Vitamin B12 for herpetic neuralgia: A meta-analysis of randomised controlled trials

Background: Postherpetic neuralgia (PHN) is the most distressful complication of herpes zoster. PHN results in an impaired quality of life and higher healthcare utilization. Vitamin B12 has been proven to be effective in pain relief for various conditions. Objective: We conducted a systematic review and a meta-analysis to evaluate the efficacy of vitamin B12 supplementation in PHN patients. Methods: PubMed, Embase, Cochrane Library, CINAHL, and ClinicalTrials.gov registry were searched. Randomised control trials evaluating the efficacy and safety of vitamin B12 in PHN patients were selected. Eligible trials were abstracted and assessed for the risk of bias by two reviewers, and the results of pain indicators in the selected trials were analysed. Results: Four trials including 383 participants were published between 2013 and 2016. Compared with the placebo group, the Vitamin B12 group exhibited a significant decrease in the Numeric Rating Scale score, with a mean difference of - 4.01 (95% confidence interval = - 4.70 to - 3.33). Vitamin B12 administration improved the quality of life of PHN patients with moderate quality evidence and significantly decreased the number of patients using analgesics. Conclusion: Vitamin B12 appears to be an attractive complementary therapy for PHN patients. Further investigation is needed before conclusive recommendations can be made.