NHS Choices - Introduction
Trichomoniasis is a common sexually transmitted infection (STI) caused by a tiny parasite called Trichomonas vaginalis.
Women are more likely to have symptoms than men. They may have soreness and itching around the vagina and a change in vaginal discharge, while men may experience pain after urination and ejaculation.
See your GP if you experience any of the symptoms of trichomoniasis or if you know you’ve been exposed to it.
If you do not want to see your GP, go to your local genitourinary medicine (GUM) clinic, where they will be able to test and treat your infection. Find your nearest sexual health clinic.
What causes trichomoniasis?
Trichomoniasis is caused by a tiny single-celled parasite (lives off another living being) called Trichomonas vaginalis. It is a single-celled organism that latches onto the lining of the vagina.
The parasite is usually spread by having unprotected sex (without using a condom). 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.
In rare cases, the infection can be spread by sharing sex toys. However, using a condom to cover your sex toy and washing it after use should decrease the chances of the infection spreading.
Trichomoniasis is unlikely to go away without treatment. Most men and women are treated with an antibiotic called metronidazole, which is very effective. People who cannot take metronidazole may be prescribed a different medication.
It is important to complete the whole course of antibiotics and avoid sexual intercourse until the infection clears up to prevent reinfection.
Read more information about treating trichomoniasis.
Complications of trichomoniasis
Complications are rare with trichomoniasis.
However, the infection can sometimes weaken the barrier of mucus in the cervix (the neck of the womb). This mucus barrier helps protect women from developing infection in their reproductive organs. If the mucus is weakened, this increases your risk of developing HIV.
It is therefore very important to practise safe sex by always using a condom.
Read more information about preventing trichomoniasis.
If you develop trichomoniasis while you are pregnant, your baby may be at risk of developing complications. Trichomoniasis may cause your baby to be born prematurely, or to have a low birth weight.