It is caused by a parasite. It passes between people during sex.

Risk Factors

It is more common in women than men. The risk may be higher for those who:

  • Have many sex partners
  • Do not use condoms with sex
  • Have had STIs before



The infection does not always cause symptoms. When they happen, they may be:

In women:

  • A bad-smelling, greenish-yellow discharge from the vagina
  • Pain, itching, or burning of the genitals
  • Bleeding after sex
Infection Site in Women
Copyright © Nucleus Medical Media, Inc.

In men:

  • Discharge from the penis
  • Itching or pain
  • Pain when passing urine
  • Pain in the testes or scrotum
Infection Site in Men
Male Urethtra
Copyright © Nucleus Medical Media, Inc.


The doctor will ask about your symptoms, and sexual and health history. A physical exam will be done. It will focus on the pelvic area.

Testing involves:

  • Women—testing fluid or discharge from the vagina
  • Men—testing urine, semen, or discharge from the penis

A lab will check the samples for the parasite.



The infection is treated with antibiotics. Sex partners may also need treatment.


The risk of STIs is reduced by:

  • Always using condoms during sex
  • Only having sex with one person

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.