What is pityriasis Versicolor?
Pityriasis means a type of fine skin scaling, and Versicolor means changing color. 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 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,’ live on the surface of everyone’s skin. Some of them are yeasts. At times, these yeasts can overgrow and trigger the rash known as pityriasis Versicolor. This condition happens most often in warm moist climates. Most people with this condition are in good health.
The rash has a mixture of colors– hence the name ‘Versicolor.’ It looks pale brown or pink on untanned, white skin, but sunlight will cause the yeasts to make chemicals that prevent tanning, so the rash stays paler than the surrounding skin. The rash is often seen after exposure to the sun, like on a sunny holiday.
The condition is most common in people in their early 20s. People who get it may also have dandruff caused by a similar yeast overgrowth on the scalp. We do not understand why some people tend to get it, and others do not.
Is it hereditary?
No.
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.
How does it look like?
The rash usually affects the torso but can also affect the upper arms, neck, and stomach. Flat, slightly scaly areas of altered color appear more evident against a background of unaffected skin. The color of the patches may vary from pale to dark brown. On white skin, the affected areas usually appear darker than surrounding skin, and in dark-skinned people, the affected patches can appear pale.
How will it be diagnosed? The diagnosis is usually made by your doctor looking at the rash. A special ultra-violet lamp, known as Wood’s lamp, can be used to look for yellow fluorescence typical of pityriasis Versicolor. Sometimes your doctor may take skin scrapings to confirm the diagnosis.
Can it be cured?
Yes, the rash clears with treatment, although the pale areas will take several months to return to their normal color. Importantly, this does not mean that treatment has failed. The rash often recurs as the yeasts that cause it to live on normal skin and cannot be eradicated entirely. Pityriasis Versicolor does not leave scars.
How can it be treated?
Treatment includes antifungals in the form of cream and tablets.
What can I do?
It may help if you wash with an anti-dandruff shampoo for a few weeks before you go on a sunny holiday to reduce the level of skin yeasts. There is no evidence that the complaint is related to yeast in food, so there is no need to change your diet.