Center for Young Women's Health

Trichomoniasis (Trichomonal Vaginitis)


  • Trichomoniasis is a sexually transmitted infection that affects both males and females.
  • Females may have symptoms such as discharge and irritation, or no symptoms. Males don't usually have symptoms.
  • You can infect another person even if you don’t have symptoms.
  • Trichomoniasis can be cured if both partners are treated with prescription medicine.
Getting Treatment:
The Division of Adolescent/Young Adult Medicine at Boston Children's Hospital offers special services in the diagnosis and treatment of trichomoniasis (trichomonal vaginitis).


Trichomoniasis is another common form of vaginitis. It occurs in both teens and adults.


Trichomonas (how it looks under a microscope)




What causes trichomoniasis?

Trichomoniasis is caused by a single-cell parasite called a trichomonad. Unlike yeast infections, you get trichomoniasis through sexual intercourse, so it is a sexually transmitted infection.


Who is a risk for trichomoniasis?

Approximately 3.7 million people in the United States are infected with Trichomoniasis. During sex, the parasite is transferred from male to female, female to male, male to male, and female to female. Trichomoniasis lives and multiplies in men, but hardly ever causes symptoms in men. Thus, a woman is often reinfected by her (male) partner who isn't aware of any symptoms. Women also may not know they have trichomoniasis for days or months and can spread the STI to their partner. Other women have symptoms of discharge or burning with urination. Only about 30% of people ever have symptoms indicating that they have the STI. The parasite affects the vagina, urethra (the canal that carries urine from the bladder to outside the body), and bladder of women and the penis of men. Since the parasite lives in both males and females, both sexual partners need treatment.


If a woman has more than one sexual partner, her chance of getting trichomoniasis is much higher. It's NOT spread by toilet seats.


What are some signs/symptoms of trichomoniasis?

The signs of trichomoniasis may include a yellow-gray-green, frothy vaginal discharge with a foul or fishy odor. The vagina may be sore and red and may burn and itch. It may be painful to urinate or have sexual intercourse. However, some women with trichomoniasis may not have any symptoms.


How can a health care provider tell if I have trichomoniasis?

A health care provider (HCP) will use a cotton swab to take a sample of your vaginal discharge and do some tests. With trichomoniasis, the pH level of your vagina will be higher (less acidic) than the normal level of 4.5, and the trichomonad parasite may be seen under the microscope. Trichomonads may be suspected by the results of a Pap test and you may be asked to come back to the office to see if you actually have the infection. Trichomoniasis can also be diagnosed by a culture or other special trichomonas DNA tests.


How is trichomoniasis treated?

If you're diagnosed with trichomoniasis, your HCP will give you a prescription for a specific antibiotic (most commonly metronidazole or tinidazole) for both you and your partner. (You and your partner should let your HCP know about any other medications that you're taking.) Both of you need to be treated since trichomoniasis is an STI.


Medication for trichomoniasis is only available by prescription. You and your partner need to take the whole dose of the medication for it to be the most effective. It's common to give the prescription in a single dose. Don't drink alcohol while you're taking the medication, or you'll vomit. If you take all of the antibiotic dose, trichomoniasis is usually cured. You and your partner should avoid sexual intercourse until both of you are completely cured. You can always be infected again if you don't take the proper precautions to prevent an STI.


How do you prevent trichomoniasis

The only way to prevent trichomoniasis completely is to not have sex. If you're going to have sex, a latex condom is the most effective way to lower your risk of getting trichomoniasis and other STIs.


Additional Information:


Trichomoniasis: CDC Fact Sheet


Written and reviewed by the CYWH Staff at Boston Children's Hospital


Updated: 12/11/2012


Related Guides:

Male Condoms

The male condom is a sheath (or covering) worn over the penis during intercourse. It prevents pregnancy by acting as a barrier, preventing semen from entering the vagina so the sperm can't reach her "egg"...

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