Trichomonas (trichomoniasis): symptoms, testing and treatment

Trichomonas (also called TV, trichomoniasis or trich) is a common non-viral sexually transmitted infection caused by a tiny organism called Trichomonas vaginalis, according to Terrence Higgins Trust. It can infect the vagina, the urethra (the tube urine leaves through) or the area under the foreskin of the penis.

The NHS says it is passed on through vaginal sex or sharing sex toys and can cause serious problems if untreated. Skin-to-skin contact of the genital area can also pass it on. Terrence Higgins Trust says it is not passed on through anal sex, oral sex, kissing, hugging or general body contact, and that you do not need many partners to get it: anyone who is sexually active can. Unlike most STIs it is commoner in people over the age of 25.

The NHS notes the main symptoms are a yellow-green vaginal discharge that may smell like fish and pain when peeing, and that many people get no symptoms at all, so testing matters if you think you might have it. Terrence Higgins Trust adds that the symptoms resemble those of many other STIs, which can make diagnosis hard without a test.

The NHS advises going to a sexual health clinic or seeing a GP if you or a partner have symptoms, if you have had sex without a condom with a new partner or someone with an STI, or if you are pregnant or planning to become pregnant and think you might have trichomoniasis. A doctor or nurse will ask about your symptoms and sexual partners and may examine you.

The test uses a swab, like a large cotton bud, to take fluid from the vagina or penis, and you may be able to do the swab yourself. You might also give a urine sample. You can ask for a test even without symptoms, and tests for other STIs are often done at the same time. If you would like a chaperone, tell the clinic when booking. Terrence Higgins Trust says you can also test through an online service, which may charge.

Trichomoniasis is treated with antibiotics, usually metronidazole. The NHS says you take it twice a day for 7 days or as a one-off dose, with symptoms usually starting to improve within a few days, and the course should be finished even if you feel better. A further course may be given if symptoms do not go away. Terrence Higgins Trust says the single large dose may carry a higher risk of side effects and is not recommended as a precaution for pregnant or breastfeeding women, and that the standard seven-day course is safe in pregnancy and while breastfeeding.

An important safety point from Terrence Higgins Trust is that you cannot drink alcohol while taking metronidazole and for at least 24 to 48 hours after completing treatment. Read the leaflet that comes with the medicine and ask the clinic or a pharmacist if unsure.

Do not have sex until at least 1 week after you and any sexual partners have finished treatment, even with a condom according to Terrence Higgins Trust, to avoid reinfection. You can catch it again if you have had it before.

The NHS says your current and any recent sexual partners will also need to be treated, and that the GP or sexual health clinic can advise you about contacting them, which can be done without naming you. If partners are not treated, you may be re-infected after your own treatment.

Reduce the chance of passing it on by using external or internal condoms, covering shared sex toys with a new condom each time or washing them between uses, and getting tested once a year or when you have a new partner, as the NHS suggests. Terrence Higgins Trust says hormonal contraception and HIV PrEP do not protect against STIs.

The NHS lists complications if trichomoniasis is not treated: a higher chance of getting or passing on HIV, a higher chance of bacterial vaginosis, pelvic inflammatory disease (which can lead to pelvic pain, ectopic pregnancy or infertility) and prostate inflammation. In pregnancy it can cause a baby to be born early or with a low birthweight, it can be passed to the baby at birth, and the chance of sepsis after birth is higher.

Terrence Higgins Trust notes that if you have trichomonas and are exposed to HIV, you may be more likely to become infected, but that people on effective HIV treatment with an undetectable viral load cannot pass on HIV even if they have trichomonas.

NHS sexual health clinics are the usual route, and Terrence Higgins Trust says you can be tested for trichomonas at a sexual health clinic. GPs can also see you, as the NHS advises, and the NHS says treatment is with antibiotics prescribed after diagnosis.

Private clinics and online testing services also exist. If you use one, check it is regulated, ask which tests are included, make sure you have a clear plan for treatment and partner notification, and ask for results to be shared with your GP if you want them to be. Do not buy antibiotics without a prescription.