Trichomoniasis, sometimes called “trich” (pronounced “trick”), is a common sexually transmitted infection (STI) that affects both females and males, but symptoms are more common in females.

Trichomoniasis is caused by the single-celled protozoan parasite, Trichomonas vaginalis. The vagina is the most common site of infection in girls and women, and the urethra (urine canal) is the most common site of infection in boys and men. The parasite is sexually transmitted throughsex (penis-to-vagina or vulva-to-vulva contact) with an infected partner. Women can get the disease from infected men or women, but men usually contract it only from infected women.

How common is trichomoniasis?

Trich is the most common, curable STI. Each year, there are about 1 million new cases of trichomoniasis in the United States. While trich affects both women and men, it is more common in women: the highest numbers of cases are in women between ages 16 and 35.

What are the signs and symptoms of trichomoniasis?

Only about 30 percent of people that have trich have any symptoms. Most males with trichomoniasis do not have any signs or symptoms. However, some males may have a temporary irritation inside the penis, mild discharge, or notice a slight burning after peeing (urinating) or ejaculating. Some females may have signs or symptoms which include:

  • discharge that is green, yellow or grey
  • a bad smell
  • itching in or around the vagina
  • pain during sex
  • pain when peeing (urinating)


How do I know if I have trich?

Trich can’t be diagnosed based on symptoms alone (keep in mind that many people don’t have any symptoms). A healthcare provider must perform a test to diagnose trich. Sometimes healthcare providers will put a sample of vaginal fluid or discharge on a slide so they can see the parasite under a microscope (this is called a “wet prep”). This test is not always reliable.

A culture test is another test for trich, and can be used with males and females. Culture tests use urine, or a swab from the vagina or urethra, and make the trich parasite easier to find by “growing” it in a lab.

Recently, tests that are much more accurate have become available, including DNA tests that are reliable in males and females. These tests can be done with vaginal swabs or urine. One of these tests even allows healthcare providers to check for trichomoniasis, chlamydia, and gonorrhea using the same sample.

What is the treatment for trich?

Trichomoniasis is curable with antibiotics. An antibiotic called Metronidazole (Flagyl) is usually prescribed. If you are prescribed treatment, use all the medicine prescribed, even if your symptoms go away. Your sex partners must also be treated, or you can get trich again. Don’t have sex until all partners have finished the medication.

Pregnancy and trichomoniasis

Trichomoniasis can cause babies to be born early or with low birth weight. If you think you may be pregnant be sure to tell your healthcare provider. Women in the first three months of pregnancy should not take medicine for trich because it might hurt the baby. You can take medicine after the first three months. Talk to your healthcare provider about them.

What about other complications?

Having trich can make it easier to become infected with the HIV virus or to pass the HIV virus on to a sex partner.

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