Men get trichomoniasis through sexual contact with an infected partner. The infection is caused by a microscopic parasite called Trichomonas vaginalis, which passes between people during vaginal sex. In men, the parasite typically infects the urethra, the tube inside the penis that carries urine and semen. About 70% of people with trichomoniasis have no symptoms at all, which means many men contract it without either partner realizing anything is wrong.
How the Parasite Spreads
Trichomoniasis spreads through genital-to-genital contact during vaginal intercourse. The parasite lives in the lower genital tract and moves from one person to another through the exchange of genital fluids during sex. In men, it colonizes the urethra, and in some cases the prostate gland.
A few important details about how transmission works. The parasite does not spread through casual contact like hugging, sharing food, or using the same toilet seat. It is not transmitted through oral or anal sex. A man can catch trichomoniasis from a female partner who has no visible symptoms, and he can pass it along the same way. Both partners need treatment at the same time, or they will keep reinfecting each other.
Why Most Men Don’t Notice It
The majority of men with trichomoniasis never develop symptoms. When symptoms do appear, they typically show up between 5 and 28 days after exposure. Men who do have symptoms may notice itching or irritation inside the penis, a burning sensation after urinating or ejaculating, or an unusual discharge from the penis.
These symptoms can be mild enough that men dismiss them or assume they’re caused by something else entirely. The infection can also clear on its own in some men, but this is unpredictable and doesn’t happen reliably. In the meantime, an infected man remains contagious regardless of whether he has symptoms.
Risks of Leaving It Untreated
Because trichomoniasis often flies under the radar in men, it can persist for weeks or months without treatment. Over time, an untreated infection can lead to chronic prostatitis (ongoing swelling and irritation of the prostate gland), discomfort during urination or ejaculation that doesn’t resolve, and in some cases, infertility. The infection also increases susceptibility to other sexually transmitted infections, including HIV, by causing low-level inflammation in the genital tract.
How Men Get Tested
Testing for trichomoniasis in men usually starts with either a urethral swab or a urine sample. The simplest initial test is called wet prep microscopy, where a lab technician examines the sample under a microscope looking for the parasite. This test is quick and inexpensive, but it isn’t always accurate, especially in men, because parasite numbers in the male urethra tend to be lower than in the female genital tract.
If the microscopy comes back negative but trichomoniasis is still suspected, a more sensitive test called a nucleic acid amplification test (NAAT) can detect genetic material from the parasite even when numbers are very low. This is the most reliable option. In some cases, trichomoniasis is discovered incidentally when a urine sample is being tested for something else, like a urinary tract infection or chlamydia.
One challenge is that routine STI screenings don’t always include trichomoniasis. If you think you’ve been exposed or a partner has been diagnosed, you may need to specifically ask for this test.
How It’s Treated
Trichomoniasis is curable with a single dose of an antibiotic taken by mouth. The standard treatment for men is a one-time oral dose, and most people are cleared of the infection within a week. An alternative medication exists for people who can’t tolerate the first option. You should avoid alcohol for at least 24 hours after treatment, as mixing the two can cause nausea and vomiting.
Both sexual partners need to be treated simultaneously. If only one person takes the medication, the untreated partner will reinfect the other the next time they have sex. It’s recommended to wait at least seven days after treatment before having sex again, even if symptoms have already resolved, to ensure the parasite is fully eliminated.
Reducing Your Risk
Condoms significantly reduce the risk of trichomoniasis transmission, though they don’t eliminate it entirely because the parasite can be present on skin not covered by the condom. Having fewer sexual partners lowers your overall exposure risk. If a partner is diagnosed, getting tested yourself is important even if you feel completely fine, since the absence of symptoms is the norm rather than the exception for men with this infection.