Trichomoniasis treatment is a course of oral antiparasitic pills. The CDC recommends metronidazole twice daily for seven days for women, and a single larger dose for men; tinidazole as a single dose is an alternative for either. Skip alcohol during treatment, treat all partners at the same time, and finish every pill.
most common curable STI
metronidazole / tinidazole
retest
| Item | Value |
|---|---|
| Estimated US infections | ~2.6 million — most common curable STI |
| Have no symptoms | ~70% |
| Cure | >90% — metronidazole / tinidazole |
| Reinfected within 3 mo | ~1 in 5 — retest |
The essentials: what trichomoniasis is and why treatment works
Trichomoniasis is caused by Trichomonas vaginalis, a single-celled protozoan parasite. It's neither a bacterium nor a virus, and that shapes treatment: it responds to a specific class of nitroimidazole drugs (metronidazole and tinidazole) rather than the antibiotics used for chlamydia or gonorrhea. It's the most common curable non-viral STI in the United States, with an estimated 2.6 million infections, and it falls disproportionately on women, who account for over 80% of cases Sex Transm Dis, 2018.
Because the medication kills the parasite directly, a completed course clears the infection in nearly everyone. Reinfection is the real problem. Trich pings back and forth between partners easily, so treating you alone while a partner stays infected is the most common reason people end up positive again a few weeks later CDC, About Trichomoniasis.
Symptoms: what trich actually feels like
About 70% of infected people have no signs or symptoms at all, so many cases turn up only on a routine screen. When symptoms do show up, they tend to be irritating rather than dramatic, and they're easy to confuse with other vaginal conditions.
In women, trich can cause itching, burning, redness or soreness around the genitals, discomfort while urinating, and a discharge that may be clear, white, yellowish, or greenish, often with a noticeable fishy smell. That fishy odor overlaps heavily with bacterial vaginosis, and the itch can mimic a yeast infection, so guessing is risky. If you're trying to sort out what's going on, compare the patterns of bv discharge vs yeast infection vs trich before you self-treat with anything from the drugstore.
In men, trich is usually silent. When it does cause symptoms, you might notice itching or irritation inside the penis, burning after urinating or ejaculating, or a thin discharge. Because men so often feel nothing, an infected male partner can carry and pass the parasite without any clue he has it. That's one more reason both partners need treatment.
Testing: how trich is diagnosed
The preferred test is a nucleic acid amplification test (NAAT), for example the Aptima T. vaginalis assay, which detects the parasite's genetic material with a sensitivity around 95–100% CDC STI Tx Guidelines, 2021. That's far more sensitive than the older method of looking for moving parasites under a microscope (a wet mount), which misses a meaningful share of true infections. Acceptable specimens include a vaginal swab or a female urine sample.
In practice, getting tested is low-drama: a urine cup, a self-collected swab, or a quick exam, with results usually back in a few days. It's free or low-cost at health departments, Planned Parenthood, and Title X clinics. If you've had a recent exposure and aren't sure whether enough time has passed for a reliable result, check the guidance on when to test after exposure so you don't test too early and get false reassurance. When you're ready, you can get tested and ask specifically for a trich NAAT, which isn't always included in a standard panel, so name it. For the full step-by-step on sampling and result timing, see trichomoniasis testing & diagnosis.
Treatment: single dose vs the 7-day course
The 2021 CDC guidelines changed the regimen. For years, everyone got a single 2 g dose of metronidazole. The recommended regimen now splits by sex, because the science showed women do better on a longer course.
For women, the recommended treatment is metronidazole 500 mg orally twice daily for seven days. The shift away from the single dose came from a randomized trial: about 19% of women given the single 2 g dose were still infected at follow-up, versus 11% on the seven-day course, roughly halving the retest-positive rate Muzny et al., Sex Transm Dis. For men, a single 2 g oral dose of metronidazole is still recommended. Tinidazole as a single 2 g oral dose is an alternative for either sex.
| Who | Recommended regimen | Alternative |
|---|---|---|
| Women | Metronidazole 500 mg orally, twice daily, for 7 days | Tinidazole 2 g orally, single dose |
| Men | Metronidazole 2 g orally, single dose | Tinidazole 2 g orally, single dose |
A few rules make or break the cure. Do not drink alcohol during treatment with metronidazole or tinidazole; combining either with alcohol can trigger a disulfiram-like reaction (flushing, nausea, vomiting, racing heart). Finish the whole course even after you feel better, because stopping early leaves parasites behind. Beyond the pills, treat all sex partners at the same time, so you're not re-infected the moment you have sex again.
Because reinfection is so common, the CDC recommends that sexually active women be retested about three months after treatment. The point is to catch a fresh infection picked up from an untreated or new partner, not to check whether the cure failed. Clinics handle it every day.
Prevention: keeping it from coming back
Trich spreads through genital contact, so correct, consistent condom use every time you have sex lowers your risk. Condoms aren't perfect and they don't cover every area of contact, but used reliably they cut transmission substantially.
- Use condoms every time rather than sometimes, since partial use offers only partial protection.
- Make sure every current partner is treated before you resume sex, even if they feel fine.
- Screen if you're in an at-risk group, since routine testing catches the roughly 70% of infections that cause no symptoms.
- Don't assume that 'no symptoms' means 'no infection.' Most carriers feel nothing.
When to see a clinician
See a clinician if you have new genital itching, burning, abnormal discharge, or pain with urination, especially with a fishy odor. Get checked if a partner was diagnosed with trich, if you've had unprotected sex with a new partner, or if you tested positive and want a retest at the three-month mark. Pregnant people with symptoms should be evaluated, since untreated trich in pregnancy can affect outcomes. And if your prescribed course didn't clear your symptoms, go back; your clinician can confirm whether it's reinfection, a missed partner, or something else entirely.