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Management of Persistent and Recurrent Trichomoniasis

Author: Christine R. Isaacs, MD

Editor: David Chelmow, MD & Eduardo Lara-Torre, MD

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Trichomonas vaginalis is a protozoan parasite and is the most common nonviral sexually transmitted infection (STI), with 3 to 5 million cases annually in the United States. Health disparities are seen among patient populations with trichomoniasis, which is more prevalent in Black women. Risk factors also include low socioeconomic status, increased number of sex partners, and douching.

Transmission of T vaginalis occurs through sexual contact. More than 50% of affected women have minimal or no symptoms. Those with symptoms often experience vulvar or vaginal irritation, malodorous yellow-green vaginal discharge, pruritis, and postcoital bleeding.

Trichomoniasis causes an elevated pH and an inflammatory green or yellow discharge that is bubbly in appearance. The recommended diagnostic test is a nucleic acid amplification test that is both sensitive (95%) and specific (95%) and can be performed on urine, vaginal, or cervical specimens. The observation of unicellular, oval, motile parasites on saline microscopy (wet mount) is less sensitive (55%-60%). Point-of-care antigen-detection commercial tests are an alternative to nucleic acid amplification tests (sensitivity 88%).

Oral nitroimidazoles (metronidazole and tinidazole in the United States) are the only approved drugs for treatment of trichomoniasis. The CDC recommended treatment is metronidazole 2g orally in a single dose or tinidazole 2g orally in a single dose. Metronidazole 500mg orally twice a day for 7 days can be used as an alternative regimen. Topically applied therapy (eg, metronidazole gel) is not effective. Due to disulfiram-like adverse effects, patients should be advised to avoid consuming alcohol for 24 hours after taking metronidazole or for 72 hours after taking tinidazole. Patients who are intolerant or allergic should be referred to a specialist for desensitization, as these medications are the only effective treatments. Expedited partner therapy may be available in certain states and should be considered.

Most women who present with continued or recurrent vaginal symptoms are likely to have been nonadherent to the medication or reinfected by exposure to an untreated partner. Rates of reinfection are as high as 17%. When reinfection is suspected, repeating the basic treatment regimen should be adequate. Patients should be instructed to abstain from sex until their sex partner(s) have completed therapy and both the patient and the partner are asymptomatic. Because of the high rate of reinfection, retesting for T vaginalis is recommended within 3 months following initial treatment. Testing for other STIs, including HIV, should be offered.

Some recurrent infections may be due to organisms with decreased sensitivity to nitroimidazoles. This has been identified in 2% to 5% of vaginal trichomoniasis cases. High-level antimicrobial resistance also rarely occurs. If decreased sensitivity or resistance is suspected, tinidazole can be effective if repeated treatment with metronidazole, 500 mg twice daily for 7 days, fails. If adherence is confirmed and repeated treatment is not successful, sending a culture to a reference laboratory for susceptibility testing can be considered. In rare cases in which infection persists despite extended treatment regimens, consultation and susceptibility testing is available through the Centers of Disease Control (telephone: [404] 718-4141; website:

While there are no evidence-based guidelines to guide treatment of male partners of women with nitroimidazole treatment failure, the Centers for Disease Control recommend male partner evaluation and treatment with either a single dose of tinidazole, 2 g, or metronidazole, 2 g. An alternate regimen of Metronidazole 500 mg orally twice a day for 7 days may also be utilized.

Further Reading:

Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines. MMWR 2015;64 (No. RR 3):72-75. Available at: Verified March 2021

Vaginitis in Nonpregnant Patients: ACOG Practice Bulletin, Number 215. Obstet Gynecol. 2020 Jan;135(1):e1-e17. doi: 10.1097/AOG.0000000000003604. PMID: 31856123.

Initial approval: January 2015
Reaffirmed: September 2016
Revised: January 2018
Minor Revision: July 2019

Revised: March 2021, final editing provided by The Medical Pen, LLC.


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