Everything You Need to Know About Trichomoniasis (Trich)

Medically Reviewed By Joseph Vinetz, MD
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Trichomoniasis is a sexually transmitted infection (STI). Symptoms of the infection vary from person to person. Many people have no symptoms, while others get symptoms shortly after infection. A laboratory test can diagnose trichomoniasis. With early diagnosis, the infection is easily treatable. Trichomoniasis can lead to serious complications without treatment, such as preterm delivery for pregnant people or an HIV infection. Doctors treat trichomoniasis with antibiotics.

This article provides an overview of trichomoniasis, including its symptoms, causes, diagnosis, and treatment options.

Sex and gender terms

Sex and gender exist on spectrums. This article will use the terms “men” and “women” to refer to a person’s sex assigned at birth.

What is trichomoniasis?

A couple talks to a doctor
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Trichomoniasis is an STI caused by a parasite. It spreads through anal, oral, and vaginal sex. In women, the parasite infects the lower genitourinary tract. The infection involves the prostate or urethra in men. 

Most people do not know that they have trichomoniasis because they do not show any symptoms. Having an asymptomatic infection means that people can unknowingly spread the parasite to others.

How common is trichomoniasis?

Trichomoniasis infection is one of the most common STIs in the United States. According to the Centers for Disease Control and Prevention (CDC), there were about 2.6 million cases in 2018. 

In the U.S., the highest number of cases occur in women ages 14–59 years. The prevalence is about 2.1% in that group, and the prevalence is around 0.5% in men.

The CDC reports that trichomoniasis prevalence is higher in certain groups. These groups include:

  • African American women
  • people with lower educational levels or higher poverty levels
  • unmarried people
  • women who first have sex at a young age

What causes trichomoniasis?

The parasite Trichomonas vaginalis causes trichomoniasis. It spreads through sexual contact, including anal, oral, and vaginal sex. Women can get it from either men or women who have the infection. Men usually get it from women.

The parasite is not likely to survive in other body parts, such as the mouth.

What are the symptoms of trichomoniasis?

Trichomoniasis symptoms mainly affect the genitals and urinary tract in men and women. However, about 70% of people with the infection have no symptoms.

When symptoms do occur, they usually show up within 5–28 days of infection. It is possible to develop symptoms after that time or have them come and go.

Common trichomoniasis symptoms in women

In women, trichomoniasis symptoms may include:

Common trichomoniasis symptoms in men

In men, common symptoms may include:

  • burning with ejaculation
  • itching or irritation of the urethra, which is the tube that carries urine from the bladder through the penis
  • pain or burning with urination
  • urethral discharge

How do doctors diagnose trichomoniasis?

To diagnose trichomoniasis, your doctor will review your medical history and perform an exam.

For women, this will include a pelvic exam. Your doctor will swab the inside of your vagina to get a fluid sample. Examining the sample under a microscope can help your doctor identify the parasite. Alternatively, your doctor may order laboratory tests.

For men, doctors will take the swab sample from the urethra. 

If the tests are positive for trichomoniasis, your doctor will likely order other STI tests.

How do doctors treat trichomoniasis?

Trichomoniasis is easy to treat. Treatment options include:

  • metronidazole (Flagyl) as a single 2-gram (g) oral dose
  • tinidazole (Tindamax) as a single 2-g oral dose

For people with an HIV infection, doctors may prescribe smaller doses of metronidazole over a week. Metronidazole is safe for pregnant people. However, those who have recently given birth should avoid breastfeeding during treatment.

It is also important for anyone with the infection to avoid drinking alcohol while receiving treatment, as these drugs can cause serious side effects, such as severe nausea and vomiting.

It is possible to get trichomoniasis again after treatment. In fact, about 20% of people will have another infection within 3 months of treatment. To reduce the risk of reinfection, all sexual partners should get treatment simultaneously and abstain from sex for about a week after treatment.

What are the potential complications of trichomoniasis?

Trichomoniasis treatment is usually successful. Complications can develop if the infection is left untreated, especially in pregnancy.

Having trichomoniasis also increases the risk of contracting HIV and other STIs if you come into contact with a person who has an infection. If you have HIV, having trichomoniasis as well makes it easier to pass HIV to others.

An untreated infection can also lead to epididymitis, prostatitis, and infertility in men.

How does trichomoniasis affect pregnancies?

Trichomoniasis poses two major risks to pregnancies:

  • low birth weight, which occurs when a baby weighs less than 5.5 pounds
  • premature birth, which is delivery before 37 weeks of pregnancy

These situations increase the risk of health and developmental problems for the baby. Metronidazole can treat trichomoniasis at all stages of pregnancy.

What is the outlook for trichomoniasis?

Treatment with metronidazole has a cure rate of 90–95%. When sexual partners also take treatment, the cure rate is higher. It usually takes about a week for the symptoms to clear.

It is common for sexually active individuals to experience reinfection.

What are the risk factors for trichomoniasis?

Several factors increase the risk of getting trichomoniasis. Not all people with risk factors will get the infection. Risk factors include:

  • a history of STIs
  • IV drug use, which means injecting drugs into a vein
  • multiple or new sexual partners
  • sexual contact with a person who has the infection
  • unprotected sexual intercourse

How can you prevent trichomoniasis?

The only sure way to avoid trichomoniasis and other STIs is to abstain from all forms of sex.

If you are sexually active, you can reduce your risk by:

  • having sex only within a mutually monogamous relationship with a partner who does not have the infection
  • talking with new partners about STIs before you agree to have sex
  • using a latex condom or another barrier method every time you have sex

FAQ

The following are some common questions and answers about trichomoniasis.

Can you get trichomoniasis without being sexually active?

Trichomoniasis is an STI. You can get it through direct sexual contact.

You can avoid trichomoniasis by abstaining from sexual contact.

What will happen if trichomoniasis is left untreated?

Without treatment, trichomoniasis can cause complications during pregnancy.

It also increases the risk of contracting HIV and other STIs and the risk that someone with HIV will pass the infection to others.

Epididymitis, prostatitis, and infertility can occur in men who do not seek treatment.

Summary

Trichomoniasis is a very common but highly treatable STI.

However, most people do not know that they have the infection because they do not have symptoms. When symptoms occur, they include genital itching and discharge.

Treatment with one large dose of antibiotics usually cures the infection.

Talk with your doctor if you are experiencing any symptoms consistent with trichomoniasis.

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Medical Reviewer: Joseph Vinetz, MD
Last Review Date: 2022 Apr 14
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