What is pityriasis versicolor?
Pityriasis versicolor, also known as tinea versicolor, is a fungal skin infection that causes small patches of skin to become discoloured. Malassezia yeast, the family of yeast that causes pityriasis versicolor, is found on the skin of most adults only becoming problematic when it begins to grow faster than usual.
What are the symptoms of pityriasis versicolor?
The discolouration caused by pityriasis versicolor can make skin lighter or darker than its normal colour (referred to as hypo- or hyper-pigmentation). Patches are usually pink to brown or red in colour with a fine scaly surface and do not tan. In some cases, the patches can become itchy. The patches are most often seen on the chest, abdomen, back and upper arms.
Pityriasis versicolor is not contagious and cannot be passed on from one person to another.
What causes pityriasis versicolor?
Pityriasis versicolor occurs when the normal balance of micro-organisms on the skin is disturbed. This imbalance can be caused by hyperhidrosis (excessive sweating), which encourages growth of the Malassezia yeast. For this reason, infection is more common over the summer months and in humid climates. Other triggers include malnutrition, a weakened immune system and treatment with corticosteroids.
People in their teens or early 20s and those with oily skin have a higher chance of developing pityriasis versicolor.
Although pityriasis versicolor is not contagious, people in the same family are more likely to suffer from it, suggesting that some people are genetically more prone to the infection.
Are there any tests necessary?
Pityriasis versicolor can usually be diagnosed by a GP or pharmacist examining the affected skin. Examination using a special UV light, known as a Wood's light, may help with diagnosis in some cases. Swabs may be taken and microscopy can also be used, although these tests are rarely necessary.
What treatment is available?
Pityriasis versicolor is usually treated with an antifungal shampoo containing ketoconazole (eg, Nizoral®) or selenium sulfide (Selsun®). These shampoos are applied to the skin and left for five to 10 minutes before being rinsed off. They should be used once daily for five to seven days. Antifungal creams such as clotrimazole (eg, Canesten®) and miconazole (Daktarin®) can also be used to treat small areas and should be continued for two to three weeks.
If these topical antifungals do not work or if large parts of the body are affected, pityriasis versicolor can be treated with antifungal capsules. These usually need to be taken for at least a week and sometimes for up to a month and may have more side effects than using creams and shampoos.
The condition will usually resolve within two to three months of starting antifungal treatment. However, recurrence is common, particularly in summer.
For people who are prone to developing pityriasis versicolor when they are exposed to warm humid environments or sun, treatment with ketoconazole shampoo for up to three days beforehand may prevent its recurrence. If episodes are frequent or severe referral to a dermatologist will be required.
Fact sheet provided by MIMS
Date last reviewed: April 2015