Treatment of Bacterial Vaginosis
Oral metronidazole 500 mg twice daily for 7 days is the preferred first-line treatment for bacterial vaginosis, achieving the highest cure rate of 95%. 1, 2
First-Line Treatment Options
The CDC recommends three equally effective first-line regimens for non-pregnant women 3, 1:
- Metronidazole 500 mg orally twice daily for 7 days - This is the preferred regimen with 95% cure rates and should be your default choice 1, 2
- Metronidazole gel 0.75%, one full applicator (5g) intravaginally once daily for 5 days - Equally efficacious as oral therapy but with fewer systemic side effects (nausea, metallic taste) 3, 1, 4
- Clindamycin cream 2%, one full applicator (5g) intravaginally at bedtime for 7 days - Another first-line option, though appears slightly less efficacious than metronidazole regimens 3, 1
Alternative Regimens (Lower Efficacy)
Use these only when compliance is a major concern or first-line options fail 3, 2:
- Metronidazole 2g orally as a single dose - Lower efficacy (84% cure rate vs. 95%) but useful for adherence issues 1, 2
- Oral clindamycin 300 mg twice daily for 7 days - Reserve for metronidazole intolerance 3, 2
- Clindamycin ovules 100g intravaginally once at bedtime for 3 days 3
Critical Treatment Precautions
Patients taking metronidazole must avoid all alcohol during treatment and for 24 hours after completion due to disulfiram-like reaction risk. 3, 1, 2 This includes mouthwash containing alcohol.
Clindamycin cream and ovules are oil-based and will weaken latex condoms and diaphragms - counsel patients to use alternative contraception during treatment and for 5 days after. 3, 1, 2
Special Populations
Pregnancy
All symptomatic pregnant women should be tested and treated for BV. 1, 2
First trimester: Use clindamycin vaginal cream 2% (one applicator at bedtime for 7 days) as metronidazole is relatively contraindicated. 1
Second and third trimesters: Metronidazole 250 mg orally three times daily for 7 days is the recommended regimen. 1, 5
High-risk pregnant women (prior preterm delivery): Treatment may reduce prematurity risk, making screening and treatment of even asymptomatic BV reasonable in this population. 3, 1, 2
Metronidazole Allergy or Intolerance
Switch to clindamycin-based regimens (cream or oral). 1, 2 Never use metronidazole vaginal gel in patients with oral metronidazole allergy - cross-reactivity occurs. 1
HIV Infection
Treat identically to HIV-negative patients using the same regimens and dosing. 3
Breastfeeding
Standard CDC guidelines apply - metronidazole is compatible with breastfeeding as only small amounts enter breast milk. 1
Partner Management
Do not routinely treat male sex partners - this has not been shown to improve cure rates or reduce recurrence. 1, 2, 5 Patients should avoid sexual intercourse until they and their partners complete treatment and are asymptomatic. 3
Follow-Up
No follow-up visit is needed if symptoms resolve. 3, 1, 2 Advise patients to return only if symptoms recur, which occurs in 50-80% of women within one year. 6, 7
Recurrent BV (≥3 episodes per year)
For documented recurrent BV, use extended therapy: 7
- Metronidazole 500 mg orally twice daily for 10-14 days, followed by
- Metronidazole vaginal gel 0.75% twice weekly for 3-6 months as suppressive therapy 7
Pre-Procedural Prophylaxis
Screen and treat BV before surgical abortion or hysterectomy in addition to routine prophylaxis, as treatment substantially reduces post-operative infectious complications including post-abortion PID. 3
Common Pitfalls to Avoid
- Do not confuse BV with cytolytic vaginosis (pH <4.0, excessive lactobacilli) - treating the latter with metronidazole will worsen symptoms 8
- Do not use the single-dose 2g metronidazole regimen as first-line - reserve it only for compliance concerns given lower efficacy 1, 2
- Do not treat asymptomatic BV in average-risk pregnant women - only high-risk (prior preterm birth) or symptomatic patients benefit 3, 1