Trichomoniasis is a common 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 might be at higher risk of delivering their babies prematurely.

Treatment for trichomoniasis is taking an antibiotic — either metronidazole (Flagyl), tinidazole (Tindamax) or secnidazole (Solosec). To prevent being infected again, all sexual partners should be treated at the same time. You can reduce your risk of infection by using condoms correctly every time you have sex.


Most people with trichomoniasis have no signs or symptoms. However, symptoms may develop over time. When signs and symptoms develop, they are different for men and women.

In women, trichomoniasis signs and symptoms include:

  • A large amount of a thin, often foul-smelling discharge from the vagina — which might be clear, white, gray, yellow or green
  • Genital redness, burning and itching
  • Pain with urination or sex
  • Discomfort over the lower stomach area

In men, trichomoniasis rarely causes symptoms. When men do have signs and symptoms, however, they might include:

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

When to see a doctor

See your health care provider if you have any symptoms of trichomoniasis or if you become aware that a sexual partner has the infection.


Trichomoniasis is caused by a one-celled protozoan, a type of tiny parasite called Trichomonas vaginalis. The parasite passes between people during genital contact, including vaginal, oral or anal sex. The infection can be passed between men and women, women, and sometimes men.

The parasite infects the lower genital tract. In women, this includes the outer part of the genitals (vulva), vagina, opening of the uterus (cervix) and the urinary opening (urethra). In men, the parasite infects the inside of the penis (urethra).

The time between exposure to the parasite and infection (incubation period) is unknown. But it's thought to range from four to 28 days. Even without symptoms, you or your partner can still spread the infection.

Risk factors

Risk factors for getting trichomoniasis include having:

  • Multiple sexual partners
  • A history of other sexually transmitted infections (STIs)
  • A previous episode of trichomoniasis
  • Sex without a condom


Pregnant women who have trichomoniasis might:

  • Deliver too early (prematurely)
  • Have a baby with a low birth weight
  • Give the infection to the baby as the baby passes through the birth canal

Having trichomoniasis causes irritation in the genital area that may make it easier for other sexually transmitted infections (STIs) to enter the body or to pass them to others. Trichomoniasis also appears to make it easier to become infected with human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS).

Trichomoniasis is associated with an increased risk of cervical or prostate cancer.

Untreated, trichomoniasis infection can last for months to years.


As with other sexually transmitted infections, the only way to prevent trichomoniasis is to not have sex. To lower your risk, use internal or external condoms correctly every time you have sex.

May 17, 2022

  1. Trichomoniasis: fact sheet. Centers for Disease Control and Prevention. https://www.cdc.gov/std/trichomonas/stdfact-trichomoniasis.htm. Accessed Feb. 9, 2022.
  2. Sexually transmitted infections treatment guideline, 2021: Trichomoniasis. Centers for Disease Control and Prevention. https://www.cdc.gov/std/treatment-guidelines/trichomoniasis.htm. Accessed Feb. 9, 2022.
  3. Trichomoniasis. Office on Women's Health. https://www.womenshealth.gov/a-z-topics/trichomoniasis. Accessed Feb. 9, 2022.
  4. Sobel JD, et al. Trichomoniasis. https://www.uptodate.com/contents/search. Accessed Feb. 9, 2022.
  5. Trichomoniasis. Merck Manual Professional Version. https://www.merckmanuals.com/professional/infectious-diseases/sexually-transmitted-diseases-stds/trichomoniasis. Accessed Feb. 9, 2022.
  6. Solosec (prescribing information). Symbiomix Therapeutics; 2021. https://www.solosec.com/. Accessed Feb. 10, 2022.
  7. Tosh PK (expert opinion). Mayo Clinic. X.


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