Trichomoniasis Fact Sheet

Updated August 2025

Definition

Trichomoniasis is a common sexually transmitted infection (STI) caused by the parasite Trichomonas vaginalis.

Signs and Symptoms

It is common not to notice any symptoms. If symptoms do occur, they usually appear 5 to 28 days after being infected but sometimes it can take much longer.

Symptoms in men can include penile discharge, burning when urinating or after sex, and/or irritation or redness at the tip of the penis.

Women are more likely than men to get symptoms. Symptoms can include vaginal itching and irritation, pain during sex or when urinating, and a foul-smelling white, yellow or greenish vaginal discharge.

Tests

Urine samples can be sent for testing from both men and women. For women, a sample of fluid from the vagina or cervix can also be collected for testing. For men, urethral swabs can also be tested.

Complications (that may arise)

In rare cases, trichomoniasis can cause pelvic inflammatory disease (PID) in women, which can lead to infertility, chronic pelvic pain or ectopic pregnancy. If a pregnant woman is infected, it may cause the baby to be born early or with a low birth weight.

In men, trichomoniasis can cause infertility, discomfort after urination or ejaculation or chronic prostatitis (swelling and irritation of prostate gland).

Risk Factors

People who have multiple sexual partners are more likely to become exposed to and infected with trichomoniasis. Unprotected sex can also increase the risk of infection.

Treatment

The most effective treatment for trichomoniasis is an antibiotic called metronidazole. Some people may feel nauseated or have diarrhea when taking this medication, while others may notice a dry metallic or bitter taste in their mouth. You should not drink any alcohol (beer, wine or liquor) during treatment and for 24 hours afterwards. Alcohol and metronidazole can cause severe nausea and vomiting.

If you are pregnant or breastfeeding, talk to your health care provider before taking any medication.

Self-care

Here are a few important points to remember:

  • Take all medication as prescribed by your health care provider or clinic.
  • It is important not to have sex during treatment and for 7 days after you and your sexual partner(s) have been treated. A person can get re-infected every time they have sex with an infected partner who has not been treated.
  • If you have an untreated STI like trichomoniasis, it is easier to get HIV from a person who has it or to pass HIV to another person.
  • It is possible to have more than one infection at a time, so it is important to be tested for other STIs and HIV.
  • Use condoms correctly every time you have sex to lower your chance of getting an STI, including HIV.

Transmission/Spread

Trichomoniasis is most often spread through unprotected vaginal intercourse (penis to vagina, vagina to penis or vagina to vagina) or sharing sex toys with an infected partner.

Information for Sexual Partners (for STIs)

All sexual partner(s) need treatment to prevent re-infection. Do not have sex while you and your partner are on the medication and for 7 days after you both finish. If you use sex toys do not share them and follow the instructions on how to clean them properly.

For More Information

Call the Sexual Health Infoline Ontario at 416-392-2437 or 1-800-668-2437 or visit toronto.ca/health

Safer sex: To reduce your risk of getting a sexually transmitted infection (STI), use a condom every time you have vaginal, anal or oral sex.