Trichomonas vaginalis

Trichomoniasis is a sexually transmitted infection (STI) caused by a tiny parasite called Trichomonas vaginalis (TV).

Symptoms of trichomoniasis usually develop within a month of infection, although up to half of all infected men and women have no symptoms.

In women, trichomoniasis can cause soreness and itching around the vagina and a change in vaginal discharge. Infected men may experience pain during urination and a thin white discharge from the penis.

Read more about the symptoms of trichomoniasis.

When to seek medical advice

Visit your GP or local genitourinary medicine (GUM) clinic if you experience any of the symptoms of trichomoniasis or if you think you may be infected.

Trichomoniasis can usually be diagnosed after an examination of your genital area and a laboratory test carried out on a swab taken from the vagina or penis.

If the test shows that you have trichomoniasis, it is important that your current sexual partner and any other recent partners are also tested and treated.

Read more about diagnosing trichomoniasis.

What causes trichomoniasis?

Trichomoniasis is caused by a tiny single-celled parasite (an organism that lives off another living being) called Trichomonas vaginalis.

In women, this parasite mainly infects the vagina and urethra (the tube that carries urine out of the body). In men, the infection most commonly affects the urethra, but the head of the penis or prostate gland (a gland near the bladder that helps produce semen) can become infected in some cases.

The parasite is usually spread by having unprotected sex (without using a condom), although it can also be spread by sharing sex toys. You do not have to have many sexual partners to catch trichomoniasis. Anyone who is sexually active can catch it and pass it on.

Trichomoniasis cannot be passed on through oral or anal sex, kissing, hugging, sharing cups, plates or cutlery, toilet seats or towels.

The best way to prevent trichomoniasis is to have safer sex. This means always using a condom when having sex, covering any sex toys you use with a condom, and washing sex toys after use.

Read more about preventing trichomoniasis.

Treating trichomoniasis

Trichomoniasis is unlikely to go away without treatment, but it can be effectively treated with antibiotics. Most men and women are treated with an antibiotic called metronidazole, which is usually taken twice a day for five to seven days.

It is important to complete the whole course of antibiotics and avoid having sex until the infection clears up to prevent reinfection.

Your current sexual partner and any other recent partners should also be treated.

Read more about treating trichomoniasis.

Complications of trichomoniasis

Complications of trichomoniasis are rare, although some women with the infection may be at an increased risk of further problems.

If any STI is left untreated, including trichomoniasis, this may make it easier for you to become infected with other STIs, including HIV.

If you develop trichomoniasis while you are pregnant, the infection may cause your baby to be born prematurely (before the 37th week of pregnancy) or have a low birth weight.