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

In women, this parasite mainly infects the vagina and urethra (the tube that carries urine out of the body; and in men, the infection generally affects the urethra, although the head of the penis or prostate gland can also become infected.

How is it spread?

The Trichomonas vaginalis parasite is usually spread by having unprotected sex (sex without a condom). It can also be spread by sharing sex toys particularly if they are not washed or covered with a new condom before use.

You do not have to have many sexual partners to catch trichomoniasis and anyone who is sexually active can catch the infection.


Symptoms of trichomoniasis usually develop within a month of infection, though up 50% of all infected men and women have no symptoms.

Symptoms in women

Trichomoniasis in women can cause any of the following symptoms:

  • abnormal vaginal discharge that may be thick, thin or frothy and yellow-green in colour
  • abnormal discharge, which may also have an unpleasant fishy smell
  • soreness, inflammation  and itching around the vagina (the inner thighs may also become itchy)
  • pain or discomfort when passing urine or having sex

Symptoms in men

Trichomoniasis in men can cause any of the following symptoms:

  • pain during urination or ejaculation
  • frequent need to urinate
  • thin white discharge from the penis
  • soreness, swelling and redness around the head of the penis (balanitis) or foreskin (balano-posthitis)

Trichomoniasis is not passed on through:

  • oral or anal sex
  • kissing or hugging
  • sharing cups, plates or cutlery
  • toilet seats


Trichomoniasis can sometimes be difficult to diagnose as the symptoms are similar to those of other sexually transmitted infections (STIs). If you think you may have trichomoniasis, please contact your GP or the Infection Prevention Team at the GHA.

If your doctor or nurse suspects you have trichomoniasis, they will carry out an examination of your genital area.

They may need to take a swab from either the vagina or penis, which will be analysed in a laboratory to check for signs of the trichomoniasis infection. It may take several days for the results to come back. In men, a urine sample can also be tested for trichomoniasis.

If your doctor or nurse strongly suspects that you do have trichomoniasis, you may be given a course of treatment before your test results come back. This is to ensure that your infection is treated as soon as possible and reduce the risk of it spreading.


The best way to prevent trichomoniasis is to have safe sex (i.e. always using a condom when having sex, covering any sex toys you use with a condom, and washing sex toys after use).

Remember: If you have had trichomoniasis and it has been treated, you will not be immune to the infection and could get it again.


Trichomoniasis can be effectively treated with antibiotics. It is important that you complete the whole course of antibiotics and avoid having sex until the infection clears up so as to prevent reinfection. Your current sexual partner and any other recent partners should also be treated.

If you take your antibiotics correctly, you will not necessarily need any follow-up tests or examinations for trichomoniasis. However, if your symptoms remain or recur after treatment, you may need further testing to see whether your symptoms are being caused by a different sexually transmitted infection (STI).

If you have unprotected sex before your treatment is finished you may become re-infected. In this instance, it is advisable that you consult with your GP or nurse. You may also need medical advice if you:

a) have not completed your course of antibiotics

b) did not take your antibiotics correctly

c) vomited shortly after taking your antibiotics