Trichomoniasis is a sexually transmitted infection caused by a parasite. In women, trichomoniasis can cause a foul-smelling vaginal discharge, genital itching and painful urination. Men who have trichomoniasis typically have no symptoms. Pregnant women who have trichomoniasis may be at higher risk of delivering their babies prematurely.
To prevent reinfection with the organism that causes trichomoniasis, both partners should be treated. The most common treatment for trichomoniasis involves taking one megadose of metronidazole (Flagyl, Tindamax). You can reduce your risk of infection by using condoms correctly every time you have sex.
Many women and most men with trichomoniasis have no symptoms, at least not at first. Trichomoniasis signs and symptoms for women include:
- A profuse and often foul-smelling vaginal discharge — which may be white, gray, yellow or green
- Genital redness, burning and itching
- Pain with urination or sexual intercourse
Trichomoniasis rarely causes symptoms in men. When men do have signs and symptoms, however, they may include:
- Irritation inside the penis
- Burning with urination or after ejaculation
- Discharge from the penis
When to see a doctor
See your doctor if you have a foul-smelling vaginal discharge or if you experience pain with urination or sexual intercourse.
Trichomoniasis is caused by a one-celled protozoan, a type of tiny parasite that travels between people during sexual intercourse. The incubation period between exposure and infection is unknown, but it's thought to range from five to 28 days.
Risk factors include having:
- Multiple sexual partners
- A history of other sexually transmitted infections
- A previous episode of trichomoniasis
- Having sex without a condom
Pregnant women who have trichomoniasis may:
- Deliver prematurely
- Have a baby with a low birth weight
- Transmit the infection to the baby as he or she passes through the birth canal
Having trichomoniasis also appears to make it easier for women to become infected with HIV, the virus that causes AIDS.
Your family doctor, gynecologist or a medical practitioner at an urgent care center can diagnose and prescribe treatment for trichomoniasis.
What you can do
Before the appointment, you might want to prepare a list that includes:
- A detailed description of your symptoms, including when they started
- Sexually transmitted infections you've had
- The number of sexual partners you've had during the past few years
What to expect from your doctor
For women, your doctor will perform a pelvic exam and may take a sample of your vaginal fluids for testing.
The diagnosis of trichomoniasis can be confirmed by looking at a sample of vaginal fluid for women or urine for men under a microscope. Growing a culture used to be the way to diagnose trichomoniasis, but newer, faster tests, such as rapid antigen tests and nucleic acid amplification, are more common now.
The most common treatment for trichomoniasis, even for pregnant women, is to swallow one megadose of either metronidazole (Flagyl) or tinidazole (Tindamax). Both you and your partner need treatment. And you need to avoid sexual intercourse until the infection is cured, which takes about a week.
Don't drink alcohol for 24 hours after taking metronidazole or 72 hours after taking tinidazole, because it can cause severe nausea and vomiting.
As with other sexually transmitted infections, the only way to prevent trichomoniasis is to abstain from sex. To lower your risk, use condoms correctly every time you have sex.
March 21, 2015
- Sobel JD. Trichomoniasis. http://www.uptodate.com/home. Accessed Jan. 23, 2015.
- Trichomoniasis fact sheet. Centers for Disease Control and Prevention. http://www.cdc.gov/STD/Trichomonas/STDFact-Trichomoniasis.htm. Accessed Jan. 23, 2015.
- Hobbs MM, et al. Modern diagnosis of trichomonas vaginalis infection. Sexually Transmitted Infections. 2013;89:434.