Is trichomoniasis treated with Flagyl (metronidazole)?

Treatment of Trichomoniasis with Flagyl (Metronidazole)

Yes, trichomoniasis is definitively treated with Flagyl (metronidazole), which is the only FDA-approved oral medication available in the United States for this infection and achieves cure rates of 90-95%. 1, 2

Recommended Treatment Regimens

The preferred first-line regimen is metronidazole 2 g orally as a single dose. 1, 3, 2 This provides:

• Excellent cure rates (90-95%) 1
• Better patient compliance due to single administration 4
• Lower cost 4
• FDA approval for both symptomatic and asymptomatic trichomoniasis 2

The alternative regimen is metronidazole 500 mg orally twice daily for 7 days. 1, 3 Recent high-quality evidence from 2018 demonstrates that the 7-day regimen is actually superior to single-dose therapy, with treatment failure rates of only 11% versus 19% for the single dose (relative risk 0.55, p<0.0001). 5 This suggests that for women, the 7-day regimen should be considered the preferred treatment despite traditional guidelines favoring single-dose therapy. 5

Additional FDA-approved option:

• Flagyl 375 mg orally twice daily for 7 days 1, 3

Critical Treatment Principles

Both the patient and all sexual partners must be treated simultaneously, regardless of symptoms or test results. 3, 2 This is essential because:

• Reinfection from untreated partners is the major cause of apparent treatment failure 3
• Men are frequently asymptomatic carriers, and the organism is difficult to isolate in males 2
• Negative cultures in male partners cannot be relied upon 2

Patients must abstain from sexual activity until both partners complete treatment and are asymptomatic. 3

What NOT to Use

Never use metronidazole vaginal gel as monotherapy for trichomoniasis. 1, 3, 6 The gel:

• Achieves cure rates of less than 50% compared to 90-95% with oral therapy 6, 7
• Cannot reach therapeutic levels in the urethra or perivaginal glands 1
• Is only approved for bacterial vaginosis, not trichomoniasis 1

A 2013 study of high-dose intravaginal metronidazole 750 mg combined with miconazole showed no significant difference from oral therapy 8, but this is not standard practice and oral therapy remains the gold standard.

Managing Treatment Failures

If the initial regimen fails:

1. First failure: Re-treat with metronidazole 500 mg twice daily for 7 days 1, 3
2. Repeated failure: Metronidazole 2 g orally once daily for 3-5 days 1, 3
3. Persistent failure: Consult for expert guidance and susceptibility testing 3

Before assuming treatment failure, always exclude reinfection from untreated partners. 3 Resistance does occur, with metronidazole resistance defined as MLC ≥50 μg/mL and tinidazole resistance as MLC ≥6.3 μg/mL. 9

Special Populations

Pregnant women: Can safely receive the 2 g single-dose regimen. 3 Treatment is important because trichomoniasis is associated with:

• Preterm delivery 1, 3
• Premature rupture of membranes 1, 3
• Low birth weight 3

HIV-infected patients: Use the same treatment regimens as HIV-negative patients. 3 Treatment is particularly important because untreated trichomoniasis increases HIV transmission risk. 3

Metronidazole allergy: Metronidazole desensitization under medical supervision is the recommended approach, as no effective alternative oral agents exist. 6

Follow-Up

Follow-up is unnecessary for patients who become asymptomatic after treatment. 1, 3 Only pursue follow-up if symptoms persist, which should prompt evaluation for treatment failure or reinfection.