Trichomoniasis (trich): symptoms, causes & treatment

Author: Jessica Lloyd
Senior Vulvovaginal Specialist Naturopath | BHSc(N) | ISSVD, ISSWSH, BSSM, ATMS

Last reviewed: July 4, 2026

Trichomonas vaginalis is a tiny single-celled parasite – a protozoan, not a bacteria – that causes the sexually transmitted infection called trichomoniasis, or trich for short. It’s the most common curable STI in the world, and it’s treated with prescription antibiotics. There’s no natural cure and no way to clear it on your own: if you have trich, you need a doctor and the right tablets.^1–2

Women are far more likely than men to notice symptoms, while infected men usually feel nothing at all and pass it on without knowing. That’s a big part of why trich is so common, and why testing and treating partners matters so much.¹

The World Health Organisation estimates there are more than 150 million new cases of trich worldwide every year, and a recent global review put the overall prevalence at around 8 per cent – with roughly half of infected people having no idea they’re carrying it. Don’t let that person be you.^2–4

What is Trichomonas vaginalis?

Trichomonas vaginalis is a protozoan – a microscopic, single-celled animal that swims using whip-like tails called flagella. It isn’t a bacteria, a yeast or a virus, which is part of why it behaves differently from the other things that upset a vagina, and why it needs its own specific treatment.^1,5

In women it sets up home in the lower genital tract – the vagina, vulva and urethra. In men it tends to live quietly in the urethra. It’s passed on through sexual contact, and because it survives in moist conditions, even genital-to-genital contact without penetration can spread it.^1,5

Symptoms of trichomoniasis

Most people with trich have either no symptoms or very mild ones, which is exactly why it spreads so easily. When symptoms do show up in women, they can include:^1,5

Vaginitis – inflammation of the vulva and vagina, which may itch, burn or feel sore
Frothy, greenish-yellow discharge that can be heavier than usual
A strong, unpleasant smell that some people describe as musty or like rotting fish
Discomfort or stinging when you wee, or pain during sex
A ‘strawberry’ cervix or vagina – tiny red spots caused by inflamed, dilated blood capillaries
Men, although usually symptom-free, may notice some urethral irritation or discharge

None of these symptoms are unique to trich. Green or frothy discharge and a fishy smell can also point to bacterial vaginosis or another infection, so you can’t tell what you’ve got by symptoms alone – you have to test. If you’re trying to make sense of a sudden change, our guide to vaginal smells and what’s normal is a good place to start, and there’s an Aunt Vadge letter on green, watery discharge that walks through the same worry.

How trichomoniasis affects the vagina

Trich is an irritant. The parasite attaches to the cells lining the vagina and cervix and triggers an inflammatory response, which is what causes the soreness, the discharge and that telltale strawberry cervix.^5–6

That inflammation also disturbs the vaginal environment more broadly. A healthy vagina is acidic and dominated by protective Lactobacillus bacteria that keep the pH low and disruptive microbes in check. Trich tends to turn up alongside a disrupted, less acidic microbiome, and the two feed off each other – which is why so many people with trich also test positive for BV.⁷

This matters beyond comfort. When the protective bacteria are depleted and the vaginal lining is inflamed, your vagina’s own immune defences are weakened, and you become more vulnerable to other infections. Trich is linked to a higher risk of catching HIV, and to the cervical cell changes associated with HPV, the virus behind cervical cancer – the same pattern we see when BV raises HIV risk.^8–9 Researchers studying how the vaginal microbiome shields against STIs, including work on a ‘cervix-on-a-chip’, keep landing on the same conclusion: a Lactobacillus-rich environment is protective.

How trichomoniasis is diagnosed

You diagnose trich with a test, not a guess. Go to your doctor or a sexual health clinic and ask for an STI check. For women this usually means a vaginal swab; for men, a urethral swab or urine sample.^6,10

The most accurate option is a nucleic acid amplification test, or NAAT, which looks for the parasite’s genetic material. It picks up three to five times more infections in women than the older method of looking for moving trichomonads under a microscope (a wet mount), so it’s now the preferred test where it’s available.^8,10

A wet mount is quick and cheap and can confirm trich when the parasites are spotted, but it misses a lot of real infections, so a clear wet mount doesn’t fully rule trich out. If your symptoms persist and a basic test comes back negative, it’s worth asking about NAAT.¹⁰

How trichomoniasis is treated

Trich is treated with prescription antibiotics from the nitroimidazole family – usually metronidazole or tinidazole. These are the only treatments shown to clear the parasite, and you can’t buy an equivalent over the counter or make one at home.^11–12

For a long time a single large dose was standard. That’s changed for women: a multi-centre randomised trial found that a seven-day course of metronidazole (500 mg twice a day) roughly halved the number of women still testing positive a month later compared with a single 2 g dose. Current guidelines now recommend the seven-day course as the preferred first-line treatment for women, while men are still generally given a single 2 g dose.^11,13

A few practical things matter here:

Treat your lover(s). Trich bounces straight back if partners aren’t treated at the same time, even when they have no symptoms.¹²
Avoid sex until everyone has finished treatment and any symptoms have cleared.
Because reinfection is so common, women are advised to be retested about three months after treatment.^8,11
Some strains have become resistant to standard doses. If trich doesn’t clear, your doctor can confirm it isn’t simply reinfection and then use a higher-dose or longer regimen.^11–12

If you’re pregnant, raise trich with your maternity team rather than self-managing it, as the infection is linked to pregnancy complications and treatment decisions are made case by case.^11,14

Trichomoniasis, BV and the vaginal microbiome

The microbiome is the part of the trich story where natural and functional medicine has something useful to add – not as a treatment for the parasite, but as the context around it. Trich rarely turns up in a perfectly balanced, Lactobacillus-dominant vagina. It’s far more at home in a disrupted environment where protective bacteria have thinned out and the pH has crept up.⁷

The relationship runs both ways. A disrupted microbiome (the kind behind bacterial vaginosis) seems to make it easier for trich to take hold, and trich’s inflammation makes the microbiome worse. L. crispatus, one of the most protective species, and the lactic acid it produces are associated with resisting this kind of infection.⁷ If you want to understand which ‘type’ of microbiome you have, our piece on community state types explains the categories researchers use.

So while antibiotics are doing the actual job of clearing the parasite, the state of your microbiome is part of why trich showed up, how comfortable you feel, and how likely you are to be left with lingering BV afterwards. In our clinic we don’t treat trich itself – that’s antibiotics, and they work well – but we very often meet it in the aftermath, when someone’s microbiome has taken a hit and BV or irritation keeps cycling back.

Can natural medicine treat trich?

No – and this is worth being completely straight about. Trich is a parasite, and clearing it needs prescription antibiotics. There’s no herb, supplement, probiotic or home remedy proven to cure it, and trying to treat it yourself just gives the infection time to spread and to raise your risk of other STIs.^11–12

Researchers are studying various plant and food-derived compounds for anti-trichomonal activity, partly because drug resistance is a growing concern. But this work is almost entirely in the lab – test tubes and cell models, not real treatments you can use – and it doesn’t change the advice today: see a doctor and take the antibiotics.¹⁵

Once the parasite is cleared with treatment, natural and functional medicine does its most valuable work: rebuilding a resilient, Lactobacillus-rich microbiome so you’re less prone to the BV and irritation that so often follow, and less hospitable to infection in the first place. Think of it as working with your doctor, supporting your recovery once the infection itself has been dealt with.

What happens if trich isn’t treated?

Left untreated, trich does more than make your vagina smell terrible. In pregnancy it’s associated with premature rupture of the membranes, preterm birth and low birth weight, so it’s taken seriously by maternity teams.¹⁴

It also makes it easier to catch and pass on HIV, and it’s associated with a raised risk of the cervical cell changes that can lead to cervical cancer.^8–9 Condoms lower the risk but aren’t a guarantee, since trich can travel on a sticky finger or shared sex toys just as easily as through penetration.

It’s not only a women’s issue, either. In men, trich is usually silent but has been linked with urethral problems, and researchers have long wondered about a connection to prostate cancer. The picture there is still unsettled – a 2023 review pulling the studies together found only a small, statistically non-significant increase in risk, so it’s a question mark rather than a proven link.¹⁶ Either way, partners need testing and treatment, not just reassurance.

Preventing trich and reinfection

The most common reason trich comes back is an untreated partner, so partner treatment is prevention’s number-one rule. Condoms reduce transmission, regular STI checks catch silent infections, and avoiding sex until everyone’s treated stops the ping-pong effect.^11–12

Keeping the vaginal microbiome in good shape is the quieter half of the picture. A resilient, acidic, Lactobacillus-dominant environment is more resistant to infection generally, which is one more reason to treat recurrent BV properly rather than letting it simmer. If you and your partners share a microbiome through sex, it’s worth knowing the penis has its own microbiome too.

Frequently asked questions

Is trichomoniasis curable?

Yes. Trich is the most common curable STI, and a course of the right antibiotics clears it in most people. Cure depends on you and your partners being treated together and avoiding sex until it’s done.^1,11

Can trichomoniasis go away on its own?

Not in women. Untreated trich can hang around for months or even years, so it won’t clear without the right antibiotics. Men sometimes shake it off within a few weeks, but they can still pass it on in the meantime – which is exactly why partners are treated together.^1,11

Can I get trich without cheating or being cheated on?

Yes. Because trich often causes no symptoms, someone can carry it for months or years without knowing. A new diagnosis doesn’t automatically mean recent infidelity – it may simply have gone undetected until now.¹

How do you get trichomoniasis?

Through sexual contact with someone who’s carrying it – penis-to-vagina, vulva-to-vulva, or shared sex toys. Because the parasite lives in genital fluids, it can spread even without penetration. Non-sexual transmission through things like towels or toilet seats is possible in theory but very rare.^1,5

How long can you have trichomoniasis without knowing?

Potentially a long time. When symptoms do appear they usually show up around 5 to 28 days after exposure, but most people never get obvious symptoms and can carry trich unnoticed for months or years. That’s why testing – rather than waiting for symptoms – is how you actually find it.^1,5

Can men get trichomoniasis?

Yes, though men are usually symptom-free. They can still carry and transmit it, which is why male partners need testing and treatment even when they feel perfectly fine.^1,12

Will a Pap smear or routine swab detect trich?

Not reliably. A Pap test can occasionally flag trich, but it isn’t designed to find it. If you want to know, ask specifically for a trich test – ideally a NAAT.^8,10

Can probiotics cure trichomoniasis?

No. Probiotics and microbiome care can support a healthier vaginal environment, but they don’t clear the parasite. The infection needs antibiotics; microbiome support is for afterwards.^7,15

How soon should I be retested?

Women are generally advised to be retested around three months after treatment, because reinfection is common. You don’t need a ‘test of cure’ straight away unless symptoms persist.^8,11

What to do next

If you have symptoms or a partner has tested positive, see your doctor or a sexual health clinic and ask specifically for a trich test. Trich is treated with antibiotics, and it’s straightforward once it’s found – the hard part is finding it, because it so often hides.

If you keep cycling through discharge, smell or irritation and nothing quite adds up, a comprehensive vaginal microbiome test can give you a far clearer picture of what’s actually going on down there. And if you’d like help rebuilding your microbiome after an infection has been cleared, you’re welcome to book an appointment with us.

This is general information, not a substitute for personalised medical advice. Trichomoniasis is a sexually transmitted infection that requires diagnosis and antibiotic treatment from a doctor.