Trichomoniasis is a common sexually transmitted infection (STI) caused by a tiny parasite called Trichomonas vaginalis. Women may have soreness and itching around the vagina and a change in vaginal discharge. Trichomoniasis can be difficult to diagnose because there may not be any symptoms, and when there are symptoms, they can be similar to those of other conditions and STIs. Trichomoniasis is usually spread through unprotected sexual intercourse (without using a condom). Trichomoniasis is unlikely to go away without treatment. Most men and women are treated with an antibiotic called Metronidazole, which is very effective. Trichomoniasis rarely causes complications.

Symptoms of trichomoniasis

Trichomoniasis is believed to be very common, but many infected men and women will not have any symptoms. Women are more likely to have symptoms of trichomoniasis than men. The symptoms of trichomoniasis are similar to those of other sexually transmitted infections or conditions and they tend to appear 5 to 28 days after exposure to the infection. Trichomoniasis affects the vagina and urethra, causing any of the following symptoms:

  • Soreness, inflammation (swelling) and itching around the vagina. Sometimes your inner thighs also become itchy.
  • A change in vaginal discharge. Your discharge may appear thicker, thinner, frothy or yellow or green in colour. You may also produce more discharge than normal and it may have an unpleasant, fishy smell.
  • Pain or discomfort when passing urine.
  • Discomfort during sexual intercourse.
  • Pain in your lower abdomen (tummy).

Diagnosis of Trichomoniasis

If your GP or nurse suspects you have trichomoniasis, they will usually carry out an examination of your genital area. Trichomoniasis may cause red blotches on the walls of the vagina and on the cervix (the neck of the womb). After your physical examination, your GP or nurse may need to take a swab from either the vagina or penis so that it can be tested for the trichomoniasis infection. The swab will be sent to a laboratory for analysis. If your GP or nurse strongly suspects that you have trichomoniasis, you may be advised to begin a course of treatment before your results come back. This will ensure that your infection is treated as soon as possible and reduces the risk of the infection spreading. Sometimes, the result of a routine smear test may report that 'organisms consistent with trichomonas vaginalis have been seen'. This does not necessarily mean that you have trichomoniasis, so do not assume that you have an STI until further tests have been done. It is important that your partner(s) be notified and treated.

Treatment of Trichomoniasis

Trichomoniasis is unlikely to go away without treatment. In some rare cases, the infection may cure itself, but if you do not get treated, you risk passing the infection on to someone else. Trichomoniasis is usually treated quickly and easily. Most people will be prescribed an antibiotic known as metronidazole, which, if taken correctly, is very effective. You will usually have to take metronidazole twice a day, for five to seven days. Metronidazole can cause nausea, vomiting and a slight metallic taste in your mouth. If you cannot tolerate metronidazole, your GP may prescribe a single dose of another antibiotic called tinidazole.

Complications of Trichomoniasis

Complications are rare with trichomoniasis. The infection can sometimes weaken the barrier of mucus in the cervix (the neck of the womb). This mucus barrier helps to protect women from developing infection in their reproductive organs. If the mucus is weakened, this increases your risk of developing HIV. 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 be a low birth weight


Syphilis is a bacterial infection that causes a painless but highly infectious sore on your genitals or sometimes around the mouth. The sore lasts two to six weeks before disappearing. Secondary symptoms, such as a skin rash and sore throat, then develop. These may disappear within a few weeks, after which you have a symptom-free phase. If diagnosed early, syphilis can be easily treated with antibiotics, usually penicillin injections. But if it is left to progress untreated, syphilis can go on to cause serious conditions such as stroke, paralysis, blindness or death.