Patient Education: Trichomoniasis Treatment with Metronidazole
What is Trichomoniasis?
Trichomoniasis (often called "trich") is a sexually transmitted infection caused by a parasite called Trichomonas vaginalis. 1 Most men with trich have no symptoms, but many women experience a yellow-green vaginal discharge with a bad odor, along with vaginal and vulvar irritation. 1
Treatment for Women and Men
Both women and men should be treated with metronidazole 500 mg taken by mouth twice daily for 7 days—this is the most effective treatment regimen with cure rates of 90-95%. 2, 3 This 7-day regimen is superior to the single-dose option and is now the preferred treatment according to the Centers for Disease Control and Prevention. 2
Alternative Treatment Option
- An alternative is a single 2-gram dose of metronidazole taken all at once, though this has slightly lower cure rates (approximately 86-93% compared to 90-95% for the 7-day regimen). 2, 3, 4, 5
- The single-dose option may be used when medication adherence is a concern or when directly observed therapy is needed. 6
Critical Rules for Successful Treatment
Your sexual partner(s) MUST be treated at the same time as you, even if they have no symptoms. 2, 6 This is the most important rule—failure to treat partners is the most common reason trich comes back. 2
During Treatment You Must:
- Abstain from all sexual activity until both you and your partner(s) complete the full treatment course and have no symptoms. 2, 6
- Avoid all alcohol during treatment and for at least 24 hours after your last dose. 7, 6 Metronidazole can cause a severe reaction with alcohol that includes nausea, vomiting, flushing, headache, and abdominal cramps. 7, 6
- Take all medication exactly as prescribed, even if symptoms improve before finishing. 2
What If Treatment Doesn't Work?
If symptoms persist after completing treatment: 2, 6
- First treatment failure: Retreat with metronidazole 500 mg twice daily for 7 days. 2, 6
- Second treatment failure: Take metronidazole 2 grams once daily for 3-5 days. 2, 6
- Continued failure: See a specialist for evaluation—you may have a resistant infection that requires susceptibility testing. 7, 6
Follow-Up Care
You do not need a follow-up appointment if your symptoms completely resolve after treatment. 2, 6 Only return to your healthcare provider if symptoms persist, which may indicate reinfection from an untreated partner or a resistant infection. 2, 7
Important Warnings and Common Mistakes
Do NOT Use:
- Vaginal metronidazole gel—it does NOT work for trichomoniasis (less than 50% effective) and should never be used. 2, 7, 6 The gel cannot reach the infection in the urethra and other glands where the parasite lives. 2
Special Situations:
- Pregnancy: Metronidazole should NOT be used in the first trimester of pregnancy. 1, 7 After the first trimester, a single 2-gram dose can be safely used. 1, 7, 6
- HIV infection: If you have HIV, you receive the same treatment as HIV-negative patients. 1, 7, 6
- Metronidazole allergy: If you have a true allergy to metronidazole, you may need desensitization therapy since there are no effective alternative medications available in the United States. 7, 6, 8
Why Both Partners Need Treatment
Trichomoniasis is a sexually transmitted infection, meaning it passes between sexual partners. 8 Even if your male partner has no symptoms and tests negative, he can still carry and transmit the infection. 1 Women frequently become reinfected if their partner is not treated simultaneously. 1, 8