Trichomoniasis - A Common STD

Show Article Table of Contents

A young couple kissing in bed
fStop Images - Halfdark/Brand X Pictures/Getty Images

Trichomoniasis is a very common parasitic STD. It is caused by a single celled organism known as Trichomonas vaginalis. A curable STD, trichomoniasis, or "trich" is still extremely common. In fact, it is the most common curable STD in young women. The CDC estimates that more than 3 million people in the United States are infected with trichomoniasis.

It affects about 3 percent of the general population and 13 percent of African Americans. However, only around a third of people with trich will ever have any symptoms. 


Trichomoniasis affects both men and women. In women, it causes a vaginal infection called vaginitis. In men it infects the urethra, the tube inside the penis that carries sperm and urine. Men can only contract trichomoniasis from women. However, women can get the disease both from men and from other women with whom they have sexual contact.


Most men with trichomoniasis don’t have any symptoms. When they do, their symptoms are generally mild and include:

  • Discomfort in the penis
  • Pain on urination/ejaculation
  • Discharge

Symptoms in women are usually more severe than those seen in men. In women with symptoms, trichomoniasis symptoms generally occur within 1-4 weeks of initial infection. They include:

  • Frothy, colored discharge
  • Strong vaginal odor
  • Pain on intercourse/urination
  • Irritation and itching of the vagina and surrounding area.


In order to detect trichomoniasis, doctors take a swab of the vagina or urethra. Doctors then look at this swab under a microscope. This process is called a wet mount. It may also be used to detect yeast infections and bacterial vaginosis.

Since not all women with trichomoniasis will have visible organisms on a wet mount, doctors may also culture the vaginal secretions in a special medium. There is also a urine test for trichomoniasis, although it is not available in all doctors' offices. 

Trichomoniasis can also cause irritation of the cervix. This may be spotted by a doctor doing a gynecological exam, which could lead to testing. 


Trichomoniasis is generally treated with a single oral dose of metronidazole. Women may recognize this as one of the drugs that is also used to treat bacterial vaginosis.

It is important that your sexual partners be treated for trichomoniasis at the same time you are, and that you abstain from unprotected sex until your symptoms are gone, or else you will simply pass the disease back and forth.


Condoms have been shown to reduce the risk of infection from trichomoniasis. They should be used consistently if either partner is infected or might be at risk of infection. In addition, people should avoid having sex until they've been done with treatment for at least a week. That reduces the risk of re-infection. 

Women who have sex with women should consider using a barrier during vulva-to-vulva contact.

They should also know that the parasite can be transmitted by both fingers and sex toys. Appropriate use of condoms and gloves can make transmission between women less likely.

Side Effects

If you have trichomoniasis you are more susceptible to infection by HIV, the virus that causes AIDS. If you are an HIV positive woman, trichomoniasis makes it more likely that you will pass HIV to your sexual partners.

Trichomoniasis can also negatively affect the outcome of a pregnancy. Pregnant women infected with the parasite are more likely to have a pre-term birth. They are also more likely to give birth to a low birth weight baby.


Centers for Disease Control and Prevention (2016) STD Fact Sheet - Trichomoniasis.

Centers for Disease Control and Prevention (2015) Muzny CA, Blackburn RJ, Sinsky RJ, Austin EL, Schwebke JR. (2014) Added benefit of nucleic acid amplification testing for the diagnosis of Trichomonas vaginalis among men and women attending a sexually transmitted diseases clinic. Clin Infect Dis. 59(6):834-41. doi: 10.1093/cid/ciu446.