Trichomoniasis complications happen when an untreated Trichomonas vaginalis infection inflames the genital tract. In women that inflammation can spread upward and contribute to pelvic inflammatory disease and pregnancy problems; in men it can drive prostatitis and epididymitis. Active infection also raises the risk of acquiring and transmitting HIV. Treatment clears the parasite and reverses the risk.
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 |
The essentials: what trichomoniasis can do if left alone
Trichomoniasis is caused by a single-celled protozoan parasite, Trichomonas vaginalis, and it's the most common curable non-viral STI in the US — an estimated 2.6 million infections at any given time, landing disproportionately on women, who account for over 80% of cases Sex Transm Dis, 2018. The same biology that makes it easy to miss also lets it linger and inflame tissue for months.
About 70% of infected people have no signs or symptoms at all CDC. A silent infection isn't harmless; it's one you don't know to treat. The longer the parasite irritates the vaginal lining or the male urethra and prostate, the more it disrupts the local defenses that normally keep other pathogens out. If you're wondering how long an infection can sit unnoticed, see how long can trichomoniasis go undetected?.
The complications fall into three buckets: upper-tract and pregnancy problems in women, prostate and fertility problems in men, and for everyone a measurable increase in HIV risk.
HIV acquisition and transmission
This is the complication most people have never heard of, and the most consequential. The inflammation trichomoniasis causes recruits immune cells to the genital surface and can produce tiny breaks in the mucosa. Those changes give HIV more target cells and easier entry, so active trichomoniasis raises the risk of getting HIV if you're exposed. In someone who already has HIV, it raises the amount of virus shed in genital fluids, making onward transmission more likely. Clearing trich removes that amplifier.
Pelvic and pregnancy complications in women
In women the parasite lives in the vagina and urethra, and the persistent inflammation can extend the irritation upward. Trichomoniasis is associated with pelvic inflammatory disease (PID — infection of the uterus, fallopian tubes and surrounding tissue that can scar the tubes and threaten fertility), particularly in women who also have HIV. During pregnancy it's linked to preterm birth (delivering early, before the baby is fully developed) and low birth weight, and a baby can rarely be exposed at delivery. Screening matters during prenatal care for these reasons.
Prostatitis and male infertility
Men are commonly asymptomatic, which lets the parasite persist in the urethra and prostate. There it's associated with prostatitis (inflammation of the prostate gland, causing pelvic or perineal discomfort and urinary symptoms) and epididymitis (inflammation of the coiled tube behind the testicle that stores sperm). Both processes can impair sperm quality and have been tied to subfertility, a male complication that rarely gets discussed alongside the female ones.
What the symptoms actually feel like
Because most infections are silent, symptoms — when they show — are your cue to test, not a reliable warning system. In women, the classic picture is itching, burning, redness or soreness of the genitals, discomfort while urinating, and a clear, white, yellowish or greenish discharge that often has a fishy smell. In men, signs are subtler: itching or irritation inside the penis, burning after urinating or ejaculating, and sometimes discharge.
None of these are specific to trich. They overlap heavily with bacterial vaginosis, yeast, gonorrhea and chlamydia, so you can't diagnose it by symptoms, and testing is the only way to know.
Testing: how clinicians confirm it
The preferred test is a nucleic acid amplification test (NAAT), such as the Aptima T. vaginalis assay, which detects the parasite's genetic material with a sensitivity of about 95–100% — far more reliable than looking at a sample under the microscope, which misses many infections CDC STI Tx Guidelines, 2021. Specimens include a vaginal swab or a female urine sample.
In practice, testing is undramatic: most cases are diagnosed from a simple 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. For the full walkthrough of methods and accuracy, see trichomoniasis testing & diagnosis, and if you're timing a test around a possible exposure, read when to test after exposure. Ready to start? You can get tested now.
Treatment: a defined course that cures it
Trichomoniasis is curable with antibiotics in the nitroimidazole family. The recommended regimen for women is metronidazole 500 mg orally twice daily for 7 days; for men it's metronidazole 2 g orally as a single dose; tinidazole 2 g orally as a single dose is an alternative for either.
The shift for women is worth understanding. Guidelines moved women off the old single 2 g dose because the multi-day course works better. 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 — roughly halving the retest-positive rate Muzny et al.. The multi-day course is now preferred for women.
A few practical rules make or break a cure. Finish every dose even once you feel better. Don't drink alcohol during metronidazole or tinidazole, or for a short window afterward — combining them causes a disulfiram-like reaction (flushing, nausea, vomiting, racing heart). Treat all sex partners at the same time, because reinfection is common when one partner is missed, and avoid sex until everyone has completed treatment. The full regimen details live in our guide to trichomoniasis treatment.
Because reinfection is so common, sexually active women should be retested about 3 months after treatment. This catches a new infection picked up from an untreated partner rather than the original cure.
Complication risk: treated vs untreated
| Concern | Untreated infection | After completing treatment |
|---|---|---|
| HIV acquisition/transmission | Inflammation raises risk | Risk amplifier removed |
| Women: PID & pregnancy | Linked to PID, preterm birth, low birth weight | Parasite cleared, inflammation resolves |
| Men: prostate & fertility | Linked to prostatitis, epididymitis | Inflammation resolves |
| Passing it on | Ongoing while infected | Stops once you and partners are cured |
Prevention that actually lowers your risk
- Use condoms correctly and consistently, every time, which lowers the risk of trichomoniasis and other sexually transmitted infections.
- Get routine STI testing if you're sexually active, since most trich infections have no symptoms and screening is the only way to catch them.
- Make sure every sex partner is tested and treated before resuming sex, so you don't pass the parasite back and forth.
- Skip alcohol for the full treatment course to avoid the metronidazole reaction.
A diagnosis here is common and treatable; clinics handle it daily, and it says nothing about you as a person. Prevention keeps inflammation and HIV risk off the table.
When to see a clinician
See a clinician if you have any of the symptoms above, if a partner tells you they tested positive, if you're pregnant and haven't been screened, or if symptoms persist after you've finished treatment. Persistent symptoms can mean reinfection from an untreated partner or, less often, a strain that needs a different regimen. Both are fixable once you're back in the clinic.