Trichomoniasis (Trich)

Medically Reviewed by Jabeen Begum, MD on May 07, 2024
Written by Kim Painter
6 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. It can also spread from one person's vagina to another person's vagina.

You can get the infection in your vulva, vagina, cervix, or urethra. It can also reach the 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.

If you have a vagina, you may notice:

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

If you have a penis, you might notice:

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

Asymptomatic trichomoniasis

Researchers aren't sure why only about 30% of people with the infection develop any symptoms. People assigned male at birth are especially unlikely to have symptoms.

The only way to know for sure if you have trich is to get tested.

Trichomoniasis tests

Physical exam. A doctor can look at your genitals and, if you have a vagina and cervix, do a pelvic exam. If you have trich, your cervix might be red and look like a strawberry.

Lab tests. The doctor might be able to quickly spot the parasites by looking at samples of your pee or genital fluids under a microscope. Sometimes, they might need to wait for a lab test called a culture. This is when the lab stores 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.

Home tests. Some health departments and online providers will let you pick up or order a test for trich that can be used at home if your state allows that. In that case, you usually collect a fluid sample from your genitals with a swab and send it to a lab. You'll get instructions on how to connect with a health care provider and get treated if you test positive.

Tests for other STDs. If you see a doctor, you might get additional tests, as many people with trich also have gonorrhea or chlamydia.

Trichomoniasis vs. bacterial vaginosis

Trich and bacterial vaginosis (BV) are both forms of vaginitis -- which just means an inflammation, infection, or change in the normal organisms in the vagina. A third form of vaginitis is a yeast infection. While they can have similar symptoms, each of these problems is caused by a different organism, so they're treated differently. BV is caused by an overgrowth of bacteria, while trichomoniasis is caused by parasites.

The treatment for trichomoniasis is an antibiotic. There are two main choices.

Trichomoniasis medications

These cure 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.

While you're taking metronidazole or tinidazole, you shouldn't drink alcohol. That's because the combination can cause nausea, vomiting, and a rapid heart rate. The medications also can cause side effects such as heart burn and a metallic taste in your mouth.

What to expect after treatment

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

Your sex partner or partners should also be treated, even if they don’t have symptoms. Don’t have sex for 7-10 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 and others assigned female at birth get tested for trich at least once a year if they have HIV.

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 avoid trich is to not have sex with other people. 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 before the genitals touch.
  • 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.

Trichomoniasis is a common STD that's caused by a parasite. It may or may not cause symptoms. If you find out you have trich, it's important to get treated to prevent spreading it or developing complications. Antibiotics work well against the infection.

How do you get trichomoniasis if you're not sexually active?

Trichomoniasis is almost always spread through sexual contact, but that doesn't always mean vaginal, oral, or anal sex. Partners can spread it through genital touching alone. You also could get trich by sharing sex toys if you don't wash them or cover them with condoms. Some researchers suggest that in rare cases, people might pick up trichomoniasis from towels, toilet seats, or swimming pools. However, you won't get trich from hugging or kissing.

It's also important to remember that trichomoniasis infections can linger unnoticed, so you might find out about an infection at a time when you're no longer having sex.

How long can you have trichomoniasis without knowing it?

You can have the infection for months or even years without knowing it because it often doesn't cause symptoms. You can only know for sure by getting tested, which you should do if a sex partner has tested positive or your doctor says you're at high risk. Then, you can get treated and cured.