Background: Herpes zoster is a common affliction in older patients, with up to 15% experiencing some residual pain in the distribution of the rash several months after healing. Despite numerous randomized clinical trials, the effect of treating herpes zoster with oral acyclovir in preventing postherpetic neuralgia remains uncertain because of conflicting results.
Methods: Meta-analysis of published randomized clinical trials on the use of acyclovir to prevent postherpetic neuralgia using the fixed-effects model of Peto.
Results: Thirty clinical trials of treatment with oral acyclovir in immunocompetent adults were identified. After excluding studies with duplicate data, suboptimal and topical dosing, non-placebo-controlled or nonrandomized designs, and those using intravenous acyclovir, 5 trials were found to be homogeneous and were combined for analysis. From these trials, the summary odds ratio for the incidence of "any pain" in the distribution of rash at 6 months in adults treated with acyclovir was 0.54 (95% confidence interval, 0.36-0.81).
Conclusion: Treatment of herpes zoster with 800 mg/d of oral acyclovir within 72 hours of rash onset may reduce the incidence of residual pain at 6 months by 46% in immunocompetent adults.