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What Is Trichomoniasis?

Trichomoniasis is a sexually transmitted infection (STI) caused by the protozoan parasite Trichomonas vaginalis. This common STI is also referred to as “trich.”

Trichomoniasis is curable. However, you can become infected again if you have sex with an infected person. Most men and women don’t get treated for it right away because they don’t realize they’re infected with the parasite. In the meantime, they can spread the infection to others.

According to the Centers for Disease Control and Prevention (CDC), trichomoniasis affects nearly 3.7 million people in the United States. Only around 30 percent of those individuals are symptomatic. If you have no symptoms, you can still spread the infection.

Trichomoniasis is spread through sexual contact. It can be transmitted through contact between the penis and the vagina or contact between the vagina and the vagina. The parasite doesn’t generally infect the mouth or anus.

What Are the Symptoms of Trichomoniasis?

Most people with trichomoniasis don’t have any symptoms. The CDC estimates that only about 30 percent of people experience symptoms.

When women have symptoms, they may include:

  • itching or redness of the vaginal area
  • uncomfortable urination
  • the urge to urinate frequently
  • frothy, vaginal discharge that may be yellow or green in color
  • foul vaginal odor
  • swelling in the groin

Men rarely have symptoms, but when they do, symptoms may include:

  • itching inside the penis
  • burning after urination or ejaculation
  • the urge to urinate frequently
  • penile discharge

Symptoms might appear five to 28 days after being infected. In some cases, they can develop much later, according to the CDC. It’s not unusual for symptoms to be sporadic.

Am I at Risk for Trichomoniasis?

Engaging in sexual activity puts you at risk for catching trichomoniasis from your partner. Other risk factors include:

  • having multiple sexual partners
  • a history of other STIs
  • prior infection with trichomoniasis
  • sex without a condom

Diagnosing Trichomoniasis

Diagnosing trichomoniasis is easier in women than in men.

Diagnosing Women

Your doctor or gynecologist will ask you about your symptoms and about any recent sexual activity. The infection can be diagnosed during a pelvic exam. It may cause red patches on the vaginal wall or cervix.

A swab may also be used to collect a sample of vaginal fluids. This can be examined under a microscope to look for the parasite.

Diagnosing Men

It’s very difficult to diagnose this STI in men. Therefore, men are usually treated if their sexual partner is diagnosed with this infection. If there’s discharge or if you have persistent itching or burning in the urethra, your healthcare provider will swab the urethra to get a sample of any discharge. The discharge can be examined under a microscope to look for the parasite.

How Is Trichomoniasis Treated?

You will need to take a prescription medication, usually metronidazole, to get rid of the infection. These pills are taken orally. Trichomoniasis may also be treated with tinidazole.

You should not drink alcohol while taking metronidazole or tinidazole or for up to 72 hours afterward. Alcohol mixed with these medications can cause nausea and vomiting.

Sexual activity of any type should also be avoided until you’re done with treatment. Treatment doesn’t protect you from future infections. It’s possible to become infected again. It’s important for both sexual partners to be treated before resuming intercourse.

Men may be treated for this infection if they have symptoms that persist and the treatment for other STIs has been ineffective.

Long-Term Complications

If you’re pregnant and have trichomoniasis, your baby may be born prematurely. Babies born to women who are infected tend to have a low birth weight. It’s safe for you to treat this infection while you’re pregnant. If you have any concerns, talk with your doctor about your treatment.

Without treatment, trichomoniasis can cause changes in your cervical tissue. These changes may show up on a Pap smear. If your doctor finds abnormal cells, you’ll be treated and then have a repeat Pap smear.

Trichomoniasis can also make it easier for women to get infected with HIV, the virus that causes AIDS. According to the World Health Organization (WHO), some STIs increase the risk of getting HIV three-fold or more.

How to Lower Your Risk of Infection

Abstaining from sexual intercourse is the only sure way to prevent trichomoniasis or to avoid spreading it to others. Latex condoms used correctly can reduce the risk of spreading this infection. However, condoms are not foolproof. The parasite can still be transmitted from surrounding areas.

It’s important to talk to your partner about your sexual history and to get tested before starting a sexual relationship.

If you already have trichomoniasis, don’t have sex until you and your partner both complete treatment. It’s also important to:

  • inform your sex partners about the infection
  • make sure you and your sex partners are treated and then tested again before continuing sexual activity
  • unless you’re in a stable, monogamous relationship and both partners have been tested, use latex condoms every time you have intercourse        

Call your healthcare provider if you begin to experience any symptoms. If you’re having unprotected sex or sex with multiple partners, be sure to get tested regularly for STIs, even if you don’t have any symptoms.

Content licensed from:

Written by: Lauren Reed-Guy and Tim Jewell
Published on: Oct 21, 2015
Medically reviewed on: Aug 31, 2016: Judith Marcin, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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