Trichomoniasis (trich): what is it, symptoms, treatment

Trichomoniasis is the most common non-viral sexually transmitted infection (STI) globally, accounting for an estimated 156 million cases (Rowley, 2019). And in the U.S. alone, more than 3.7 million people have trich. Yet, many haven’t heard of it and may not even know they have it (Partin, 2021).

About 80% of people who have trichomoniasis don’t have symptoms and don’t know they could be giving it to a partner. Though usually mild and treatable, trich can impact pregnancy, fertility, and increase the risk of getting other STIs and cervical cancer (Menezes, 2016; Yang, 2018).

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Unlike chlamydia or gonorrhea, which are caused by bacterial infections, trichomoniasis is a sexually transmitted infection caused by the parasite trichomonas vaginalis. 

This parasite is very small, and it lives in the human genitourinary tract (the vagina or penis), where it can survive—often unnoticed—for months or years. There, it damages and consumes cells, which can lead to red dots of raw skin inside the vagina (Kissinger, 2015).

The transmission of trich nearly always occurs through some type of sexual activity or the exchange of body fluids in the genital area. Vaginal sex is the most common route. Vulva-to-vulva sexual contact can also lead to a trich infection, along with passing vaginal fluids or semen via fingers or sex toys. Oral and anal sex, however, rarely transmit the infection (Carter-Wicker, 2016).

And while non-sexual transmission is very rare, trichomonas vaginalis can form cyst-like structures that allow for survival outside the human body in wet or moist areas for a short time. Researchers say this may explain rare cases of reported non-sexual transmission in bath water or on towels (Beri, 2020).

Only about 20% of people notice trich symptoms. These may present from 4 to 28 days after exposure or develop much later. Symptoms can also come and go (Menezes, 2016). 

Trichomoniasis symptoms in women include (Menezes, 2016):

• Increased vaginal discharge that can be clear, yellow, or greenish (sometimes frothy) that may have a fishy odor

• Itching, irritation, redness, pain

• Discomfort or burning during urination

• Discomfort or pain during sex 

Trichomoniasis symptoms in men include (Menezes, 2016):

• Itching or irritation inside the penis (urethra)

• Pain during urination

• Mild itching or burning after ejaculation

• Discharge from the penis (clear or containing mucus/pus)

It’s important to reach out to your healthcare provider if you notice any of these symptoms so that you can receive the right diagnosis and treatment.

As with other STIs, there are health risks associated with trich. Trichomoniasis may increase the risk of preterm labor, infertility, contracting other STIs, and cervical cancer. These risks are highest when trich remains untreated, emphasizing the importance of recognizing symptoms and receiving the appropriate treatment.

Preterm labor and low birth weight 

Pregnant women with trich are at risk for preterm delivery, having low birth weight infants, and rupture of the amniotic sac that surrounds the baby before week 37 of pregnancy. If the sac breaks, it can increase the risk of infection and having the baby early (Van Gerwen, 2021). 

Trich can also be spread to a baby during birth, impacting the baby's lungs or urinary tract. These infections often resolve on their own but may require treatment (Coleman, 2013). 

Infertility or subfertility

Untreated trichomoniasis is linked to inflammation and decreased fertility in men and women. In men, trich can cause urethritis, prostatitis, and epididymitis. These conditions can negatively affect male fertility. Research also shows trichomonas vaginalis can reduce sperm motility (Henkel, 2021; Schuppe, 2017). 

In women, untreated trich has been linked to pelvic inflammatory disease (PID), which can scar the fallopian tubes, preventing the fertilization of eggs (Wiringa, 2020). 

Sexually transmitted infections

Trichomonas vaginalis creates small sores inside the vagina, including around the cervix. Researchers believe by breaking down the vaginal wall, a trich infection makes it easier to contract sexually transmitted infections such as HIV (human immunodeficiency virus) and HPV (human papillomavirus) (Coleman, 2013; Belfort, 2021).

Cervical cancer

Research shows trich infections lead to an increased risk of cervical cancer. Studies show inflammation may play a role by making HPV infections—which are linked to cervical cancer—more severe (Belfort, 2021; Yang, 2018).

Even if you do notice signs of infection, symptoms alone are not enough to diagnose trich. A diagnosis typically includes one of the following tests (Schumann, 2021):

• Nucleic acid amplification test: Called NAAT for short, some STI and HIV clinics currently use these tests for routine screening programs. NAAT has been a gold standard for testing for gonorrhea and chlamydia. The test often shows greater than 90% sensitivity and specificity when testing for trichomonas vaginalis.

• Wet Mount (microscope): This traditional approach uses a microscope to find moving trichomonas vaginalis. It’s convenient and low cost. However, it’s only about 40%–60% effective since it only shows what’s in a small sample. 

During a consultation, a healthcare provider will usually ask about your sexual history and symptoms. They may suggest ruling out other conditions such as bacterial vaginosis if you’re a woman or prostatitis if you’re a man (Schumann, 2021).There are three separate treatment strategies for trich that involve oral medications. Healthcare providers typically use one of the following approaches (Schumann, 2021):

• A single dose (2-gram) of metronidazole 

• A single dose (2-gram) of tinidazole 

• For patients with HIV infection, a 7-day course of 500 mg metronidazole twice daily may be recommended. 

It’s important for pregnant women to receive treatment to prevent preterm labor. 

You should not consume alcohol while using these medications. Healthcare providers typically advise avoiding alcohol until 24 hours after the final dose of metronidazole and 72 hours after the tinidazole dose. 

To avoid reinfection, sexual partners should receive treatment simultaneously and avoid sex until the treatment is complete. Expedited partner therapy laws (in many states) may allow a provider to prescribe treatment to a sexual partner without an exam or patient relationship.

Additionally, your healthcare provider may ask you to schedule a follow-up appointment after about two weeks to ensure your body has cleared the infection. The CDC recommends follow-up testing within three months from the initial test. Follow-ups are important because some people have drug-resistant strains of trich, which may require a different medication. 

Healthcare providers outline the following ways to reduce your chances of getting trichomoniasis if you’re sexually active: 

• Talk with your partner about risks for STIs.

• Use condoms correctly. Research shows the consistent and correct use of condoms does provide a good amount of protection against STIs like trich (Crosby, 2012). 

• Assume any fluids from the vagina or penis may harbor trichomonas vaginalis; experts suggest not sharing intimate items like sex toys and point out that you don’t have to have intercourse to be infected.

Any time you have symptoms of an STI or concerns about your sexual health, it’s important to seek medical advice. A healthcare provider may ask about your sex partners and whether you are pregnant or plan to become pregnant.  

Ask your healthcare provider about what types of STIs you should be aware of and whether you should have a trichomoniasis screening. If you receive a diagnosis of trichomoniasis, know that it’s common and treatable. 

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Current version

February 22, 2022

Written by

Kristin DeJohn

Fact checked by

Steve Silvestro, MD

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About the medical reviewer

Steve Silvestro, MD, Ro

Dr. Steve Silvestro is a board-certified pediatrician and Associate Director, Clinical Content & Education at Ro.