Trichomoniasis is a sexually transmitted infection that in women 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 are at higher risk of delivering 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). You can reduce your risk of infection by using condoms correctly every time you have sex.


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

Signs and symptoms may worsen during menstruation. But some women who have trichomoniasis don’t have any symptoms. Men who have trichomoniasis rarely exhibit symptoms, but when they do, it’s usually painful urination.

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.


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 can range from five to 28 days.

Risk factors

Risk factors include:

  • Having multiple sexual partners
  • History of other sexually transmitted diseases
  • Previous episode of trichomoniasis


Pregnant women who have trichomoniasis may:

  • Deliver prematurely
  • Have a baby with a low birth weight
  • Transmit the infection to the baby as it 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.

Preparing for your appointment

Your family doctor, gynecologist or a medical practitioner at an urgent care center can diagnose and prescribe treatment for trichomoniasis.

What you can do

Before the appointment, you might want to prepare a list that includes:

  • A detailed description of your symptoms, including when they started
  • Any sexually transmitted infections you’ve had
  • The number of sexual partners you’ve had during the past few years

What to expect from your doctor

Your doctor will perform a pelvic exam and may take a sample of your vaginal fluids for testing.

Tests and diagnosis

The diagnosis of trichomoniasis can be confirmed by looking at a sample of vaginal fluid for women or urine for men under a microscope. Growing a culture from the fluid may be better at detecting trichomoniasis, and newer tests, known as rapid antigen tests and nucleic acid amplification, may be even better.

Treatments and drugs

The most common treatment for trichomoniasis, including if you’re pregnant, is to swallow one megadose of either metronidazole (Flagyl) or tinidazole (Tindamax). Taking the medication by mouth is much more effective for trichomoniasis than inserting a cream or gel version of the medication into the vagina.

Both you and your partner need treatment and to avoid unprotected sex until the infection is cured, which takes about a week.

Side effects of the medication may include:

  • Nausea
  • Vomiting
  • Headache
  • Metallic taste
  • Dizziness

Don’t drink alcohol for 24 hours after taking metronidazole or 72 hours after taking tinidazole, because it can cause severe nausea and vomiting.


The method of preventing trichomoniasis is the same as those for preventing other sexually transmitted infections — abstain from sex. To lower your risk, use condoms correctly every time you have sex.