IMPORTANCE: Sudden sensorineural hearing loss (SSNHL) is an otological emergency of unknown etiology. Recent reports showed that antioxidant drugs can benefit patients with SSNHL. This study attempted to evaluate the effect of adding antioxidant vitamins as an adjuvant therapy alongside with corticosteroids. OBJECTIVE: To evaluate the effects of the 3 major antioxidant vitamins (A, C, and E) as an adjuvant therapy, administered with corticosteroids, for the treatment of SSNHL in adult patients (≥18 years). DATA SOURCES: MEDLINE, EMBASE, PubMed, Web of Science and Cochrane electronic databases from January 1, 1995, through September 25, 2017. STUDY SELECTION: Published studies of adult patients who received antioxidant vitamins (A, C, E, or any combination of these vitamins) as an adjuvant therapy in addition to the regular treatment (corticosteroids) for SSNHL. Quality assessment was performed using the Cochrane Collaboration Tool for Assessing Risk of Bias. DATA EXTRACTION: Each study had a control group (conventional treatment + placebo) and a trial group (antioxidant vitamin(s) + conventional treatment). RESULTS: From 446 manuscripts identified in the literature, 3 studies were included in the review with 279 patients. The most common vitamins used to treat SSNHL were the 3 major antioxidant vitamins A, C, and E, combined sometimes with other antioxidants such as selenium. CONCLUSIONS AND RELEVANCE: The success of the treatment is increased in patients who received antioxidant vitamins in combination with conventional therapy.