Trichomoniasis

The most distinctive trichomoniasis discharge is frothy, yellow-green or gray-green, and often has a strong, unpleasant fishy or musty odor. The 'frothy' quality, small bubbles throughout, is caused by gas produced by the parasite and is more characteristic of trichomoniasis than of other vaginal infections. That said, about 70% of infected women have no discharge at all, and when discharge is present it can look much more ordinary: thinner, whiter, or less obviously abnormal. A normal-appearing discharge never rules out trichomoniasis, which is why a NAAT test is the only reliable way to know.

Yes. Men can and do get trichomoniasis, the parasite infects the urethra and can persist there for weeks. The difference is that men are far more likely to be completely asymptomatic, and many men's immune systems clear the infection spontaneously over several weeks. But 'cleared' is not the same as 'not infectious': men can transmit the parasite to partners throughout the period before clearance, and some men carry it long-term without any symptoms. Because men rarely develop symptoms, they are rarely tested, which is one reason trichomoniasis circulates so persistently. When symptoms do occur in men, they include mild urethral irritation, discharge, or burning after ejaculation.

Potentially for months or years. Because roughly 70% of infected people have no symptoms at all, and because symptoms that do appear can come and go unpredictably, trichomoniasis can persist undetected for very long periods. There is no set timeline at which the infection becomes obvious: some people carry it for years, passing it to multiple partners, without ever having a symptom that prompts testing. This is precisely why a specific trichomoniasis test, not just a symptom check, is the only reliable way to know your status, especially if you have never been specifically tested for trich.

Yes: trichomoniasis is completely curable with metronidazole (the CDC recommends 500 mg twice daily for 7 days for women, a single 2g dose for men) or tinidazole 2g, and cure rates exceed 95% when both partners are treated simultaneously. There is no persistent infection after successful treatment, no latent stage, and no carrier state. The critical catch is that trichomoniasis produces no lasting immunity, you can be re-infected immediately after clearance if your partner has not been treated. Treating yourself without treating your partner is not a cure; it is a temporary interruption of the cycle. Both partners must be treated at the same time for the cure to hold.

With the recommended regimen (metronidazole 500 mg twice daily for 7 days for women, a single 2g dose for men, or tinidazole 2g once), the antibiotic reaches effective levels and the parasite is typically cleared within several days. The CDC recommends avoiding sex for 7 days after treatment, and until all partners have also completed treatment, to allow full clearance and prevent the re-infection that would start the cycle over. Do not assume you are clear just because symptoms resolve before 7 days; symptoms can improve before parasitic clearance is complete. If symptoms persist beyond 7–10 days after treatment, re-evaluation and a follow-up NAAT are needed.

Yes, re-infection is extremely common and is the primary reason trichomoniasis appears to 'come back' after treatment. Trichomoniasis produces no lasting immunity, so a successfully treated person is fully susceptible immediately after clearance. If a partner was not treated at the same time, or if a new partner carries the infection, re-infection can occur on the very next sexual encounter. This is why the CDC recommends retesting 3 months after treatment regardless of symptoms, most re-infections are completely silent and would otherwise go undetected. True treatment failure from drug resistance is rare (estimated 2–5%), far less common than re-infection.

Rarely, and unpredictably. In men, the immune system does often clear the infection within weeks, but this is not reliable and cannot be assumed. In women, spontaneous clearance is less common, and the infection tends to persist for months to years without treatment. Even when symptoms come and go, which they can do without treatment, the infection is still present and still transmissible. Waiting for trichomoniasis to resolve on its own is not a safe strategy: you remain infectious to partners throughout, and the HIV risk, pregnancy risks, and inflammation associated with the infection continue. A short antibiotic course cures it reliably, there is no clinical reason to wait.

Almost certainly not. Trichomonas vaginalis is transmitted through direct genital-to-genital contact, penis-to-vagina or vulva-to-vulva, and the parasite cannot survive more than a few minutes outside the warm, moist environment of the genitourinary tract. Transmission via toilet seats, shared towels, bath water, or other fomites is theoretically possible but has never been demonstrated to occur in practice. If you test positive and believe you have not had sexual contact, the far more likely explanations are asymptomatic infection from a past partner that was never detected, or that a current partner has had other exposures. Trichomoniasis is, in practical terms, sexually transmitted.

Yes, significantly. Active trichomoniasis doubles the risk of HIV acquisition in women. The mechanism is direct and well-characterized: the parasite causes genital epithelial disruption and recruits an inflammatory cellular response that floods the mucosal surface with CD4+ T cells, the exact cells HIV targets. This creates both a physical breach in the mucosal barrier and an abundance of HIV target cells at the exposure site. In people already living with HIV, trichomoniasis increases HIV concentration in cervicovaginal secretions and semen, making onward transmission to uninfected partners more likely. The CDC recommendation for annual trichomoniasis screening in all people living with HIV is based directly on this bidirectional interaction.

Yes: trichomoniasis in pregnancy is associated with preterm labor, premature rupture of membranes, and low birth weight. These outcomes are thought to result from the inflammatory response the parasite triggers in the lower genital tract. Metronidazole is safe to use throughout pregnancy and is the recommended treatment. Tinidazole, the alternative, is not recommended in pregnancy due to limited safety data. The decision about whether to treat asymptomatic trichomoniasis in pregnancy specifically to prevent preterm birth is more nuanced, the evidence is mixed, but symptomatic trichomoniasis in pregnancy should always be treated promptly. Discuss your specific situation with your OB or midwife.

No, they are entirely different infections requiring completely different treatments. A vaginal yeast infection is caused by a fungus (usually Candida albicans) and is treated with antifungal medications (fluconazole or topical azoles). Trichomoniasis is caused by a protozoan parasite and is treated with metronidazole or tinidazole, which have no antifungal activity. The symptoms can overlap significantly: both can cause vaginal itching, burning, and abnormal discharge. However, trichomoniasis discharge is classically frothy and yellow-green with a fishy odor, while yeast discharge is typically thick, white, and odorless (cottage-cheese-like) with more prominent itching. Self-treating with OTC yeast medication when you actually have trichomoniasis delays the correct diagnosis, leaves you infectious to partners, and maintains the HIV risk. A test is the only way to be certain.

Yes, this is non-negotiable for an actual cure. Trichomoniasis produces no lasting immunity; you can be re-infected immediately after clearance if your partner has not been treated. Because most infected partners have no symptoms, they will not know they carry the infection without testing, and they will re-infect you on the next sexual encounter. Both (or all current) partners should ideally be treated on the same day, before any sexual contact resumes. Some clinics now offer 'expedited partner therapy', providing treatment for a partner without requiring them to come in for testing first, specifically to maximize same-day simultaneous treatment. Avoid sex for 7 days after all partners have completed treatment.

No. This is an important distinction from other STIs. Trichomonas vaginalis does not infect mucosal surfaces of the throat, rectum, or anus: only the lower genitourinary tract (vagina, vulva, cervix, and urethra). This means trichomoniasis cannot be transmitted through oral sex or anal sex, and throat or rectal swabs will not detect it. If you have throat or rectal symptoms after sexual exposure, other infections, chlamydia, gonorrhea, herpes, are far more likely culprits and require different testing. Trichomoniasis testing is warranted for the genitourinary tract only.