Seborrhoeic Dermatitis of Adults

What is seborrhoeic dermatitis and who gets it?

Seborrhoeic dermatitis is a type of skin inflammation. It is sometimes called seborrhoeic eczema. It mainly occurs in young adults and teenagers. About 1 in 25 adults develop this condition. It is more common in men than women. Some babies have a similar condition that usually clears within a few months which is sometimes called 'cradle cap'. (See separate leaflet called 'Seborrhoeic Dermatitis in Babies'.) It does not usually occur in children older than about 8-9 months.

The exact cause is not known. A type of fungal germ called Malassezia furfur (previously called Pityrosporum ovale) is thought to be involved. However, it is not just a simple skin infection and it is not contagious (you cannot 'catch' this condition from others). The germ lives in the sebum (oil) of human skin in most adults. In most people it does no harm. But some people may 'react' to this yeast germ in some way which causes inflammation.

What are the symptoms of seborrhoeic dermatitis?

The areas of the body that tend to be affected are those where there are the most skin glands which make the sebum. Therefore, the condition mainly affects the more 'greasy' areas of the skin such as the scalp, the forehead and the face. Other areas which are sometimes affected are the chest, the armpits, under the breasts, and the groins.

• In mild cases bad dandruff may be all that occurs. The scalp may also become itchy. Also, mild patches of flaky skin may develop on the face.
• If the condition 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 they vary in size. Yellow-brown crusts may form on the top of each patch. Several patches may develop which appear in a few 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 are unusual. If it becomes severe then a red rash can affect much of the face, scalp, neck, armpits, chest and groins. People with HIV/AIDS are more prone to develop severe seborrhoeic dermatitis.

The condition tends to flare up and down from time to time. However, treatment can usually keep symptoms to a minimum. For a list of websites that contain pictures of skin conditions including seborrhoeic dermatitis see www.patient.co.uk/showdoc/1097/

What is the treatment for seborrhoeic dermatitis?

Commonly used treatments include the following:

• An antifungal (anti-yeast) shampoo such as ketoconazole 2% 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.
• An antifungal cream is 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 completely clear the dandruff or rash. Keep using the treatment for a few days after the dandruff or rash have cleared.

Other treatments which may be used include the following:

• A 'normal' anti-dandruff shampoo that contains zinc pyrithione or coal tar may clear dandruff in mild cases, if used regularly.
• 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.
• A mild steroid cream and/or steroid scalp lotion is 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. Steroid creams 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.
• A course of antifungal tablets may be needed if the condition affects many areas of skin, or is not clearing with an antifungal cream.
• Phototherapy (light treatment) with ultraviolet B is sometimes used in severe cases.

The condition goes if the fungal germ is cleared from the skin by the above treatments. However, the sebum is a natural place for the germ to live. In many cases, the number of germs gradually rise again on the skin after finishing a course of treatment. So, in many cases the condition tends to recur some weeks or months after finishing a course of treatment. 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.

How can I prevent seborrhoeic dermatitis from recurring?

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

• For the scalp - use an antifungal shampoo such as ketoconazole 2% once every 1-2 weeks. Leave on the scalp for five minutes before rinsing. (Use a normal shampoo at other times.)
• 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 1-3 times a week on areas of the skin usually affected.