scalp, affects nearly half of all adults. A separate, short-lived form, often called cradle cap, occurs in babies. Seborrhoeic dermatitis is more common and can be more severe in people with conditions affecting the nervous system, such as Parkinson's disease, and in people with a weakened immune system, including HIV.

What causes it?

The exact cause is not fully understood. It is linked to an inflammatory reaction to a yeast called Malassezia, which normally lives on everyone's skin. People with seborrhoeic dermatitis seem to react more strongly to it. Differences in the skin barrier and an increased sensitivity to oleic acid, a substance released when the yeast breaks down skin oils, are thought to trigger the inflammation.

It tends to be worse in cold, dry weather, at times of stress or illness, and with lack of sleep, and often improves in summer.

Is it hereditary or contagious?

Some people seem to inherit a tendency to the condition, and flares happen when this interacts with outside triggers. It is not contagious and is not caused by poor hygiene or an allergy.

What does it look and feel like?

Seborrhoeic dermatitis causes patches of red or darker skin covered with greasy, yellowish or white scale. It can be itchy, and the skin may feel sore or burning. In brown and black skin, affected patches may look paler or darker instead of red, and near the hairline they can take on a curved or ring-like shape.

Typical sites are the scalp and hairline, eyebrows, folds at the side of the nose, cheeks, in and around the ears, beard area, eyelid edges (blepharitis), mid-chest and the skin between the shoulder blades. It can also affect skin folds such as the armpits, groin and under the breasts.

How is it diagnosed?

It is usually diagnosed from its appearance and distribution. Occasionally it can look similar to psoriasis, rosacea or a fungal infection, and in that case further tests such as skin scrapings may be helpful.

What are the treatment options?

Dr Mounsey will confirm the diagnosis and rule out conditions that can look similar, such as psoriasis or rosacea. Treatment aims to reduce the yeast on the skin and calm inflammation. Options include antifungal shampoos and creams such as ketoconazole or Dercos, used regularly to keep the condition under control, along with short courses of mild steroid or calcineurin inhibitor creams for flares. Scalp scale can be softened with medicated oils or shampoos. For more troublesome cases, antifungal tablets may occasionally be considered. He will give you a simple maintenance plan to reduce the frequency of flares.

What is the outlook?

Seborrhoeic dermatitis is a long-term condition that tends to come and go. It cannot be cured, but it can be well controlled, and flares can be kept to a minimum.

More information

British Association of Dermatologists patient leaflet: https://www.bad.org.uk/pils/seborrhoeic-dermatitis

This page gives general information only and is not a substitute for a consultation. Everyone's skin is different, and what is right for you will depend on your own circumstances. If you are worried about a skin problem, please book an appointment with Dr Mounsey or speak to your GP. If you have a mole or skin lesion that is changing, bleeding or growing quickly, please seek medical advice promptly.