Tinea versicolor (pityriasis versicolor): causes, symptoms and treatment

Pityriasis versicolor is the medical name for the condition many people search for as tinea versicolor. The NHS says it is a common fungal skin infection and that it is sometimes also called tinea versicolor. It is different from pityriasis rosea, which is a separate rash.

The British Association of Dermatologists (BAD) explains the name: pityriasis means a type of fine skin scaling and versicolor means changing colour. It describes a common and harmless rash that results from an overgrowth of the yeasts that live on everyone’s skin. These yeasts, called Malassezia, are not related to the yeast in food or to the yeasts that cause thrush.

In other words, the organism is already there. The NHS says most people have this fungus on their skin without any problem, and that sometimes it grows and spreads more than usual, though it is not always clear why.

The NHS says the condition causes patches of skin to change colour. The patches are flat and round, can join together to form large areas, may feel scaly and can sometimes be itchy. They usually appear on the chest, upper back, upper arms, neck or tummy.

The colour depends on skin tone. On white skin the NHS says the patches are usually pink, red or pale brown, and they may not tan in the sun. On brown or black skin the patches tend to be paler than the surrounding skin. BAD adds that sunlight causes the yeasts to make chemicals that prevent tanning, which is why the rash is often noticed for the first time after a sunny holiday.

BAD says the rash can be mildly itchy but usually causes no trouble apart from its appearance, and that it often goes unnoticed if only a few patches are present.

BAD says the overgrowth happens most often in warm, moist climates. Most people with the condition are in good health, it is most common in people in their early twenties, and people who get it may also have dandruff, which is caused by a similar yeast overgrowth on the scalp. BAD also says it is not hereditary and that it is not understood why some people tend to get it and others do not.

The NHS stresses that it is not caused by poor hygiene and that most people who have it are otherwise healthy. There is no evidence that it is related to yeast in the diet, according to BAD, so there is no need to change what you eat.

BAD says the diagnosis is usually made by a doctor looking at the rash. A special ultraviolet lamp known as a Wood’s lamp can be used to look for the yellow fluorescence typical of the condition, skin scrapings may sometimes be taken to confirm the diagnosis, and very occasionally a small skin biopsy may be considered if there is doubt.

The NHS warns against diagnosing it yourself because other conditions can look similar. Discoloured patches could be vitiligo, and flaky, raised patches could be psoriasis. It advises seeing a GP if patches of skin have changed colour, since pityriasis versicolor will usually only go away if treated, or if you have any other skin changes that worry you.

The NHS says a pharmacist or GP can advise on antifungal medicines. The main treatments are an antifungal shampoo such as ketoconazole used on the affected skin and rinsed off after 10 to 15 minutes, or an antifungal cream. If it covers a large area, or shampoos and creams do not work, a GP may prescribe antifungal tablets.

BAD lists the creams terbinafine, clotrimazole and miconazole, and says ketoconazole and selenium sulphide shampoos can be used as body washes left on the skin for up to 15 minutes. Tablets such as itraconazole and fluconazole are effective but can have side effects, so they are usually kept for widespread rashes or when topical treatment has failed.

The pale or altered areas take time to catch up. BAD says the rash clears with treatment although the pale areas will take several months to return to their normal colour, and that this does not mean treatment has failed. The NHS says the colour can take a few months to return.

BAD says the rash often recurs because the yeasts live on normal skin and cannot be completely eradicated. The NHS says that if the patches come back you may need the same treatment again, or your GP may suggest long-term treatment such as using an antifungal shampoo every few weeks.

BAD suggests that occasional use of an anti-dandruff shampoo as a short-contact body wash may reduce the chance of it returning, and that washing the upper body with an anti-dandruff shampoo for a few weeks before a sunny holiday, or a trip to a humid area, may help reduce the level of skin yeasts. It adds that the condition does not leave scars.

For most people the main issue is cosmetic. Patches are more noticeable after sun exposure because the surrounding skin tans and the affected skin does not, which can feel distressing even though the condition is harmless.

NHS pharmacists can often advise on treatment without an appointment, and a GP is the next step if treatment has not worked or the diagnosis is uncertain. Private dermatology consultations are available but are rarely needed for a straightforward case; they are more relevant when the rash is extensive, repeatedly returns, or looks atypical.