Seborrhoeic dermatitis

What is seborrhoeic dermatitis?

Seborrhoeic dermatitis is a type of skin rash. It is sometimes called seborrhoeic eczema. It most often occurs in young adults but can occur at any age. About 1-3 in 100 adults develop this condition. It is more common in men than in women.

Some babies have a similar condition that usually clears within a few months which is sometimes called cradle cap. See the separate leaflet called Seborrhoeic Dermatitis in Babies (Cradle Cap) for more details.

Dermatitis means inflammation of the skin, and seborrhoeic means it affects the areas where there are sebaceous glands. These are the glands that make the oil (sebum) for the skin.

Seborrhoeic dermatitis on head

© Amras666, via Wikimedia Commons

Seborrhoeic dermatitis on face

© Roymishali, CC BY-SA 3.0, via Wikimedia Commons

The areas of the body that tend to be affected are those where there are the most skin glands which make the oil (sebum). Therefore, the seborrhoeic dermatitis mainly affects the more greasy areas of the skin such as the:

• Scalp.

• Forehead.

• Face (particularly around the eyebrow area and on either side of the nose).

• Chest.

• Armpits.

• Groins.

• The area behind the ears, and just inside the ears.

In mild cases of seborrhoeic dermatitis

- flakes of skin cells or bad dandruff may be all that occurs. Dandruff is scaling of the scalp that happens as a result of seborrhoeic dermatitis. The scalp may also become itchy. Mild patches of flaky skin may also develop on the face.

If seborrhoeic dermatitis becomes worse - a rash also develops. The rash looks like round or oval patches of red, scaly, greasy skin. Each patch is commonly a few centimetres across but patches usually vary in size. Yellow-brown crusts may form on the top of each patch.

Several patches may develop in a few different areas of skin. The rash may be itchy and feel slightly raised as if it is on top of the skin. The scalp may also become itchy and/or sore. Some people also develop inflammation of the outer ear canal and/or of the eyelids.

Severe cases of seborrhoeic dermatitis - are unusual. If seborrhoeic dermatitis becomes severe then a red rash can affect much of the face, scalp, neck, armpits, chest and groins. People who have immune system problems such as untreated HIV, or an immune system which is suppressed due to medication are more prone to develop severe seborrhoeic dermatitis.

The exact cause of seborrhoeic dermatitis is not known. It is thought that yeast germs from the Malassezia species may be involved. However, it is not just a simple skin infection and you cannot catch this condition from others (it is not contagious). The germs live in the sebum of human skin in most adults. In most people they do no harm. But some people may react to these yeast germs, making the skin become inflamed.

People who have immune system problems, such as فيروس نقص المناعة البشرية والإيدز and people with مرض باركنسون, are more likely to develop seborrhoeic dermatitis. Also, emotional stress is thought to aggravate the condition. ملاحظة: a lack of cleanliness does not cause seborrhoeic dermatitis.

In most cases, no investigations are needed and seborrhoeic dermatitis is diagnosed by the typical symptoms and rash.

Commonly used treatments include the following:

• An anti-yeast (antifungal) shampoo such as كيتوكونازول is used to treat the scalp, eyebrows and other hairy areas. This kills the fungal germ and the skin then usually returns to normal. Use the shampoo 2-3 times a week (and use normal shampoo the rest of the time). Leave the shampoo on for about five minutes before rinsing off. Follow the instructions that come with the shampoo. Selenium sulfide has been used for this in the past, but has been unavailable in the UK for some years.

• An كريم مضاد للفطريات can be used to treat other areas. Apply the cream to affected areas once or twice daily, depending on the type of cream prescribed.

It often takes 2-4 weeks to clear the dandruff or rash completely. Keep using the treatment for a few days after the dandruff or rash has cleared. You should avoid using soap or shaving creams on your face, as they can add to the skin irritation. A non-greasy emollient soap substitute can be used. Cosmetic products that contain alcohol should also be avoided.

Other treatments which may be used include the following. The first three in the list are available either over the counter or from your GP, and the last three would usually be given after consultation with a specialist:

• A normal anti-dandruff shampoo that contains zinc pyrithione or coal tar may clear dandruff in mild cases, if used regularly. (The shampoo 'head & shoulders®' is an example.) If your dandruff is mild, with no itch, then you will probably be asked to buy shampoo over the counter rather than having it prescribed.

• A scale softener is sometimes advised for the scalp to lift the scale if dandruff is severe. This is in addition to the antifungal shampoo - it may contain salicylic acid.

• A mild steroid cream and/or steroid scalp lotion are sometimes advised each day for a week or so in addition to an antifungal cream or shampoo. This is used if the skin or scalp is badly inflamed. كريمات الستيرويد and lotions dampen inflammation, which reduces the redness and itch. However, you should not use steroid creams, ointments or lotions long-term. See your doctor if the inflammation does not settle within a week or so.

• Pimecrolimus cream أو مرهم تاكروليموس (topical calcineurin inhibitors) may sometimes be prescribed if skin inflammation is more severe.

• A course of antifungal tablets may be needed if the condition affects many areas of skin, or is not clearing with an antifungal cream.

• Light treatment (phototherapy) with ultraviolet B is sometimes used in severe cases.

The condition usually goes if the fungal germ is cleared from the skin by the above treatments. However, the oil (sebum) is a natural place for the germ to live. In many cases, the numbers of germs on the skin gradually rise again after finishing a course of treatment.

So, often, seborrhoeic dermatitis comes back (recurs) some weeks or months after a course of treatment has finished. Each episode can be treated as it occurs. However, if you have frequent episodes, you may wish to consider using treatment to prevent the condition from recurring.

Once the symptoms have gone with treatment, the following may help to keep the condition from recurring:

• For the scalp - use an anti-yeast (antifungal) shampoo such as ketoconazole once every 1-2 weeks. Leave on the scalp for five minutes before rinsing. Follow the instructions on the bottle and use a normal shampoo at other times. Coconut oil can also be used to moisturise your scalp and hair as it is easily absorbed.

• For the body - daily washing with soap and water helps to remove the greasy sebum from the body. This helps to keep the number of fungal germs to a minimum. Doing this, combined with using an antifungal shampoo every 1-2 weeks, and rubbing the shampoo lather on your body as well as your scalp, may keep the condition away. However, to keep the condition from recurring, some people need to use an antifungal cream 1-2 times a week, or every other week, on areas of the skin usually affected. You can discuss with your doctor the best preventative treatment for you.