Treatment of Trichomoniasis in Patients on PrEP and Doxycycline
Oral metronidazole 2g as a single dose is the recommended treatment for trichomoniasis in patients with green discharge, including those on PrEP and doxycycline. 1
First-Line Treatment Options
The Centers for Disease Control and Prevention recommends the following regimens for trichomoniasis:
- First-line treatment: Metronidazole 2g orally in a single dose (cure rates 90-95%) 2, 1
- Alternative regimen: Metronidazole 500mg orally twice daily for 7 days 2, 1
These recommendations apply to patients regardless of their PrEP or doxycycline use status. There are no known clinically significant interactions between metronidazole and either PrEP medications or doxycycline that would contraindicate this treatment approach.
Why Oral Treatment is Preferred Over Injection
- Injectable treatments are not recommended in current guidelines for trichomoniasis
- Metronidazole is the only FDA-approved medication in the United States for trichomoniasis treatment 2
- Topical metronidazole preparations (including gels) are NOT effective for trichomoniasis (<50% efficacy) and should not be used 2, 1
Clinical Considerations
Diagnosis Confirmation
- Green discharge is consistent with trichomoniasis, which characteristically causes a diffuse, malodorous, yellow-green discharge with vulvar irritation 2, 1
- Confirm diagnosis through one of these methods:
- Microscopic examination (60-70% sensitivity)
- Culture (more sensitive)
- Nucleic acid amplification tests (NAATs) - highest sensitivity 1
Treatment Considerations
- Concurrent treatment of all sexual partners is essential to prevent reinfection 1
- Patients should abstain from sexual activity until:
- Both patient and partner(s) complete treatment
- All parties are asymptomatic 1
Management of Treatment Failure
If treatment failure occurs:
- Re-treat with metronidazole 500mg twice daily for 7 days 2, 1
- For repeated failures, use metronidazole 2g once daily for 3-5 days 2, 1
- For persistent infections, consider testing for metronidazole susceptibility 1, 3
Special Considerations
Metronidazole Allergy
- For patients with metronidazole allergy, tinidazole 2g orally in a single dose is an alternative 1, 3
- For severe metronidazole allergy or resistance, consultation with an infectious disease specialist is recommended 3
Follow-up
- Routine follow-up is unnecessary for patients who become asymptomatic after treatment 2, 1
- Improvement in symptoms should be seen within 72 hours of starting treatment 1
Remember that while the patient is on doxycycline (likely for STI prophylaxis), this medication has no meaningful activity against Trichomonas vaginalis and should not be considered as treatment for the current infection.