Pityriasis rosea is a common skin disease in which round or oval, scaling pink patches develop mainly on the trunk, upper arms, and thighs. In many cases, the eruption begins with a single scaling patch (commonly called the “herald patch”), followed 1-2 weeks later by development of a widespread rash. The herald patch resembles ringworm, and thus can be mistakenly diagnosed. Pityriasis rosea most commonly occurs in older children and teenagers, but can appear at any age. It often occurs in seasonal epidemics during spring and fall, but may develop as an isolated case at any time.
The cause of pityriasis rosea is unknown. Because of its tendency to occur in seasonal epidemics, and because of its rather predictable course, it is thought to be a response to a virus. The rash itself is not contagious.
Pityriasis rosea lasts from 6-12 weeks, and then resolves leaving no scars. Since many patients are first seen in the early stage of their disease, their condition may appear to worsen considerably before it begins to improve. Typically, the eruption will peak in about 2 weeks, and slowly diminish over the following month. Usually the face, forearms, and hands are not heavily involved, though there are exceptions. In most persons, the condition is not particularly uncomfortable or inconvenient.
You should contact your doctor if your condition becomes much worse, or if it does not seem to follow the pattern described above.
No limitation of activities is required. You do not need to stay home.
Treatment is for relief of symptoms only, and does not alter the overall course of the disease. Sometimes the rash is itchy. In that case, a prescription anti-itch cream or lotion may be applied to the uncomfortable areas.
Scrubbing the affected areas with soap or a washcloth, or the use of very hot water for bathing or showering will generally worsen the itching of pityriasis rosea.
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