What are the aims of this leaflet?
This leaflet has been written to help you understand more about pityriasis versicolor. 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 pityriasis versicolor?
Pityriasis means a type of fine skin scaling, and versicolor means changing colour. It is a common and harmless rash due to the overgrowth of yeasts that live on everyone’s skin. These yeasts, called Malassezia, are not related to yeast in food or to those that cause thrush. It is also sometimes called tinea versicolor.
What causes it?
Large numbers of tiny harmless organisms, known as ‘the resident flora’, are present on the surface of everyone’s skin. They live there, doing no harm. Some of them are yeasts. At times, these yeasts can increase in number and cause the rash known as pityriasis versicolor. This happens most often in warm moist climates. Most people with this condition are perfectly well and healthy.
Once the rash appears its main feature is the way it varies in colour – hence the name versicolor. It looks pale brown or pinkon an untanned white skin; however sunlight causes the yeasts to make chemicals that upset the pigment cells (melanocytes) in the skin. As a result the rash fails to tan and so stays paler than the surrounding skin. For this reason the rash is often noticed for the first time after a sunny holiday.
The condition is most common in people in their early 20s. You cannot catch it because we all have the same yeasts on our skin, even if we do not have the rash of pityriasis versicolor. We do not know why some people tend to get it and others do not.
Is it hereditary?
What are its symptoms?
The rash can be mildly itchy but usually causes no trouble apart from its appearance. It often goes unnoticed if only a few patches are present.
What does it look like?
The rash is usually on the trunk. Flat, slightly scaly areas of altered colour show up against a background of normal skin. The colour of the patches ranges from being darker than the surrounding skin (reddish-fawn or brown) in areas that have never seen the sun, to areas that have become pale or white after being in the sun. The darker the skin, the easier it is to see these pale areas.
How will it be diagnosed?
Usually the diagnosis is easy for your doctor to make just by looking at the rash. A dermatologist may shine a special ultra-violet light lamp known as Wood’s lamp on the skin to check for the typical yellow fluorescence of pityriasis versicolor. If there is any doubt, skin scrapings can be looked at under the microscope to see if yeasts are present. Sometimes a skin test (biopsy) is necessary.
Can it be cured?
Yes, the rash clears with treatment though the pale areas will take a few months to get back to their normal colour. Pityriasis versicolor does not leave scars. Often the rash does come back, mainly in the summer, as the yeasts that cause it live on normal skin and never go away completely.
How can it be treated?
Treatments applied to the skin:
Most patients are treated only with applications to the skin. Treatments that reduce the amount of the yeasts include ketoconazole and selenium sulphide shampoos. These are often used as a body wash. How you use them will depend on which type your doctor recommends.
Medicines taken by mouth:
These include itraconazole and fluconazole. They work well but are usually kept in reserve for widespread rashes, or those that have not got better with treatment put on the skin.
The rash of pityriasis versicolor often comes back. Using a medicated shampoo as a bodywash to the trunk from time to time, over several months, cuts down this risk. If the area affected is small, ketoconazole or clotrimazole cream can be applied twice daily. Remember that the pale areas left after treatment may take several months to get back to their normal colour. This cannot be speeded up.
What can I do?
If you tend to suffer from pityriasis versicolor, and are going on holiday to the sun, you might want to try using an anti-yeast shampoo as a body wash on your skin for a few weeks before you go. Changing your diet will not help.
Where can I get more information about it?
Web links to detailed leaflets: