Trichomonas Treatment
Treat with metronidazole 500 mg orally twice daily for 7 days, which achieves superior cure rates (89-97%) compared to single-dose therapy and should be the preferred regimen for all patients. 1, 2, 3
Primary Treatment Regimen
- Metronidazole 500 mg orally twice daily for 7 days is the recommended first-line treatment, achieving cure rates of 89-97% 4, 1, 3
- This multi-dose regimen demonstrates significantly lower treatment failure rates compared to single-dose therapy (11% vs 19% failure, relative risk 0.55, p<0.0001) 3
- The 7-day regimen should be taken with food to minimize gastrointestinal side effects 4
Alternative Regimen
- Metronidazole 2 g orally as a single dose can be used as an alternative, achieving 90-95% cure rates, though this is less effective than the 7-day regimen 4, 2
- Single-dose therapy has nearly double the treatment failure rate compared to 7-day therapy (pooled risk ratio 1.87,95% CI 1.23-2.82) 5
- Despite lower efficacy, single-dose therapy may be appropriate when adherence to multi-dose regimens is unlikely 6, 7
Alternative Agent
- Tinidazole 2 g orally as a single dose is FDA-approved for trichomoniasis treatment and should be taken with food 8
- Sexual partners must be treated simultaneously with the same dose to prevent reinfection 8
Critical Patient Instructions
- Patients must avoid all alcoholic beverages during treatment and for at least 24 hours after the last metronidazole dose (72 hours for tinidazole) to prevent severe disulfiram-like reactions 1, 9, 8
- Patients must abstain from sexual intercourse until both they and all partners complete treatment and are asymptomatic 4, 1, 9
- Nausea (23%), headache (7%), and vomiting (4%) are the most common side effects 3
Mandatory Partner Management
- All sexual partners must be treated simultaneously with the same regimen, regardless of symptoms or test results 4, 1, 2, 9
- Most infected men are asymptomatic carriers, making partner treatment essential even without confirmed infection 4, 1, 9
- Failure to treat partners is the most common cause of treatment failure and reinfection 9
Management of Treatment Failure
- If initial treatment fails, re-treat with metronidazole 500 mg twice daily for 7 days 4, 1
- For repeated treatment failure, use metronidazole 2 g once daily for 3-5 days 4, 1
- Patients with culture-documented infection who fail the 3-5 day regimen and have excluded reinfection should be managed in consultation with an expert, with susceptibility testing of T. vaginalis to metronidazole 4
Pregnancy Considerations
- Metronidazole is contraindicated during the first trimester of pregnancy due to concerns about fetal organogenesis 4, 9
- After the first trimester, treat with metronidazole 2 g orally as a single dose to minimize total fetal drug exposure 4, 2, 9
- Treatment after the first trimester is warranted because trichomoniasis is associated with premature rupture of membranes and preterm delivery 4, 9
- If symptomatic trichomoniasis presents during the first trimester, treatment must be delayed until the second trimester begins 9
HIV-Infected Patients
Metronidazole Allergy
- Effective alternatives to metronidazole are extremely limited 4, 1
- Patients with immediate-type allergy to metronidazole can be managed by desensitization protocols 4, 1
- Topical therapy with non-nitroimidazole drugs has cure rates below 50% and is not recommended 4
Follow-Up
- Routine follow-up is unnecessary for patients who become asymptomatic after treatment 4, 2
- If symptoms persist, re-evaluate for treatment failure or reinfection 2
Common Pitfalls
- Avoid topical metronidazole gel, which achieves less than 50% cure rates because it cannot reach therapeutic levels in the urethra or perivaginal glands 4
- Do not use single-dose therapy as first-line treatment given the significantly higher failure rates demonstrated in recent high-quality trials 3, 5
- Ensure simultaneous partner treatment as untreated partners will reinfect treated patients 9