Low dose of acyclovir may be an effective treatment against pityriasis rosea: a random investigator-blind clinical trial on 64 patients.

BACKGROUND: Pityriasis rosea (PR) is a papulosquamous disease with an unknown aetiology, but recently the role of two herpes viruses human herpes virus 6 and human herpes virus 7 was defined as being the aetiology of PR. OBJECTIVE: The aim of this study was to compare a low dose (400 mg five times a day for a week) anti-viral agent, acyclovir, with follow-up protocol for the treatment of PR. METHODS: A randomized, investigator-blind, prospective, 4-week study was designed. Sixty-four patients with PR presenting at the outpatient clinic were randomly allocated to acyclovir (400 mg five times a day for 1 week) or follow-up group. Fifty-four of them completed the period of study and their clinical responses such as improvement rate of erythema, and scaling and occurrence of complications were evaluated by two dermatologists using weekly photographic records. RESULTS: Statistically, acyclovir was more effective than follow-up in reducing erythema at the end of the first, second, third and fourth week of treatment. Although the decrease in scaling was higher in the acyclovir group at the end of the first, second and third week of treatment, there was no statistical significance between two groups at the end of fourth week of treatment in the both groups. CONCLUSIONS: According to our study, acyclovir may be more effective than follow-up in reducing erythema and shortening of duration of PR even in lower doses than was applied in previous studies. So given the safety of acyclovir, we suggest to our colleagues to consider this treatment when facing a patient suffering from this conundrum, at least in extensive or having pruritus ones.