Seborrhoeic dermatitis causes bad dandruff and sometimes a rash,
commonly on the face and upper body. An antifungal shampoo and/or an
antifungal cream will usually clear the dandruff and rash. The
condition tends to recur. If it recurs frequently, regular use of an
antifungal shampoo and/or cream will usually keep it away.
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.
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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.
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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.
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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.
What is the treatment for seborrhoeic dermatitis?
Commonly used treatments include the following:
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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.
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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:
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A 'normal' anti-dandruff shampoo that contains zinc pyrithione or coal tar may clear dandruff in mild cases, if used regularly.
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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.
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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.
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A course of antifungal tablets may be needed if the condition affects many areas of skin, or is not clearing with an antifungal cream.
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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.
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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.)
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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.
Disclaimer: This article is for information only and should not
be used for the diagnosis or treatment of medical conditions. EMIS and
PiP have used all reasonable care in compiling the information but make
no warranty as to its accuracy. Consult a doctor or other health care
professional for diagnosis and treatment of medical conditions.
© EMIS and PiP 2008 Reviewed: 23 Aug 2008
