What causes pityriasis rosea?
The cause of pityriasis rosea, a disease described well over 100 years ago, still is unknown. Because it is most common in young adults, can occur in small groups of related individuals, does not recur, and bears a superficial resemblance to other childhood viral diseases, it is thought to have an infectious cause. Most of the time, aside from the skin eruption, the disease is asymptomatic and resolves after a course of about six to 12 weeks. So for most patients, it is important to distinguish this disease from other skin diseases which do require treatment and do not resolve on their own. The pattern of the rash, the course of the disease, a few blood tests, and occasionally a skin biopsy may be necessary to accomplish this.
How to treat pityriasis rosea
In those few patients in whom the itching is severe enough to require treatment, there are a number of alternatives. Mild to moderately potent topical steroids and oral antihistamines (many of which are available without a prescription) will suffice. Sometimes ultraviolet light administered in a doctor's office or by careful sunbathing can diminish the itching sufficiently to be tolerable. The administration of oral erythromycin (E-Mycin, Eryc, Ery-Tab, PCE, Pediazole, Ilosone) has been popular in the past to relieve symptoms, but the evidence to support its benefits is not particularly strong.
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Medically reviewed by Norman Levine, MD; American Board of Dermatology
Drago, F., and A. Rebora. "Treatments for Pityriasis Rosea." Skin Therapy Letter 14 (2009): 6-7.