Shaoyao Gancao decoction for neuropathic pain: a systematic review and meta-analysis of postherpetic neuralgia.

Abstract

Objective: To systematically evaluate the efficacy and safety of Shaoyao Gancao Decoction (SGD) for neuropathic pain (NP), with a focused analysis on postherpetic neuralgia (PHN), the most evidence-rich subtype, and to provide evidence for clinical decision-making.

Methods: Randomized controlled trials (RCTs) on SGD for PHN were retrieved from databases up to March 2026. Two reviewers independently screened literature, extracted data, and assessed risk of bias using the Cochrane tool. Meta-analyses were performed using RevMan 5.3, and effect sizes were expressed as odds ratio (OR) or mean difference (MD) with 95% confidence intervals (CIs).

Results: Fifteen RCTs involving 1,188 patients with PHN (594 per group) were included. Compared with conventional Western medicine alone, the addition of SGD significantly improved the overall response rate (OR=5.42, 95% CI: 3.40-8.64, P<0.0001), reduced Visual Analogue Scale (VAS) pain score (MD=-1.33, 95% CI: -1.68 to -0.99, P<0.0001), improved Pittsburgh Sleep Quality Index (PSQI) score (MD=-2.23, 95% CI: -2.85 to -1.62, P<0.0001), and lowered the incidence of adverse events (OR=0.34, 95% CI: 0.21-0.56, P<0.0001). Subgroup analyses by treatment duration (14 and 28 days) showed consistent analgesic effects and overall efficacy. Pain Rating Index (PRI) and Present Pain Intensity (PPI) scores were also significantly improved in the SGD group (both P<0.0001). Although high heterogeneity was observed in VAS (I²=97%), subgroup and sensitivity analyses suggested that the pooled results remained robust. Given that PHN represents a common NP subtype, SGD may have potential therapeutic value for broader NP conditions.

Conclusion: Current evidence supports SGD as an adjunctive therapy for PHN, with good efficacy and safety. Its potential value for other NP types (such as diabetic peripheral neuropathy, chemotherapy-induced neuropathy) warrants further research.