What is the recommended dose of Flagyl (metronidazole) for bacterial vaginosis?

Flagyl Dosing for Bacterial Vaginosis

For non-pregnant women with bacterial vaginosis, the recommended dose is metronidazole (Flagyl) 500 mg orally twice daily for 7 days. 1, 2, 3

Standard Treatment Regimens

Non-Pregnant Women

• Oral metronidazole 500 mg twice daily for 7 days is the preferred systemic regimen 1, 2, 3
• Alternative options include:
  • Metronidazole 0.75% vaginal gel, one applicatorful (5 g) intravaginally twice daily for 5 days 2, 3
  • Clindamycin 2% vaginal cream, one applicatorful at bedtime for 7 days 2, 3
  • Single 2-g oral dose of metronidazole (though this may have higher relapse rates) 4

Pregnant Women - High Risk

For women with prior preterm delivery, systemic therapy is essential to treat possible subclinical upper tract infections:

• Metronidazole 250 mg orally three times daily for 7 days is the recommended regimen 5, 3
• This lower dose minimizes fetal exposure while providing systemic coverage 5
• Alternative: metronidazole 2 g single dose or clindamycin 300 mg orally twice daily for 7 days 5

Pregnant Women - Low Risk

For symptomatic women without prior preterm delivery:

• Metronidazole 250 mg orally three times daily for 7 days 5, 3
• Alternatives include metronidazole 2 g single dose, clindamycin 300 mg twice daily for 7 days, or metronidazole gel 0.75% intravaginally twice daily for 5 days 5
• Avoid clindamycin vaginal cream in pregnancy as randomized trials showed increased preterm deliveries 5

Critical Patient Counseling Points

Alcohol Avoidance

• Patients must completely avoid all alcoholic beverages during treatment and for at least 24 hours after the last dose to prevent severe disulfiram-like reactions 1

Partner Treatment

• Sex partners do not require treatment for bacterial vaginosis, as multiple trials show treating partners does not improve cure rates or prevent recurrence 1
• This distinguishes BV from sexually transmitted infections 1, 2

Expected Side Effects

• Mild gastrointestinal upset and metallic taste are common 1
• These effects are significantly reduced with vaginal gel formulations, which achieve less than 2% of oral blood levels 1

Special Considerations

HIV-Infected Patients

• Use the same treatment regimens as HIV-negative patients 5

Contraceptive Interactions

• Clindamycin vaginal cream weakens latex condoms and diaphragms 1
• Metronidazole gel does not have this interaction 1

Follow-Up and Recurrence

• No follow-up visit is necessary if symptoms completely resolve 1
• Recurrence is common, with up to 50% of women experiencing BV again within one year 1
• If symptoms return, retreatment with a recommended regimen is appropriate 1
• Avoid self-treatment with over-the-counter products 1

Common Pitfalls to Avoid

• Do not confuse BV dosing (500 mg twice daily for 7 days) with trichomoniasis dosing (2 g single dose or 500 mg twice daily for 7 days) 6, 1
• Do not use the single 2-g dose as first-line for BV, as it may have higher relapse rates compared to the 7-day regimen 4
• In pregnancy, use the lower 250 mg three times daily dose rather than the standard 500 mg twice daily to minimize fetal exposure 5, 3
• Remember that vaginal preparations are less effective than oral therapy for treating potential upper tract involvement 3