Trichomoniasis is the most common curable sexually transmitted infection (STI) in the United States. This infection is caused by the single-celled protozoan parasite Trichomonas vaginalis. Though highly treatable, the infection frequently goes unnoticed because approximately 70% of infected individuals show no signs or symptoms. This allows the parasite to be unknowingly passed to others, making adherence to treatment protocols essential for a complete cure and prevention.
Understanding Trichomoniasis and Treatment Basics
Treatment for trichomoniasis involves oral antibiotics from the nitroimidazole class, primarily metronidazole or tinidazole. Treatment is administered either as a single, high-dose regimen taken all at once, or as a multi-dose course spread over seven days. The Centers for Disease Control and Prevention (CDC) often recommends the seven-day course of metronidazole (500 mg taken twice daily), particularly for women, as this regimen has demonstrated higher cure rates.
The effectiveness of treatment hinges entirely on completing the full course exactly as directed by a healthcare provider. Patients must take every pill, even if symptoms begin to clear quickly. Alcohol consumption must be avoided while on these medications and for at least 24 to 72 hours after the final dose, depending on the specific drug. This prevents severe side effects like nausea and vomiting and ensures the treatment’s success.
The Required Waiting Period for Sexual Activity
After successfully completing the antibiotic regimen, patients must abstain from all sexual activity for a minimum of seven days. This period of abstinence ensures the medication has completely cleared the parasitic infection from the body. Sexual contact before this period ends risks reintroducing the parasite and rendering the treatment ineffective.
The waiting period begins after the completion of the full course of medication, not when the patient first starts taking the pills. For a single, one-time dose, the seven-day waiting period begins the day after the dose is swallowed. If prescribed a seven-day course, the patient must wait seven full days after taking the very last pill. This seven-day rule must also be followed only once all symptoms have fully resolved.
This period of sexual rest applies to all forms of sexual contact, including vaginal, anal, and oral sex. Barrier methods are not sufficient protection during the post-treatment phase. Both the treated individual and all sexual partners must complete their full course of medication and observe the required seven-day waiting period before resuming activity.
Why Partner Treatment is Non-Negotiable
Treating only the infected individual is insufficient because the parasite can easily be passed back and forth between partners. If a person is treated but their sexual partner is not, re-infection is highly likely, wasting the initial treatment and necessitating another full round of antibiotics. This re-exposure can also lead to issues with treatment resistance over time.
For treatment to be successful, all sexual partners from the previous 60 days must be promptly notified, tested, and treated simultaneously. Even asymptomatic partners can still harbor and transmit the parasite. In situations where a partner is unlikely or unable to seek a medical evaluation, Expedited Partner Therapy (EPT) may be used. EPT allows the healthcare provider to give the patient a prescription or medication to deliver to their partner, ensuring they receive treatment without an immediate visit to a clinic.
The Importance of a Test of Cure
Medical guidelines recommend follow-up testing due to the high rate of reinfection; approximately one in five people treated for trichomoniasis become infected again within three months. This high recurrence rate is why a Test of Cure (TOC), or rescreening, is strongly recommended for all sexually active women.
The TOC is typically scheduled three months after the initial treatment is completed. This timing allows for the detection of a new infection while avoiding false-positive results that occur if testing is done too soon. Highly sensitive tests, like Nucleic Acid Amplification Tests (NAATs), can sometimes detect residual genetic material from non-living parasites if performed within a few weeks of treatment. The three-month window confirms the infection is truly cleared or identifies a persistent infection requiring further management.