Trichomoniasis symptoms, when they show up, include vaginal itching, burning, soreness, painful urination, and a clear, white, yellowish or greenish discharge with a fishy odor in women; men may notice itching inside the penis or burning after peeing or ejaculating. About 70% of infected people have no symptoms at all CDC.
with the right treatment
testing, not symptoms, decides
| Item | Value |
|---|---|
| Curable? | yes — with the right treatment |
| Tested by | NAAT / lab |
| Often | no symptoms |
| If you may have it | get tested — testing, not symptoms, decides |
What trichomoniasis is
Trichomoniasis is an infection caused by a single-celled parasite called Trichomonas vaginalis, a protozoan rather than a bacterium or a virus. It moves between people during sex and sets up shop in the lower genital tract: the vagina and urethra in women, the urethra inside the penis in men. Because it's a living parasite, the right medication cures it outright.
It's also extremely common. Trich is the most common curable non-viral STI in the US, with an estimated 2.6 million infections Sex Transm Dis, 2018. It lands disproportionately on women, who account for over 80% of cases. For the full clinical picture, see our overview of trichomoniasis.
Symptoms — and the silent reality
Most infections are invisible. About 70% of people carrying the parasite feel nothing, so you can have it, and pass it, without a single sign. A symptom check is never a substitute for a test.
When symptoms do appear, the parasite irritates the genital lining and triggers inflammation. In women that shows up as itching, burning, redness or soreness of the genitals, discomfort while urinating, and a discharge that may be clear, white, yellowish or greenish, often with a fishy smell. The odor and discharge send many women to a clinic.
In men, symptoms are usually milder or absent. When present, they include itching or irritation inside the penis, a burning feeling after urinating or ejaculating, and sometimes a discharge. Men are commonly asymptomatic carriers, one of the main reasons the infection keeps bouncing between partners.
Timing is unpredictable. Symptoms, when they happen, may appear roughly 5 to 28 days after infection, but they can show up much later or never. If you're trying to figure out the right moment to get checked after a possible exposure, our guide on when to test after exposure walks through the windows.
How trichomoniasis spreads
Trich spreads through sexual contact: penis-to-vagina, vagina-to-penis, and vagina-to-vagina. It travels in genital fluids, passing when those fluids make contact during sex. It does not spread through casual contact like toilet seats or sharing food.
Because so many carriers have no symptoms, reinfection between partners, the "ping-pong" pattern, is the rule rather than the exception. One partner gets treated, sleeps with an untreated partner, and is reinfected within weeks. Treating everyone at the same time matters for this reason.
How trichomoniasis is tested
The preferred test is a NAAT (nucleic acid amplification test), which detects the parasite's genetic material. The Aptima T. vaginalis assay, for example, has sensitivity around 95–100% CDC STI Guidelines, 2021. Specimens include a vaginal swab or a female urine sample, so collection is quick and minimally invasive.
In practice, testing is simple: a urine cup, a self-collected swab, or a brief exam, with results usually back in a few days. It's free or low-cost at health departments, Planned Parenthood, and Title X clinics. The CDC recommends routine annual screening for asymptomatic women living with HIV, since trich and HIV interact in ways that raise risk on both sides.
For the step-by-step on samples, accuracy, and what the lab is actually doing, see trichomoniasis testing & diagnosis. When you're ready, you can get tested or compare testing providers to find an option that fits.
Treatment
Trich is curable with oral medication. For women, the recommended regimen is metronidazole 500 mg twice daily for 7 days. For men, the standard is a single 2 g oral dose of metronidazole. Either sex can alternatively take a single 2 g oral dose of tinidazole.
The shift to a multi-day course for women is recent and evidence-driven. The 2021 guidelines moved women off the old single 2 g dose because the 7-day course halved retest-positive rates. In a randomized trial, about 19% of women given the single dose were still infected at follow-up versus 11% on the 7-day course Muzny et al..
| Group | Recommended regimen | Alternative |
|---|---|---|
| Women | Metronidazole 500 mg twice daily for 7 days | Tinidazole 2 g single dose |
| Men | Metronidazole 2 g single dose | Tinidazole 2 g single dose |
A few rules make or break the cure. Skip alcohol during metronidazole or tinidazole treatment, since combining them can cause a disulfiram-like reaction with nausea, vomiting, and flushing. Finish the whole course even after you feel better. Treat all sex partners at the same time so you don't trade it back and forth, and plan to retest sexually active women about three months after treatment, because reinfection is common. The full breakdown lives in our guide to trichomoniasis treatment.
Complications if untreated
Left alone, trich does more than cause discomfort. It increases the risk of getting or spreading other STIs, including HIV. The inflammation it causes makes the genital tissue more vulnerable to other infections and easier for the virus to enter or exit.
In pregnancy, the stakes are higher. Trichomoniasis increases the chance of preterm birth (delivery before the baby is fully developed) and low birth weight (a smaller, more fragile newborn). Both raise the odds of complications for the infant, so a positive test during pregnancy should be discussed with your obstetric provider promptly.
Prevention
- Use condoms correctly and consistently every time you have sex. This lowers, though doesn't eliminate, the risk.
- Get routine screening if you're in an at-risk group. Testing is the only way to catch the roughly 70% of infections that have no symptoms.
- Treat all partners at the same time so the parasite isn't passed back after you've been cured.
- Avoid alcohol during your treatment course to prevent the disulfiram-like reaction.
When to see a clinician
See a clinician if you have any of the symptoms above, including itching, burning, an unusual or foul-smelling discharge, or pain with urination, or if a partner has been diagnosed, even when you feel fine. Pregnant people and anyone living with HIV should be especially proactive about getting checked. Clinics handle this diagnosis daily, and it's treatable.