Chinese herbal medicine for headache: A systematic review and meta-analysis of high-quality randomized controlled trials

Background: Chinese herbal medicines (CHMs) are widely used to relieve headache in Asia. However, it is uncertain whether there is robust evidence on the effects of CHMs for headache. Purpose: To assess the effectiveness and safety of CHMs for headache using systematic review of high-quality randomized controlled trials (RCTs). Methods: Electronic search was conducted on six databases from inception to January 2018. We included the RCTs that met the requirement of at least 4 out of the 7 domains according to the Cochrane risk of bias tool. Results: Thirty RCTs with 3447 subjects were ultimately included for analysis and all trials were conducted in Asia. Meta-analysis showed that CHMs monotherapy were superior to placebo in reducing headache frequency [SMD -0.48 (95% CI -0.76, -0.20); p< 0.01], headache days [SMD -0.29 (95% CI -0.45, -0.13); p< 0.01], headache duration[SMD -0.58 (95% CI -0.81, -0.36); p< 0.01], headache intensity [SMD -0.42 (95% CI -0.62, -0.23); p< 0.01] and analgesic consumption [SMD -0.36 (95% CI -0.52, -0.21); p< 0.01] and improving clinical efficacy rate (p< 0.01). Similarly, CHMs monotherapy were superior to western conventional medicines (WCMs) in headache frequency [SMD -0.57 (95% CI -0.84, -0.29); p< 0.01], headache days (p< 0.01), analgesic consumption [SMD -1.63 (95% CI -1.98, -1.28); p< 0.01], headache intensity [SMD -0.81 (95% CI -1.06, -0.57); p< 0.01], and clinical efficacy rate [RR 1.24 (95% CI 1.18, 1.31); p< 0.01], except reducing headache duration (p> 0.05). CHMs adjunct therapy can improve clinical efficacy rate compared with WCMs alone [RR 1.15 (95% CI 1.09, 1.22); p< 0.01]. Meanwhile, CHMs had fewer adverse events than that of controls. Conclusion: The findings supported, at least to an extent, the use of CHM for headache patients; however, we should treat the results cautiously because the clinical heterogeneity.