Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at February 5, 2016

Trichomoniasis, called trich for short, is one of the most common sexually transmitted diseases (STD) in the United States. About 7.4 million new cases of this infection occur each year.


Definition & Facts

Trichomoniasis is the most common curable sexually transmitted disease, affecting about 3.7 million people in the United States. Trich is caused by a protozoan infection from the parasite, Trichomonas vaginalis. The STD is much more common among women than men, and more frequently affects older women than younger women.

Symptoms & Complaints

Only about 30 percent of people who contract trichomoniasis ever develop symptoms. In fact, many don’t even realize they have an STD. When symptoms do develop, they vary between women and men.

Men who have trichomoniasis tend to experience itching around the penis and burning inside the penis, particularly during and after urination and ejaculation, as well as possible penile discharge. Those who are uncircumcised may experience inflammation of the foreskin.

For women, the disease may manifest with vaginal itching, redness, burning sensation, or soreness in the affected area, painful urination, pain during sex, and a thin, clear, white, green, or yellowish discharge with a strange smell. People of both genders may experience lower abdominal pain.

While most people who experience symptoms develop them between five to 28 days after infection, others don’t have symptoms until months after the initial infection. Left untreated, the parasite can persist in the body for years, increasing the risk for contracting or spreading other sexually transmitted infections, including HIV. Pregnant women who have the disease are at higher risk for delivering preterm babies and babies with low birth weight (under 5.5 pounds).


Trichomoniasis is spread when a person who is infected with the parasite passes it to another person during sexual activity. The one-celled protozoan parasite is tiny enough to be contracted through skin to skin contact.

For women, the vulva, vagina, and urethra are most often affected. Men usually develop the disease in the urethra. In general, this disease is most often passed between vagina and penis or vice versa, or during lesbian sex from one vagina to another through skin to skin contact. However, other parts that come in contact with the parasite, such as the hands, mouth, or anus, are rarely affected.

The parasite can also be spread by sharing sex toys that have not been washed between use or that have been used without a condom. A pregnant mother can pass the parasite to her baby before birth. However, you will not get trichomoniasis through kissing, hugging, sharing cups, plates or cutlery, toilet seats or towels.

Trichomoniasis, like other STDs, is more common among people who have more than one sexual partner or who switch back and forth between multiple partners. However, it’s possible to contract this infection even if you are in a monogamous relationship, especially because the parasite can exist in the body for months and years without causing symptoms.

Diagnosis & Tests

Because trichomoniasis rarely produces symptoms, it can only be diagnosed through testing by a healthcare provider. These tests are not always reliable, though they are significantly more reliable for women than for men. One test, known as a vaginal wet mount involves putting a sample of vaginal discharge on a slide and checking it under a microscope for presence of the parasite.

A culture test can be used to diagnose trichomoniasis in both men and women. Using urine or a swab from the urethra, this type of test grows a bacteria culture in the lab to make the parasite easier to find. Newer tests are more accurate, including DNA tests that can check for trichomoniasis, chlamydia, and gonorrhea using the same urine sample.

Women who think they may have trichomoniasis or another STD should schedule a medical exam during a time when they are not menstruating. They should avoid douches, vaginal sprays, and sexual intercourse during the 24 hours before the appointment.

It may take 10 days to get the results of a diagnostic test, during which time one should refrain from sexual activity. While it's possible to get a false negative test (meaning that a person has this infection, but it is not detected by lab tests), false positive tests are incredibly rare.

Treatment & Therapy

Once detected, trichomoniasis is curable with antibiotics, most frequently metronidazole or tinidazole. During trichomoniasis treatment, it's important to take all the medicine prescribed, even if symptoms resolve. Sex partners should also be treated for the disease, or the risk exists for contracting it again. One should abstain from sexual activity until all sexual partners have completed all prescribed medication. Most doctors recommend that people get tested again after three months to ensure that they're clear of infection.

Pregnant women who think they may have trichomoniasis should not take medication for the first three months, though it’s usually safe to take thereafter. If an individual is diagnosed with trichomoniasis and there’s a chance she could be pregnant, or if she is pregnant and has symptoms of an STD, it is important for her to let the doctor know right away so he or she can develop an appropriate, safe treatment plan. Those seeking treatment should also talk with their doctor about any other prescription or over-the-counter medications taken.

Prevention & Prophylaxis

The best way to prevent the spread of trichomoniasis and other STDs is to practice safe sex and use a latex condom correctly every single time that sexual contact occurs. However, it’s still possible to contract the parasite even with a condom, so before having sex with a new partner, both partners should get tested for STDs to avoid spreading them to one another.

Seeing a doctor immediately is necessary if unusual symptoms occur, such as a sore, rash, or pain in the genital area. Preventive treatment can help prevent the development of complications and from spreading an STD to sexual partners.