Treatment of Trichomoniasis
Preferred First-Line Treatment
The recommended treatment for trichomoniasis is metronidazole 500 mg orally twice daily for 7 days, which achieves superior cure rates (89-95%) compared to single-dose therapy and is the preferred regimen according to current CDC and ACOG guidelines. 1
Primary Treatment Options
Metronidazole 500 mg orally twice daily for 7 days is the preferred regimen, demonstrating significantly better efficacy (89% cure rate) compared to the single 2-gram dose (81% cure rate) in the highest quality randomized controlled trial 1, 2
Metronidazole 2 grams orally as a single dose is an acceptable alternative when patient compliance with multi-day therapy is unreliable, when directly observed therapy can be provided, or when cost is a significant barrier 3, 4
Tinidazole 2 grams orally as a single dose is equally effective as single-dose metronidazole (95-97% cure rates) and may be used as an alternative 5, 6
Critical Management Principles
All sexual partners must be treated simultaneously with the same regimen, regardless of symptoms, as most infected men are asymptomatic carriers. 3, 4, 1 This is the most common cause of treatment failure when neglected 3, 4
Patients must abstain from sexual intercourse until both partners complete treatment and are asymptomatic to prevent reinfection 3, 4, 1
Patients must avoid all alcohol during treatment and for at least 24 hours after metronidazole (or 3 days after tinidazole) to prevent severe disulfiram-like reactions 3, 1, 5
Both medications should be taken with food to minimize gastrointestinal side effects 5, 7
Treatment Failure Management
When treatment fails, the approach should be algorithmic:
First failure: Re-treat with metronidazole 500 mg twice daily for 7 days 3, 4, 1
Second failure: Administer metronidazole 2 grams orally once daily for 3-5 days 3, 4
Persistent failure: After excluding reinfection from untreated partners, consult an infectious disease specialist for susceptibility testing 3, 4, 1
Most treatment failures result from reinfection by untreated partners rather than drug resistance 1
Pregnancy Considerations
Metronidazole is contraindicated during the first trimester of pregnancy due to concerns about fetal organogenesis, as the drug crosses the placental barrier rapidly. 3, 1, 7
If a pregnant woman presents with symptomatic trichomoniasis during the first trimester, treatment must be delayed until the second trimester begins 3
After the first trimester: Treat with metronidazole 2 grams orally as a single dose (not the 7-day regimen) to minimize total fetal drug exposure 3, 4, 1
Treatment after the first trimester is warranted because trichomoniasis is associated with serious adverse pregnancy outcomes including premature rupture of membranes and preterm delivery 3, 1
Special Populations
HIV-infected patients should receive the same treatment regimen as HIV-negative patients 3, 1
Pediatric patients: Safety and effectiveness have not been established in children, except for amebiasis treatment 7
Elderly patients: Monitoring of serum levels may be necessary in patients with decreased liver function, as plasma clearance of metronidazole is decreased 7
Critical Pitfalls to Avoid
Metronidazole gel is contraindicated for trichomoniasis treatment and should never be used, achieving less than 50% efficacy despite being approved for bacterial vaginosis. 3, 4, 1
Topical antimicrobials other than metronidazole have even lower cure rates (<50%) and should be avoided 3, 8
Follow-up is unnecessary for patients who become asymptomatic after treatment or who are initially asymptomatic 3, 4, 1
Failure to treat partners simultaneously is the most common cause of treatment failure and reinfection 3, 4