What is the dosage of Flagyl (metronidazole) for trichomoniasis?

Metronidazole Dosage for Trichomoniasis Treatment

The recommended first-line treatment for trichomoniasis is metronidazole 2 g orally in a single dose. 1

Treatment Options

First-Line Regimen:

• Metronidazole 2 g orally in a single dose 1, 2
  • Cure rates: approximately 90-95% 1
  • Advantages: ensures compliance, can be directly observed

Alternative Regimen:

• Metronidazole 500 mg orally twice daily for 7 days 1, 2
  • Similar efficacy to single-dose regimen
  • May be preferred in certain clinical scenarios

FDA-Approved Alternative:

• Flagyl 375 mg twice daily for 7 days 1
  • Pharmacokinetically equivalent to metronidazole 250 mg three times daily for 7 days
  • Note: No clinical data confirming clinical equivalency

Treatment Selection Considerations

Recent evidence suggests that the 7-day regimen may be more effective than the single-dose treatment. A 2018 randomized controlled trial found that patients in the 7-day-dose group were less likely to be T. vaginalis positive at follow-up compared to those in the single-dose group (11% vs 19%) 3.

A meta-analysis from 2017 also indicated higher treatment failure for single-dose compared to multi-dose regimens (risk ratio 1.87) 4.

Special Populations

Pregnancy:

• Pregnant patients should not be treated during the first trimester 2
• For pregnant patients beyond first trimester: 2 g metronidazole in a single dose 1
• Note: The one-day course should not be used in pregnant patients when alternative treatment has been inadequate, as it results in higher serum levels that can reach fetal circulation 2

HIV Infection:

• Same treatment regimen as HIV-negative patients 1

Management of Sex Partners

• Sex partners should be treated 1
• Patients should avoid sex until both they and their partners are cured 1
• In the absence of a test of cure, this means waiting until therapy is completed and both patient and partner(s) are asymptomatic 1

Follow-Up Recommendations

• Follow-up is unnecessary for patients who become asymptomatic after treatment 1
• If treatment failure occurs with either regimen, re-treat with metronidazole 500 mg twice daily for 7 days 1
• For repeated treatment failures, consider metronidazole 2 g once daily for 3-5 days 1

Treatment Failures

For patients with persistent infection despite appropriate treatment:

1. Rule out reinfection
2. Consider metronidazole resistance
3. Consult with an expert for management of resistant cases
4. Consider susceptibility testing of T. vaginalis to metronidazole 1

Important Considerations

• Metronidazole is the only oral medication available in the United States for treating trichomoniasis 1
• Topical metronidazole gel is NOT recommended for trichomoniasis as it cannot achieve therapeutic levels in the urethra or perivaginal glands 1
• For patients allergic to metronidazole, desensitization may be necessary as effective alternatives are not available 1

When repeat courses are required, allow 4-6 weeks between courses and reconfirm the presence of trichomonads before retreatment 2.