What is seborrhoeic dermatitis?

Dr Haran Sivapalan
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What is Seborrhoeic Dermatitis (seborrhoeic eczema)?

Seborrhoeic dermatitis (also known as seborrhoeic eczema) is a type of rash causing scaling and inflammation of the skin. Commonly affected areas include the face, scalp, groin and armpits. The affected areas of skin appear red, flaky and greasy. When the scalp is affected, it also causes dandruff.

It quite commonly affects babies  (infantile seborrhoeic dermatitis) and is known as cradle cap. In this case it presents as brown or yellowish plaques, mostly on the scalp or forehead.

It is an inflammatory conditions that affects up to 5% of the population. It is not related to diet, cleanliness or dryness of the skin. It is not infectious and cannot be spread from one person to another.

 

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The main symptom of seborrhoeic dermatitis is a rash with patches of inflamed, red and greasy-looking skin. The skin also has flaky, fine scales. Patches tend to be circular or oval and a few centimetres wide. There may also be a yellow-brown crust on top of each patch, particularly for patches on the scalp.

The most commonly affected areas include the:

  • Scalp
  • Forehead
  • Face – particularly:
    • Nasolabial folds –the skin around the lines that extend from the edge of the nose to the corners of the mouth.
    • Bridge of the nose
    • Eyelids – eyelids may become red, sore and flaky.
  • Ears – particularly the skin folds behind the ear
  • Chest
  • Armpits
  • Groin

Dandruff is a symptom of seborrhoeic dermatitis that affects the scalp. In milder cases of the condition, dandruff may be the only symptom. In more severe cases, there is an accompanying rash and itchiness.

Seborrhoeic dermatitis affecting the chest may cause small (less than 1cm wide) raised spots of skin that are red. These are known as papules.

 

The exact cause of seborrhoeic dermatitis is unknown. It is thought to be an inflammatory reaction to a yeast called Malassezia spp. The yeast (which is a type of fungus) normally lives on the skin, particularly in the sebum – an oily substance on the surface of the skin. In most people, the yeast is harmless and does not cause any problems.

In people with seborrhoeic dermatitis, the body may trigger an inflammatory response to the Malassezia yeast, causing the development of rash with redness and scales. As the yeast lives in sebum (which is produced by the skin’s sebaceous glands), seborrhoeic dermatitis tends to affect areas of skin that are rich in sebaceous glands e.g. scalp, forehead, armpits.

 

Seborrhoeic dermatitis is more common in people with:

  • HIV / AIDS – people with HIV/AIDS tend to develop more severe seborrhoeic dermatitis. This may be due to an altered immune system response to the Malassezia yeast.
  • Parkinson’s disease – Parkinson’s disease causes immobility, which may cause sebum and numbers of Malassezia yeast to build up on the skin.

Seborrhoeic dermatitis is unrelated to diet, cleanliness or dryness of the skin. It is not infectious and cannot be spread from one person to another.

Certain events may trigger seborrhoeic dermatitis or exacerbate an existing episode of the rash. These include:

  • Psychological stress
  • Tiredness
  • Cold weather
  • Certain medications – including buspirone (an anti-anxiety medication), lithium, cimetidine (a medication used in acid reflux and stomach ulcers) and haloperidol (an antipsychotic medication).

It is not known exactly how these factors trigger seborrhoeic dermatitis.

A GP can diagnose seborrhoeic dermatitis from a simple examination of the skin. Further investigations are not usually required.

Referral to a dermatologist

Your GP may refer you to a dermatologist in the event seborrhoeic dermatitis is severe and widespread, or is unresponsive to treatment.

Treatment of seborrhoeic dermatitis aims to reduce the amount of Malassezia yeast on the skin. Malassezia yeast is a type of fungus, and so is destroyed by anti-fungal medication applied directly to the skin. Creams and shampoos containing anti-fungal medication thus form the mainstay of treatment for seborrhoeic dermatitis.

Treatment of scalp

For seborrhoeic dermatitis affecting the scalp, any crusts and scales will first need to be removed before applying antifungal cream. This can be done by applying warm olive oil to scalp and leaving it soak for several hours, before washing it off with a normal or coal tar shampoo. Salicylic acid or coal-tar shampoo may be used instead of olive oil.

For cradle cap in babies, applying baby oil olive oil or vaseline to the scalp and leaving it overnight can help lift the plaques. It is important not to pick at the plaques.

Alongside antifungal creams and shampoos, a GP may also want to prescribe a steroid cream, in order to reduce inflammation of the skin.

Anti-fungal creams

Anti-fungal creams include ketoconazole, clotrimazole, econazole and miconazole creams. They are usually applied to the skin once or twice a day for a period of 4 weeks. Studies show the different anti-fungal creams to be equally effective at treating seborrhoeic dermatitis.

After the rash has cleared, your GP may instruct you to continue applying cream, but at less frequent intervals (e.g. twice a week). This is to prevent the rash from coming back.

 

Anti-fungal shampoo

Anti-fungal shampoos are used to treat seborrhoeic dermatitis affecting the scalp, eyebrows and beard. They are usually applied twice a week over the period of a month. After the rash has cleared, it is suggested to use anti-fungal shampoo once every week or two weeks to prevent seborrhoeic dermatitis from recurring.

There are two main types of anti-fungal shampoo available. The first line choice is usually 2% ketoconazole shampoo. As an alternative the GP may prescribe selenium sulphide shampoo. Both these medications are available on prescription or over the counter at a pharmacist.

For adolescents and adults with seborrhoeic dermatitis affecting the body, anti-fungal shampoo may also be used as a body wash. For effective treatment, however, an anti-fungal cream is still required in addition to the shampoo.

Other medicated shampoos

Dandruff may be treated using other medicated shampoos, such as those containing zinc pyrithione (e.g. Head and Shoulders), coal tar or salicylic acid.

 

Oral anti-fungal medication

For severe cases of seborrhoeic dermatitis, or cases that do not respond to topical creams and shampoos, a doctor may consider prescribing an antifungal medication that is taken orally. Oral antifungals have the potential to cause serious side effects (e.g. liver damage), so you may require blood tests to monitor these effects.

 

Topical corticosteroids

Topical corticosteroids include hydrocortisone, betamethasone and mometasone creams. They are prescribed alongside antifungal creams/shampoos in order to reduce inflammation and itching of the skin.

When there is severe itching of the scalp, a potent corticosteroid cream (e.g. 0.1% betamethasone) can be applied for up to 4 weeks. They are not recommended for long-term use, as they can cause side effects such as thinning of skin. Similarly, they are not recommended for use on the face or beard.

Milder corticosteroid creams, such as 0.5% hydrocortisone cream, may be used for seborrhoeic dermatitis affecting the face or body. They are applied to the inflamed skin once or twice daily for 1-2 weeks.

Topical calcineurin inhibitors

Topical calcineurin inhibitors include drugs such as tacrolimus and pimecrolimus creams. These work by dampening down the inflammatory response in the skin. They are currently not licensed for use in seborrhoeic dermatitis, but a GP may prescribe them if they feel it will produce a beneficial effect. Studies have shown calcineurin inhibitors to be as effective as antifungal and steroid creams.

 

Continue using antifungal shampoo after symptoms have cleared

Your GP may advise you to continue applying antifungal shampoo or cream after the symptoms of seborrhoeic dermatitis have disappeared. It is important to do this to prevent the rash from reappearing.

 

Avoid cosmetic products containing alcohol

Cosmetic products containing alcohol should be avoided where possible. This is because alcohol can aggravate inflammation of the skin.

Avoid soap and shaving foam on the face, if necessary

Soap and shaving foam can irritate the skin of some people with seborrhoeic dermatitis. Emollient or emollient soap substitutes can be used instead.

Avoid stress

Stress can trigger seborrhoeic dermatitis and, where possible, should be avoided.

Kastarinen, H., Oksanen, T., Okokon, E. O., Kiviniemi, V. V., Airola, K., Jyrkkä, J., … & Verbeek, J. H. (2014). Topical anti‐inflammatory agents for seborrhoeic dermatitis of the face or scalp. The Cochrane Library.

Okokon, E. O., Verbeek, J. H., Ruotsalainen, J. H., Ojo, O. A., & Bakhoya, V. N. (2015). Topical antifungals for seborrhoeic dermatitis. The Cochrane Library.

NICE CKS. Seborrhoeic Dermatitis (February 2013). Available online at: https://cks.nice.org.uk/seborrhoeic-dermatitis

Seborrhoeic dermatitis. Patient.info – Professional Reference Article. Available online at: http://patient.info/doctor/seborrhoeic-dermatitis-pro

Seborrhoeic dermatitis. Patient.info. Available online at: http://patient.info/health/seborrhoeic-dermatitis-leaflet