Metronidazole Dosage for Bacterial Vaginosis and Trichomoniasis
For bacterial vaginosis, metronidazole 500 mg orally twice daily for 7 days is the recommended first-line treatment with a 95% cure rate, while for trichomoniasis, the recommended regimen is either 2 grams of metronidazole as a single oral dose or 500 mg twice daily for 7 days. 1, 2
Bacterial Vaginosis Treatment Options
Oral Metronidazole
- Metronidazole 500 mg orally twice daily for 7 days (95% cure rate) 1
- This regimen is more effective than the single 2g dose (which has only 84% cure rate) 1
Topical Metronidazole Options
- Metronidazole gel 0.75%, one full applicator (5g) intravaginally once daily for 5 days 1, 3
- Alternatively, can be administered twice daily for 5 days (equivalent efficacy to once-daily dosing) 4
Alternative Treatment
- Clindamycin cream 2%, one full applicator (5g) intravaginally at bedtime for 7 days 1
- Particularly preferred during first trimester of pregnancy 1
Trichomoniasis Treatment Options
Recommended Regimens
- Single dose: 2 grams of metronidazole orally in one dose 2
- Seven-day course: 250 mg orally three times daily for 7 days 2
- For treatment failures: Re-treat with metronidazole 500 mg twice daily for 7 days 5
- For repeated failures: Single 2g dose of metronidazole once daily for 3-5 days 5
Treatment Considerations
Efficacy Comparison
- Oral and vaginal metronidazole formulations have similar efficacy for bacterial vaginosis 6, 7
- Intravaginal application shows significantly fewer side effects than oral administration 6
Side Effects Management
- Common side effects of oral metronidazole include nausea (30.4%), abdominal pain (31.9%), and metallic taste (17.9%) 6
- Patients using metronidazole should avoid alcohol during treatment and for 24 hours afterward to prevent disulfiram-like reactions 1
Special Populations
Pregnancy
- Metronidazole is contraindicated during the first trimester of pregnancy 1, 2
- For pregnant women with trichomoniasis, 2g of metronidazole in a single dose is recommended after the first trimester 5
- Clindamycin cream 2% is preferred for BV during first trimester 1
Treatment Failures
- For trichomoniasis treatment failures, increase to metronidazole 500 mg twice daily for 7 days 5
- For persistent failures, consult with specialists and consider susceptibility testing 5
Follow-up Recommendations
- Follow-up is unnecessary for patients who become asymptomatic after treatment 5
- For pregnant women, follow-up evaluation 1 month after treatment completion is recommended 1
- Patients should abstain from sexual intercourse until treatment completion 1
- Unlike some STIs, routine treatment of male sex partners is not recommended for BV 1
- For trichomoniasis, sex partners should be treated and patients should avoid sex until both are cured 5