Overview

Trichomoniasis is a sexually transmitted infection caused by a parasite. In women, trichomoniasis can cause a foul-smelling vaginal discharge, genital itching and painful urination. Men who have trichomoniasis typically have no symptoms. Pregnant women who have trichomoniasis may be at higher risk of delivering their babies prematurely.

To prevent reinfection with the organism that causes trichomoniasis, both partners should be treated. The most common treatment for trichomoniasis involves taking one megadose of metronidazole (Flagyl, Tindamax). You can reduce your risk of infection by using condoms correctly every time you have sex.

Symptoms

Many women and most men with trichomoniasis have no symptoms, at least not at first. Trichomoniasis signs and symptoms for women include:

  • A profuse and often foul-smelling vaginal discharge — which may be white, gray, yellow or green
  • Genital redness, burning and itching
  • Pain with urination or sexual intercourse

Trichomoniasis rarely causes symptoms in men. When men do have signs and symptoms, however, they may include:

  • Irritation inside the penis
  • Burning with urination or after ejaculation
  • Discharge from the penis

When to see a doctor

See your doctor if you have a foul-smelling vaginal discharge or if you experience pain with urination or sexual intercourse.

Causes

Trichomoniasis is caused by a one-celled protozoan, a type of tiny parasite that travels between people during sexual intercourse. The incubation period between exposure and infection is unknown, but it's thought to range from five to 28 days.

Risk factors

Risk factors include having:

  • Multiple sexual partners
  • A history of other sexually transmitted infections
  • A previous episode of trichomoniasis
  • Having sex without a condom

Complications

Pregnant women who have trichomoniasis may:

  • Deliver prematurely
  • Have a baby with a low birth weight
  • Transmit the infection to the baby as he or she passes through the birth canal

Having trichomoniasis also appears to make it easier for women to become infected with HIV, the virus that causes AIDS.

Prevention

As with other sexually transmitted infections, the only way to prevent trichomoniasis is to abstain from sex. To lower your risk, use condoms correctly every time you have sex.

March 21, 2015
References
  1. Sobel JD. Trichomoniasis. http://www.uptodate.com/home. Accessed Jan. 23, 2015.
  2. Trichomoniasis fact sheet. Centers for Disease Control and Prevention. http://www.cdc.gov/STD/Trichomonas/STDFact-Trichomoniasis.htm. Accessed Jan. 23, 2015.
  3. Hobbs MM, et al. Modern diagnosis of trichomonas vaginalis infection. Sexually Transmitted Infections. 2013;89:434.