Background Postherpetic neuralgia is a common, serious painful complication of herpes zoster. Corticosteroids are anti-inflammatory and might be beneficial. This is an update of a review first published in 2008 and previously updated in 2010. Objectives To examine the efficacy of corticosteroids in preventing postherpetic neuralgia. Search methods We updated the searches for randomised controlled trials (RCTs) of corticosteroids for preventing postherpetic neuralgia in the Cochrane Neuromuscular Disease Group Specialized Register (16 April 2012), CENTRAL (2012, Issue 3), MEDLINE (January 1966 to April 2012), EMBASE (January 1980 to April 2012), LILACS (January 1982 to April 2012), and the Chinese Biomedical Retrieval System (1978 to 2012). We also reviewed the bibliographies of identified trials, contacted authors and approached pharmaceutical companies to identify additional published or unpublished data. Selection criteria We included all RCTs involving corticosteroids given by oral, intramuscular, or intravenous routes for people of all ages with herpes zoster of all degrees of severity within seven days after onset, compared with no treatment or placebo but not with other treatments. We did not include quasi-RCTs (trials in which a systematic method of randomisation such as alternation or hospital number was used). Data collection and analysis Two authors identified potential articles, extracted data, and independently assessed the risk of bias of each trial. Disagreement was resolved by discussion among the co-authors. Main results Five trials were included with 787 participants in total. All were randomised, double-blind, placebo-controlled parallel-group studies. We conducted a meta-analysis of two trials (114 participants) and the results gave moderate quality evidence that oral corticosteroids did not prevent postherpetic neuralgia six months after the onset of herpes (RR 0.95, 95% CI 0.45 to 1.99). One of these trials was at high risk of bias because of incomplete outcome data, the other was at low risk of bias overall. The three other trials that fulfilled our inclusion criteria were not included in the meta-analysis because the outcomes were reported at less than one month or not in sufficient detail to add to the meta-analysis. These three trials were generally at low risk of bias. Adverse events during or within two weeks after stopping treatment were reported in all five included trials. There were no significant differences in serious or non-serious adverse events between the corticosteroid and placebo groups. There was also no significant difference between the treatment groups and placebo groups in other secondary outcome analyses and subgroup analyses. The review was first published in 2008 and no new RCTs were identified for inclusion in subsequent updates in 2010 and 2012. Authors' conclusions There is moderate quality evidence that corticosteroids given acutely during zoster infection are ineffective in preventing postherpetic neuralgia. In people with acute herpes zoster the risks of administration of corticosteroids do not appear to be greater than with placebo, based on moderate quality evidence. Corticosteroids have been recommended to relieve the zoster-associated pain in the acute phase of disease. If further research is designed to evaluate the efficacy of corticosteroids for herpes zoster, long-term follow-up should be included to observe their effect on the transition from acute pain to postherpetic neuralgia. Future trials should include measurements of function and quality of life.