Interventions for pityriasis rosea

Pityriasis rosea is a scaly rash that mainly affects young adults. It can be very itchy but most people recover within 2 to 12 weeks.

To assess the effects of interventions for pityriasis rosea.

We searched the Cochrane Skin Group Specialised Register (December 2004), the Cochrane Central Register of Controlled Clinical Trials in The Cochrane Library (Issue 4, 2004), MEDLINE (1966 to January 2005), EMBASE (1976 to January 2005), LILACS (1982 to January 2005), BIOSIS Preview (1980 to June 2002), and ongoing trials databases. We scanned bibliographies of published studies, abstracts from dermatology conference proceedings, corresponded with trialists and contacted the pharmaceutical industry.

Randomised controlled trials evaluating interventions for pityriasis rosea.

Two authors independently assessed trial quality and extracted data. We contacted study authors to retrieve missing data.

Three trials involving 148 people were included. One poor quality trial (23 people), compared intravenous glycyrrhizin and intravenous procaine. It found no significant difference between the two interventions for treating symptoms and rash. One fair quality trial (85 people), compared the oral antihistamine dexchlorpheniramine (4 mg), the oral steroid betamethasone (500 mcg), and a combination of betamethasone (250 mcg) and dexchlorpheniramine (2 mg). It found no significant difference in itch resolution at two weeks, as rated by the participants, between dexchlorpheniramine and betamethasone, and the combination of dexchlorpheniramine and betamethasone. However, both dexchlorpheniramine and betamethasone alone seem to be better at clearing rash than the combination of dexchlorpheniramine and betamethasone. These interventions were not compared with placebo. The small good quality trial (40 people) that compared oral erythromycin and placebo found that erythromycin was more effective than placebo in terms of rash improvement, as rated by the trialists, after two weeks (RR 13.00; 95% CI 1.91 to 88.64). It was also more effective in decreasing the itch score (difference of 3.95 points, 95% CI 3.37 to 4.53). No serious adverse effects were reported for the interventions. Two out of 17 people on oral erythromycin and 1 out of 17 on placebo reported minor gastrointestinal upset.

We found inadequate evidence for efficacy for most treatments for pityriasis rosea. Oral erythromycin may be effective in treating the rash and decreasing the itch. However, this result should be treated with caution since it comes from only one small RCT. More research is necessary to evaluate the efficacy of erythromycin and other treatments.