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Patient Information Leaflet

Seborrhoeic dermatitis

What are the aims of this leaflet?

This leaflet has been written to help you understand more about seborrhoeic dermatitis.  It tells you what it is, what causes it, what can be done about it, and where you can find out more about it.

What is seborrhoeic dermatitis?

The words ‘dermatitis’ and ‘eczema’ mean the same thing and are interchangeable.  This leaflet could just as easily have been called ‘seborrhoeic eczema’.  For simplicity the word ‘dermatitis’ will be used here.

‘Dermatitis’ means an inflammation of the skin: ‘seborrhoeic’ simply means that the rash commonly comes up in areas rich in sebaceous (grease) glands such as the side of the nose, forehead and scalp.

Seborrhoeic dermatitis is harmless and very common, affecting as much as 3% of the population.  It is common in young adults, peaks at the age of forty, and is less common in old age.  It can occur in Infants, but then it usually clears up over the course of a few months.

What causes it?

This is not fully understood.  Seborrhoeic dermatitis does best with treatments that attack the yeasts that live on the surface of everyone’s skin.  This suggests that these skin yeasts play a part in causing it.  They are not the same as the yeasts that cause thrush or those that are present in foods.

Seborrhoeic dermatitis usually affects people who are otherwise well.  However, it is particularly likely to occur in people who have Parkinson’s disease, and can be severe in people who have a human immunodeficiency virus (HIV) infection, in whom the yeasts are able to grow unchecked.  However, seborrhoeic dermatitis itself is not infectious.

Tiredness and stress can sometimes trigger a flare of seborrhoeic dermatitis.  It is more common in cold than in warm weather, and it is not related to diet.

Is it hereditary?

This is not known.

What are the symptoms of seborrhoeic dermatitis?

Seborrhoeic dermatitis of the scalp is the commonest cause of dandruff and it can be itchy or sore.  The redness and scaling can be particularly embarrassing when it occurs on the face. 

What does it look like?

The rash is made up of red areas covered with greasy-looking white or yellowish scales.  Most commonly, the rash involves just one or two areas, but it can sometimes be extensive.  Seborrhoeic dermatitis occurs most often:

• On the scalp: seborrhoeic dermatitis here ranges from a mild dandruff to a redder, scalier and sometimes weeping rash, which may involve the adjacent parts of the forehead and around the ears.  Cradle cap in infants may be a feature of seborrhoeic dermatitis.
• On the face: it often affects the inner parts of the eyebrows, the creases beside the nose and adjacent parts of the cheeks. The eyelids may also become red and irritable (blepharitis).
• In and around the ears:  some people have inflammation inside the ear canals, in the cup of the ear and behind the ears.  The skin often oozes and crusts in these areas and the ears may swell..  Inflammation in the ear canal (otitis externa) can cause it to become blocked. 
• On the front of the chest and between the shoulder blades: it shows up as well-defined, roundish red patches that are sometimes scaly.
• In the flexures: it often affects moist areas such as the skin under the breasts, in the groin, under the arms, or in folds of skin on the abdomen.  In infants, the nappy area is commonly affected

How is it diagnosed?

Your doctor will usually be able to make the diagnosis by the look of the rash. No tests are normally necessary and a skin biopsy is seldom needed. 

However, the most common difficulty for doctors is distinguishing seborrhoeic dermatitis from psoriasis.  Psoriasis of the scalp usually comes up in well-defined rather redder patches, with a whiter, thicker type of scaling.   Sometimes the two conditions seem to overlap.  If there is any suspicion of scalp ringworm (a fungus infection), your doctor will send a specimen of the scales for culture

Can it be cured?

Treatment keeps seborrhoeic dermatitis under control, but does not cure it once and for all.

How can it be treated?

Remember that treatment suppresses seborrhoeic dermatitis rather than cures it, and that it often comes back after treatment has stopped.  You may therefore have to use treatments for months or even years. For this reason, they must be safe in the long term. The choice of treatment also depends on which parts of the skin have the rash: 

• In the scalp: for dandruff, medicated shampoos containing agents such as zinc pyrithione, selenium sulphide or ketoconazole can be used regularly.  Leave them on for 5 to 10 minutes before rinsing them off.  If dense scales cover the scalp, remove these first with warm olive oil.  Sometimes a scalp application containing a mild steroid can help reduce itching and redness. Alternatively a salicylic acid-based ointment can be rubbed in at night and washed off in the morning.
• Elsewhere: mild steroid creams with or without an antibacterial and/or antifungal component are usually effective.  Alternatives include ketoconazole cream, and sulphur/salicylic acid mixtures.  Washing your face daily with an antifungal shampoo containing ketoconazole may also help. Medicated eardrops may help affected ear canals: sometimes an ENT (ear, nose and throat) specialist may be needed to clean and pack them.

Occasionally, if the rash is widespread or resistant to the treatments listed above, your doctor may suggest a short course of an anti-yeast tablet such as itraconazole.

What can I do?

Once your scalp is clear, continue using an anti-fungal shampoo once a week to reduce the possibility of the rash coming back.  If you don’t like the thought of using prescribed antifungal or steroid creams, a plain moisturiser available over the counter, such as aqueous cream, may help to reduce scaling and redness.  Changing your diet is not likely to make any difference.

Where can I get more info rmation about it?

Web links to detailed leaflets:

www.aafp.org/afp/20000501/2703.html

www.emedicine.com/derm/topic396.htm

www.dermnetz.org/dna.sd/sd.html

The British Skin Foundation fund vital research into all skin diseases.  To find out how you can help, please visit the British Skin Foundation website here.

(While every effort has been made to ensure that the information given in this leaflet is accurate, not every treatment will be suitable or effective for every person. Your own doctor will be able to advise in greater detail).

BRITISH ASSOCIATION OF DERMATOLOGISTS
PATIENT INFORMATION LEAFLET
PRODUCED JUNE 2008