Trichomoniasis is a common, curable sexually transmitted infection (STI) caused by a tiny parasite. The catch: about 70% of people have no symptoms at all. When trichomoniasis symptoms do appear, they include unusual genital discharge, itching, and pain when urinating. A simple lab test confirms it, and a course of antibiotics cures it.
What is trichomoniasis?
Trichomoniasis, often shortened to "trich," is an STI caused by a single-celled parasite called Trichomonas vaginalis. It spreads through sexual contact and most often infects the lower genital tract: the vagina and urethra in women, and the urethra in men.
It is one of the most common curable STIs worldwide, with the World Health Organization estimating around 156 million new infections each year. Because most infections cause no noticeable signs, many people pass it on without knowing they have it.
Trichomoniasis symptoms
Most people with trichomoniasis have minimal or no symptoms. When symptoms do appear, they usually begin 5 to 28 days after infection, though they can also start much later or come and go.
Symptoms in women
Women are more likely than men to notice symptoms, which may include:
- A change in vaginal discharge that is thin, frothy, or unusual in amount, often yellow-green and sometimes with a fishy smell
- Itching, burning, redness, or soreness around the genitals
- Discomfort or pain when urinating
- Pain or discomfort during sex
- Lower abdominal discomfort (less common)
Symptoms in men
Symptoms in men are usually mild or absent, but can include:
- Discharge from the penis
- Itching or irritation inside the penis
- Burning after urinating or ejaculating
- A more frequent need to urinate
How trichomoniasis is diagnosed
It is not possible to diagnose trichomoniasis from symptoms alone, because its signs look like other infections such as chlamydia and gonorrhea. A healthcare provider confirms it with a laboratory test.
Testing usually involves one of the following:
- A swab of fluid from the vagina or, for men, the urethra
- A urine sample
- Lab analysis using rapid antigen tests or highly accurate molecular (NAAT) tests
Trichomoniasis is not always included in a standard STI screen, so it is worth asking your provider whether you are being tested for it. To understand how broader screening works, see our STI testing guide and the pillar overview of STIs and testing.
Trichomoniasis treatment
Trichomoniasis is the most common curable STI, and treatment is straightforward: oral antibiotics from the nitroimidazole class, most often metronidazole.
Based on CDC and NHS guidance, typical regimens include:
- Metronidazole 500 mg twice a day for 7 days, the preferred course for women
- Metronidazole as a single 2 g dose, often used for men
- Tinidazole as a single 2 g dose, an alternative option
A few important points about treatment:
- Treat partners together. All sexual partners need treatment at the same time, even without symptoms, to stop reinfection.
- Finish the full course. Take every dose as prescribed, even if symptoms improve quickly.
- Wait before having sex. Avoid sex until at least one week after you and your partners have completed treatment and symptoms have resolved.
- Reinfection is common. A notable share of people are reinfected within 3 months, so providers often recommend retesting around the 3-month mark.
Why treating trichomoniasis matters
Although symptoms are often mild, untreated trichomoniasis is not harmless. It can cause genital inflammation that makes it easier to acquire or transmit other infections, including HIV. In pregnancy, trichomoniasis has been linked to early or low-birth-weight delivery, so it is important to mention symptoms to your provider if you are or may be pregnant.
Preventing trichomoniasis
You can lower your risk with the same steps that reduce other STIs:
- Use condoms consistently and correctly
- Get tested regularly, especially with new partners
- Ensure partners are tested and treated when one person is diagnosed
For a fuller plan, see our guide on how to prevent STIs.
The bottom line
Trichomoniasis is extremely common, easy to miss, and easy to cure. Because most people have no symptoms, you cannot rely on how you feel to know whether you have it; testing is the only way to be sure. If you notice unusual discharge, itching, or painful urination, or if a partner is diagnosed, see a healthcare provider. A short course of antibiotics, taken alongside your partners, clears the infection and helps prevent it from coming back. This article is general education and not a substitute for individualized medical advice.
