Metronidazole Dosing for Bacterial Vaginosis
For non-pregnant women of childbearing age with bacterial vaginosis, the recommended dose is metronidazole 500 mg orally twice daily for 7 days. 1
Standard Oral Regimen
- Metronidazole 500 mg orally twice daily for 7 days is the first-line treatment recommended by the Centers for Disease Control and Prevention. 1
- This regimen achieves cure rates of approximately 78-87% and provides both symptom relief and microbiologic cure. 1, 2
- The 7-day course is more effective than single-dose therapy and should be preferred for initial treatment. 1
Alternative Oral Regimens
If the standard regimen cannot be used, consider these alternatives:
- Metronidazole 2 g orally as a single dose is an alternative option, though it has lower efficacy compared to the 7-day course. 1
- Clindamycin 300 mg orally twice daily for 7 days is another alternative with comparable efficacy (cure rate 93.9%). 1
Topical Alternatives
For patients who prefer or require topical therapy:
- Metronidazole gel 0.75%, one full applicator (5 g) intravaginally once daily for 5 days is equally effective to oral therapy. 1, 3
- Clindamycin cream 2%, one full applicator (5 g) intravaginally at bedtime for 7 days achieves cure rates of 72-82%. 1, 2
Critical Patient Counseling
- Patients must avoid all alcohol consumption during metronidazole treatment and for 24 hours after completion to prevent disulfiram-like reactions (flushing, nausea, vomiting, headache). 1, 3
- Clindamycin cream and ovules are oil-based and will weaken latex condoms and diaphragms for several days after use; patients need alternative contraception during this period. 1
Special Considerations for Pregnancy
The dosing differs significantly in pregnant women:
- Metronidazole 250 mg orally three times daily for 7 days is the recommended regimen for pregnant women (after first trimester). 4, 1
- Lower doses are used in pregnancy to minimize fetal exposure while maintaining efficacy. 4
- Metronidazole is contraindicated in the first trimester; clindamycin vaginal cream should be used instead during this period. 1, 3
Follow-Up and Partner Management
- No follow-up visit is necessary if symptoms resolve completely. 1, 5
- Routine treatment of male sex partners is not recommended, as clinical trials demonstrate that partner treatment does not affect cure rates or reduce recurrence. 1, 6
Common Pitfall to Avoid
Do not confuse BV dosing with trichomoniasis dosing—while metronidazole 2 g single dose is standard for trichomoniasis, the 7-day regimen of 500 mg twice daily is preferred for BV due to superior efficacy. 1, 7