A randomized trial of acyclovir for 7 days or 21 days with and without prednisolone for treatment of acute herpes zoster.

BACKGROUND: Acyclovir given for 7 to 10 days is of proved benefit in acute herpes zoster, but studies of its effectiveness in preventing postherpetic neuralgia have had conflicting results. The role of corticosteroids in the treatment of herpes zoster is also controversial.

METHODS: We conducted a double-blind, controlled trial in patients with acute herpes zoster to determine whether either 21 days of acyclovir therapy or the addition of prednisolone offered any improvement over 7 days of acyclovir therapy. Patients with a rash of less than 72 hours' duration were assigned to receive acyclovir (800 mg orally, five times daily) for 7 days with either prednisolone or placebo, or acyclovir for 21 days with either prednisolone or placebo. Prednisolone therapy was initiated at a dose of 40 mg per day and tapered over a three-week period. Patients were assessed frequently through day 28 and then monthly through month 6 to assess postherpetic neuralgia.

RESULTS: Of 400 patients recruited, 349 completed the study. No significant differences were detected between the four groups in the progression of the rash (P > 0.1). With steroid therapy, a significantly higher proportion of the rash area had healed on days 7 and 14 (P = 0.02). Pain reduction was greater during the acute phase of disease in patients treated with steroids or 21 days of acyclovir (P < 0.01 and P = 0.02, respectively, on day 7; P < 0.01 for steroid therapy on day 14). However, on follow-up there were no significant differences between any of the groups in the time to a first or a complete cessation of pain. The steroid recipients reported more adverse events.

CONCLUSIONS: In acute herpes zoster, treatment with acyclovir for 21 days or the addition of prednisolone to acyclovir therapy confers only slight benefits over standard 7-day treatment with acyclovir. Neither additional treatment reduces the frequency of postherpetic neuralgia.