Trichomoniasis (Trich)

Medically Reviewed by Zilpah Sheikh, MD on September 25, 2023
4 min read

Trichomoniasis, also called trich, is a common sexually transmitted disease (STD).

Trich is caused by a tiny one-celled parasite named Trichomonas vaginalis. Anyone who’s sexually active can get it. It affects women more than men, older women more than younger ones, and African American women more than white or Hispanic women.

People with trich often don’t have any symptoms, and it doesn’t usually cause problems. But if you don’t get treatment, it raises your chances of getting or spreading other STDs, including HIV.

You get trich by having sex with someone who has it. Typically, it spreads through contact between a penis and a vagina. Women who have sex with women can also get trich through vaginal contact.

Women typically get the infection in their vulva, vagina, cervix, or urethra. Men usually get it in their urethra. They may also get it in their prostate, the gland between the bladder and the penis. It’s rare to have trich in other parts of your body, such as your hands, mouth, or anus.

Anyone who has trich can spread it, even if they don’t have symptoms.

About 70% of people with trich don’t have symptoms. In others, the signs might not show up until days or weeks after infection.

Women with trichomoniasis may have:

  • Vaginal fluid that smells bad and is greenish or yellowish
  • Genital itching, burning, redness, or soreness
  • Pain when they pee or have sex
  • The need to pee more often
  • Bleeding after sex

Men with trichomoniasis may have:

  • Itching or irritation inside their penis
  • A thin white discharge from the penis
  • Pain when they pee or have sex
  • The need to pee more often


Doctors can diagnose trich by taking a sample of pee or fluid from your genitals and looking at it under a microscope to spot the parasite. Sometimes, they might need to do a test called a culture. This is when they store the sample for several days so the parasite can grow and be easier to find under a microscope.

Sensitive tests called nucleic acid amplification tests (NAATs) can also spot signs of the parasite.

Your doctor might test you for other STDs at the same time because many people with trich also have gonorrhea or chlamydia.

Antibiotic medications like metronidazole (Flagyl, Noritate, Nuvessa) and tinidazole (Tindamax) clear up the infection in most people. Your doctor will give you pills to swallow, either in one large dose or in several smaller doses. Take all of the medicine, even if you start to feel better before you’re done.

Treatment will get rid of the parasite, but you can still get it again. About 20% of people get trich again within 3 months of treatment.

Your sex partner or partners should also be treated, even if they don’t have symptoms. Don’t have sex for 7 to 10 days after treatment. Your doctor might want to test you again before you have sex.

If you don’t get treatment, trich can lead to other health problems.

It can raise your risk of getting or spreading other STDs. If you have HIV, trich may make you more likely to spread it. Because of this risk, doctors suggest that women with HIV get tested for trich at least once a year.

If you’re pregnant, trich may make you give birth earlier than expected. Your baby may have a low birth weight, which can raise the chances of health or developmental problems. It’s rare, but your baby may also get trich as they go through the birth canal. You can get treated for trich while pregnant, so talk to your doctor about the best options for you.

The only way you can totally avoid trich is to not have vaginal sex. You can take other steps to lower your chances of getting it:

  • Always use latex condoms. Because you can get or spread trich through contact alone, make sure to put the condom on early, before it touches the vagina.
  • Avoid douching. Your vagina has a natural balance of bacteria to keep you healthy. When you douche, you remove some of those helpful bacteria, which can raise your chances of getting an STD.
  • Stick with one sex partner who’s tested negative for STDs. If that doesn’t work for you, think about limiting your number of sex partners.
  • Talk openly with your partners about your sexual histories and potential risk of infection. This can help you make the best choice for yourself.