From the Guidelines
The recommended dose of metronidazole for bacterial vaginosis is 500 mg orally twice daily for 7 days. This dose is based on the most recent and highest quality study available, which is the guideline on antimicrobial therapy of sexually transmitted diseases in Taiwan, published in 2010 1. Another option is metronidazole gel 0.75%, one applicator (5 grams) intravaginally once daily for 5 days. For patients who cannot tolerate oral metronidazole or prefer a topical treatment, the gel formulation is equally effective with fewer systemic side effects.
- Key points to consider when prescribing metronidazole for bacterial vaginosis include:
- Patients should avoid alcohol during treatment and for 24 hours afterward to prevent a disulfiram-like reaction (nausea, vomiting, flushing) 1.
- Common side effects include metallic taste, nausea, and gastrointestinal upset.
- Taking the medication with food can help minimize these effects.
- Bacterial vaginosis is caused by an imbalance in vaginal flora with overgrowth of anaerobic bacteria, and metronidazole works by disrupting bacterial DNA synthesis in these anaerobic organisms, effectively restoring normal vaginal flora.
- The Centers for Disease Control and Prevention also recommend metronidazole 500 mg orally twice a day for 7 days as a treatment option for bacterial vaginosis 1.
From the Research
Dose of Metronidazole for Bacterial Vaginosis
- The recommended dose of metronidazole for bacterial vaginosis is 500 mg orally twice daily for 7 days 2, 3.
- Alternative treatment regimens include single-dose metronidazole (2 g orally) 2, 2% clindamycin vaginal cream (once daily for 7 days) 2, 4, 0.75% metronidazole vaginal gel (twice daily for 5 days) 2, 5, and oral clindamycin (300 mg twice daily for 7 days) 2.
- For pregnant women, the recommended dose is 250 mg orally three times a day for 7 days 3.
- Once-daily dosing of 0.75% metronidazole gel 5 g for 5 days has been shown to be equivalent to twice-daily dosing in terms of efficacy, safety, and tolerance 5.
- Note that the studies 2, 3, 4, 5 focused on bacterial vaginosis, while study 6 focused on trichomoniasis, but also mentioned metronidazole treatment.