Aciclovir and famciclovir for preventing postherpetic neuralgia

Ilona Mikkola and Annamari Ranki

Level of evidence: B

Oral aciclovir or famciclovir do not appear to significantly reduce the incidence of postherpetic neuralgia in immunocompetent patients.

A Cochrane review in 2014 «Chen N, Li Q, Yang J ym. Antiviral treatment for p...»1 included six randomized controlled trials with a total of 1211 immunocompetent participants of all ages with herpes zoster, of all degrees of severity, within 72 hours after the onset. More than 831 (69 %) participants were 50 years of age or older. Five trials evaluated oral aciclovir compared with placebo or no treatment, and one, with 419 participants, evaluated oral famciclovir versus placebo for preventing postherpetic neuralgia (PHN), which was the main outcome.

For primary outcome, based on three trials (609 participants) the Cochrane review found no significant difference between the aciclovir and control groups in the incidence of PHN four months after the onset of the acute herpetic rash (risk ratio (RR) 0.75, 95 % confidence interval (CI) 0.51 to 1.11, I2=0,19), nor was there a significant difference at six months (RR 1.05, 95 %CI 0.87 to 1.27, two trials, 476 participants, I2=0,16). In four of the trials (692 participants), there was some evidence for a reduction in the incidence of pain four weeks after the onset of rash. In the trial of famciclovir versus placebo, neither 500 mg nor 750 mg doses of famciclovir reduced the incidence of herpetic neuralgia significantly.

  • Study quality: High
  • Applicability: Good
  • Comment: The quality of evidence is downgraded by original trial's unclear risk of bias. There were no subgroup analyze performed among the oldest age group (i.e. 75+ years).


  1. Chen N, Li Q, Yang J ym. Antiviral treatment for preventing postherpetic neuralgia. Cochrane Database Syst Rev 2014;:CD006866 «PMID: 24500927»PubMed