Background: Idiopathic sudden sensorineural hearing loss has great impact on quality of life. Many clinical trials using Chinese herbal medicine for idiopathic sudden sensorineural hearing loss have been conducted and reported beneficial results. However, there is no critical appraised evidence on efficacy and safety of Chinese herbal medicine for idiopathic sudden sensorineural hearing loss to inform clinical use.

Objective of review: To assess the beneficial effect and safety of Chinese herbal medicine for idiopathic sudden sensorineural hearing loss.

Type of review: Systematic review of randomised clinical trials.

Search strategy: Seven electronic databases and two trial registries were searched for all eligible trials from inception to January 2013.

Evaluation method: Two authors independently selected trials and extracted data. The Cochrane risk of bias tool was utilised to assess the methodological quality of the included trials. revman 5.2 software was applied for data analysis with effect estimate presented as risk ratio and mean difference with its 95% confidence interval.

Results: Forty-one randomised clinical trials involving 3560 participants were identified. Five kinds of Chinese herbal medicine were trialed. All trials compared conventional therapies of steroids, vasodilators, anticoagulants, nutritional supplements or hyperbaric oxygen with or without herbal medicine. No trial was identified that compared herbal medicine alone with placebo. No trial was identified that blinded the participants or the observers to their herbal medication. Only one trial adequately reported its method of randomisation. No trial reported the sample size calculated to show an effect. All trials had material other defects giving a high likelihood of bias. Because of the overall poor quality of all 41 trials, it was concluded that there was no level-one evidence to support the use of Chinese herbal medicine, alone or in addition to conventional therapies, to improve the hearing in adults with idiopathic sudden sensorineural hearing loss. Two trials reported adverse effects, and no severe adverse effects were found in the Chinese herbal medicine groups.

Conclusions: The existing evidence for the beneficial effect and safety of Chinese herbal medicine for idiopathic sudden sensorineural hearing loss comes from methodologically poor studies and therefore cannot be reliably used to support their clinical use. We identify a justification to further investigate the effect and safety of Chinese herbal medicine for people with idiopathic sudden sensorineural hearing loss in rigorously designed randomised trials.