Pityriasis rosea may be caused by a viral infection.
The most common symptoms are itching and an initial large, tan-colored or rose-colored circular patch that is followed by multiple patches that appear on the torso.
The diagnosis is based on symptoms.
This disease usually resolves with no treatment, and itching that is not severe may be alleviated with artificial or natural sunlight.
The cause of pityriasis rosea is not certain, but an infection with human herpesvirus type 6, 7, or 8 may be involved. However, the disorder is not thought to be contagious. Pityriasis rosea most commonly occurs in people between the ages of 10 and 35 years. Pityriasis rosea affects women more often than men.
Pityriasis rosea causes a rose-colored or tan-colored patch of skin about 1 to 4 inches (2 to 10 centimeters) in diameter that doctors call a herald or mother patch. The rose or tan color is not as obvious in people with darker skin. This round or oval area usually develops on the torso. Sometimes the patch appears without any previous symptoms, but some people have a vague feeling of illness, loss of appetite, fever, headache, and sometimes joint pain a few days before the patch appears.
In 7 to 14 days, many similar but smaller patches appear on other parts of the body. These secondary patches are most common on the torso, especially along and radiating from the spine. In children, the patches commonly begin in the groin or underarms and spread outward. Children and pregnant women may have little or no scaling. Most people with pityriasis rosea have some itching, and in some people the itching can be severe.
Both artificial and natural sunlight may speed clearing and relieve the itching.
Other standard treatments for itching may be used as needed (see treatment of itching). Corticosteroids applied directly to the skin (topically) can also be used for short periods to help relieve itching.
Corticosteroids taken by mouth are necessary only for very severe itching.
Pregnant women with pityriasis rosea should be offered a prescription for acyclovir, an antiviral drug. However, treatment with an antiviral drug may not reduce the risk of premature birth or stillbirth.