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Clinician

Blog articles for clinicians and other medical professionals.

What Clinicians Should Know About Trichomoniasis Treatment

August 18th, 2025

This article offers an in-depth overview of trichomoniasis for clinicians, focusing primarily on treatment strategies, but also covering essential background topics, such as etiology, clinical presentation, and diagnostic considerations.

Understanding trichomoniasis: Etiology and epidemiology

Trichomoniasis is caused by Trichomonas vaginalis, a flagellated protozoan parasite transmitted primarily through vaginal intercourse. The Centers for Disease Control and Prevention (CDC) estimates that around 2.6 million people in the U.S. are infected per year, with higher prevalence rates observed in women, individuals with multiple sexual partners, and those with other STIs.

The infection predominantly affects the urogenital tract. In women, it colonizes the vagina, urethra, and paraurethral glands; in men, it typically resides in the urethra, prostate, and occasionally the epididymis.

Risk factors include:

  • Unprotected sexual intercourse
  • Multiple sexual partners
  • A history of STIs
  • In women, vaginal douching (which may disrupt the normal vaginal microbiota)

Clinical presentation: Signs and symptoms

Trichomoniasis presents a diagnostic challenge due to its variable symptomatology. Around 70% of infected individuals are asymptomatic or experience only mild symptoms. When symptomatic, the clinical presentation differs by sex:

In female patients

  • Vulvovaginal irritation, itching, or burning
  • Dysuria
  • Frothy, yellow-green vaginal discharge with a characteristic odor
  • Dyspareunia
  • Vaginal erythema and punctate cervical hemorrhages (“strawberry cervix”), seen in up to 25% of cases

In male patients

  • Dysuria
  • Irritation inside the penis
  • Urethral discharge
  • Post-ejaculatory discomfort

In both sexes, trichomoniasis can persist for months or even years without treatment, serving as a reservoir for transmission and increasing susceptibility to other infections, notably HIV.

Diagnostic evaluation

Accurate diagnosis of trichomoniasis is essential to guide appropriate treatment and reduce transmission. Diagnostic methods include:

  • Wet mount microscopy: This traditional method detects motile trichomonads in vaginal fluid but has limited sensitivity (~50–60%).
  • Culture: Previously the gold standard, T. vaginalis culture has largely been supplanted by nucleic acid amplification tests (NAATs).
  • NAATs: These are now the preferred diagnostic tests due to their high sensitivity and specificity. The Aptima T. vaginalis assay, for example, is Food and Drug Administration (FDA) approved and can detect infections in all patient populations.
  • Point-of-care antigen tests: These are useful in settings lacking laboratory infrastructure, and results are available in about 10 to 15 minutes.

Given the limitations of microscopy and the high sensitivity of NAATs, most clinical guidelines now recommend NAAT as the first-line diagnostic tool, especially in high-risk or symptomatic patients.

Treatment of trichomoniasis: Current guidelines and considerations

First-line therapy

The cornerstone of trichomoniasis treatment remains nitroimidazole antibiotics, specifically metronidazole and tinidazole, both of which are effective against T. vaginalis due to their anaerobic-targeting mechanisms.

The CDC recommends the following:

  • Metronidazole
    • Men single-dose regimen: 2 g orally in a single dose (most commonly prescribed)
    • Women: 500 mg orally twice daily for seven days
  • Tinidazole
    • Men and women single-dose regimen: 2 g orally in a single dose

While single-dose therapy is convenient and improves adherence, recent evidence suggests that the seven-day metronidazole regimen may be more effective in certain populations — women, particularly women with HIV, who tend to experience higher rates of treatment failure with the single-dose regimen.

Treatment recommendations by population

  1. Women (non-HIV)
    1. Preferred: Metronidazole 500 mg orally twice daily for seven days
    2. Consider: Tinidazole 2 g orally in a single dose
  2. Women with HIV
    1. Preferred: Metronidazole 500 mg orally twice daily for seven days
    2. Enhanced efficacy and reduced recurrence in this subgroup
  3. Men
    1. Preferred: Metronidazole 2 g orally once
    2. Tinidazole 2 g orally once is an effective alternative
  4. Pregnant women
    1. Preferred: Metronidazole 2 g orally in a single dose
    2. Though concerns about teratogenicity have historically limited its use in the first trimester, current CDC guidelines and available evidence support its safety when clinically indicated.
  5. Breastfeeding women
    1. Tinidazole should be avoided due to prolonged excretion in breast milk. If metronidazole is used, clinicians may advise withholding breastfeeding for 12 to 24 hours post-dose, depending on the regimen.

Partner management

Partner treatment is essential to prevent reinfection. All sexual partners within the past 60 days should be treated, even if asymptomatic. The CDC recommends simultaneous treatment of sexual partners and refraining from intercourse until both partners have completed therapy and are symptom-free.

Expedited partner therapy (EPT) may be considered, particularly in jurisdictions where it is legally and clinically appropriate. EPT involves providing medication or prescriptions to the index patient for their partner(s) without prior medical evaluation.

Management of refractory and recurrent infections

Treatment failure can occur in some cases and may result from reinfection, antimicrobial resistance, or inadequate partner treatment. Clinicians should differentiate between reinfection and drug resistance through careful history-taking and, if possible, microbial susceptibility testing.

Suggested approach

  1. Ensure adherence to prior therapy and confirm that sexual partners were treated.
  2. Repeat treatment with higher or prolonged doses:
    1. Metronidazole 500 mg orally twice daily for seven days if initial therapy was a single 2 g dose
  3. If persistent after repeat therapy:
    1. Tinidazole 2 g orally daily for five days
    2. Or metronidazole 2 g orally daily for seven days

If resistance is suspected, the CDC offers drug susceptibility testing via the Division of Parasitic Diseases and Malaria. For these patients, referral to an infectious disease specialist or STI expert may be warranted.

Special considerations: Co-infections and comorbidities

Trichomoniasis is often diagnosed alongside other STIs, including chlamydia, gonorrhea, syphilis, and HIV. Coinfection with HIV is particularly significant, as trichomoniasis increases genital shedding of HIV and may enhance transmission risk. Thus, routine STI screening and comprehensive sexual health counseling should accompany any trichomoniasis diagnosis.

Patients diagnosed with trichomoniasis should undergo full STI screening, including testing for HIV, syphilis, gonorrhea, and chlamydia, as per CDC guidelines. Retesting for T. vaginalis is advised at three months post-treatment, particularly in women, due to high rates of reinfection.

Emerging therapies and research

While metronidazole and tinidazole remain the mainstays of therapy, growing concern about resistance and intolerance underscores the need for new treatment options. Investigational agents such as secnidazole, a long-acting nitroimidazole already approved for Bacterial Vaginosis, are under evaluation for use in trichomoniasis.

An ongoing randomized controlled trial is currently evaluating the safety and efficacy of secnidazole 2g single-dose therapy compared to standard metronidazole treatment in female patients with trichomoniasis. Preliminary findings suggest comparable efficacy with improved gastrointestinal tolerability.

Another investigational approach involves combination therapy. A recent phase II pilot study (NIH-funded, in progress as of 2024) is testing a dual-therapy regimen combining metronidazole with boric acid vaginal suppositories. The hypothesis is that restoring vaginal acidity and microbiota may improve treatment outcomes, particularly in cases of recurrent or treatment-resistant trichomoniasis.

Additionally, researchers are exploring the role of the vaginal microbiome in modulating infection susceptibility and recurrence. A small-scale RCT is testing the use of oral and vaginal lactobacilli supplementation post-antibiotic therapy to reduce recurrence rates.

These studies reflect a broader movement toward individualized care based on host-pathogen-microbiota interactions and suggest that future therapies may integrate antimicrobial and microbiome-supportive strategies for optimal outcomes.

Overview and recap

Trichomoniasis is a prevalent but frequently overlooked STI with significant public health implications. For clinicians, timely diagnosis, effective treatment, and partner management are crucial to controlling the spread and preventing complications.

While metronidazole and tinidazole remain the cornerstone of therapy, clinicians should consider treatment nuances based on patient-specific factors such as HIV status, pregnancy, recurrence, and resistance patterns. Ongoing research into novel therapies and the role of the vaginal microbiome may offer new strategies in the future.

By maintaining a high index of suspicion and following evidence-based treatment protocols, clinicians can significantly reduce the burden of trichomoniasis and its sequelae in both individuals and communities.

References

  • Kissinger, P. et al. (2018). Single-dose versus 7-day-dose metronidazole for the treatment of trichomoniasis in women: An open-label, randomised controlled trial. The Lancet Infectious Diseases. Retrieved from https://pubmed.ncbi.nlm.nih.gov/30297322/
  • Muzny, C., Schwebke, J., Nyirjesy, P., et al. (2021). Efficacy and safety of single oral dosing of secnidazole for trichomoniasis in women: Results of a phase 3, randomized, double-blind, placebo-controlled, delayed-treatment study. Clinical Infectious Diseases. Retrieved from https://pubmed.ncbi.nlm.nih.gov/33768237/
  • Stapleton, A., Au-Yeung, M., Hooton, T. M., et al. (2011). Randomized, placebo-controlled phase 2 trial of a Lactobacillus crispatus probiotic given intravaginally for prevention of recurrent urinary tract infection. Clinical Infectious Diseases. Retrieved from https://pubmed.ncbi.nlm.nih.gov/21498386/