Intravaginal Vitamin C for the Treatment and Prevention of Bacterial Vaginosis: A Systematic Review and Meta-analysis.

OBJECTIVE: To evaluate the effectiveness of intravaginal vitamin C in the treatment and prevention of bacterial vaginosis compared with control or antibiotics. DATA SOURCES: Electronic databases (MEDLINE, EMBASE, Cumulated Index in Nursing and Allied Health Literature, and Cochrane Central Register of Controlled Trials), Google Scholar, clinical trial registries, and gray literature were searched for articles in any language from inception to May 2025. METHOD OF STUDY SELECTION: We included randomized trials involving nonpregnant patients and intravaginal vitamin C as treatment for acute bacterial vaginosis or prevention of recurrence. Covidence software was used for study screening. TABULATION, INTEGRATION, AND RESULTS: Risk of bias was assessed with the Cochrane Risk of Bias 2 tool. The primary outcome was clinical or microbiologic cure or recurrence. Results were reported as risk ratios (RRs) with 95% CIs. Certainty in conclusions was reported with the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach. Nine trials (n=1,107) were included. Eight evaluated primary treatment of bacterial vaginosis, with a maximum follow-up of 30 days. Most trials used a vitamin C dose of 250 mg daily for 6 days. Among these trials, four compared vitamin C with control (placebo or no treatment) and four with metronidazole. Only one trial, comparing vitamin C with placebo, assessed prevention of recurrence after antibiotic cure. We found a higher proportion of short-term cure (1-3 weeks) in the vitamin C group compared with control (66% vs 42%, RR 1.57, 95% CI, 1.03-2.39; low-certainty evidence) and metronidazole (62% vs 52%, RR 1.20, 95% CI, 1.03-1.41; very low-certainty evidence). Recurrence of bacterial vaginosis was lower in the vitamin C group compared with the placebo group at 6 months (16% vs 32%, RR 0.50, 95% CI, 0.27-0.93; low-certainty evidence). CONCLUSION: Treatment with intravaginal vitamin C (250 mg daily for at least 6 days) may increase cure for bacterial vaginosis in the short term and may prevent recurrence; however, additional randomized trials are needed, particularly to evaluate recurrence beyond 1 month. SYSTEMATIC REVIEW REGISTRATION: PROSPERO, CRD42024611533.