Trichomonas Infection: Symptoms, Diagnosis, & Treatment


What is trichomoniasis?


  1. Trichomoniasis (“trich”) is a sexually transmitted infection (STI) caused by the one-celled protozoan organism Trichomonas vaginalis.
  2. Trich is easily treated.
  3. Because its symptoms are similar to those of other STIs, a physical exam and laboratory tests are necessary for diagnosis.

Trichomoniasis (“trich”) is a sexually transmitted infection (STI). It is very common. According to the Centers for Disease Control and Prevention (CDC), 3.7 million Americans are infected with trichomoniasis at any given time. Trich is easily treated.

What are the symptoms of trichomoniasis?


Trich often has no symptoms. The CDC reports that only 30 percent of people with trich report any symptoms at all. In one study, 85 percent of affected women did not have any symptoms.

When symptoms do occur, they often begin five to 28 days after a person is infected. Although for some people it can take much longer.

The most common symptoms among women are:

  • vaginal discharge, which can be white, gray, yellow, or green, and usually frothy with an unpleasant smell
  • vaginal spotting or bleeding
  • genital burning or itching
  • genital redness or swelling
  • frequent urge to urinate
  • pain during urination or sexual intercourse

The most common symptoms in men are:

  • discharge from the urethra
  • burning during urination or after ejaculation
  • an urge to urinate frequently

What causes trichomoniasis?


Trich is caused by a one-celled protozoan organism called Trichomonas vaginalis. It travels from person to person through genital contact during sex.

In women, the organism causes an infection in the vagina, urethra, or both. In men, the infection only happens in the urethra. Once the infection begins, it can easily be spread through unprotected genital contact.

Trich is not spread through normal physical contact such as hugging, kissing, sharing dishes, or sitting on a toilet seat. In addition, it can’t be spread through sexual contact that doesn’t involve the genitals.

What are the risk factors for trichomoniasis?

Risk Factors

One million new cases of trich are estimated each year, according to the American Sexual Health Association and the CDC. Trichomoniasis is more common in women than in men, and 2.3 million women with the infection are between the ages of 14 and 49. It’s more common among older women than younger women. One study showed that women over 40 are twice as likely to be infected as previously suggested.

Your risk of infection can increase due to having:

  • multiple sexual partners
  • a history of other STIs
  • previous trichomoniasis infections
  • sex without a condom

How is trichomoniasis diagnosed?


Trich symptoms are similar to those of other STIs. It can’t be diagnosed by symptoms alone. See your doctor for a physical exam and laboratory tests if you think that you might have an infection.

A number of tests can diagnose trich, including:

  • cell cultures
  • antigen tests (antibodies bind if the Trichomonas parasite is present, which causes a color change that indicates infection)
  • tests that look for Trichomonas DNA
  • examining samples of vaginal fluid (for women) or urethral discharge (for men) under a microscope

How is trichomoniasis treated?

Complications Icon

Trichomoniasis can be cured with antibiotics. Your doctor may recommend metronidazole (Flagyl) or tinidazole (Tindamax). Do not drink any alcohol for the first 24 hours after taking metronidazole or the first 72 hours after taking tinidazole. It can cause severe nausea and vomiting.

Make sure your sexual partners are properly tested and take the medication, too. Not having any symptoms doesn’t mean they don’t have the infection. You will need to avoid sexual contact for a week after all partners have been treated.

What is the outlook for someone with trichomoniasis?


Without treatment, a trich infection can be ongoing. With treatment, trichomoniasis is usually cured within a week.

You can contract trich again after treatment if your partner was not treated or if a new partner has the infection. Reduce your chances of having the infection again by making sure all of your sexual partners get treatment. Then, wait for the infection to clear before becoming sexually active again. It is recommended that you wait one week after taking your medication before having sex again.

Your symptoms should go away after a week. If your symptoms continue longer, talk to your doctor about getting retested and retreated.

See your doctor for a follow-up test for trich at least three months after your treatment. The reinfection rate for women can be as high as 17 percent in the three months after treatment. Reinfection is possible even if your partners were treated as well. There are cases of trich being resistant to certain medications.

Some tests can be conducted as soon as two weeks after your treatment. Because of a lack of data supporting rescreening for men, they are generally not retested.

Are there any possible complications of trichomoniasis?


A trich infection can make it easier to contract other STIs. Genital inflammation caused by trichomoniasis can increase your risk of getting HIV, along with other STIs. It also becomes easier for you to spread the virus to someone else when you have trich.

Other conditions such as gonorrhea, chlamydia, and bacterial vaginosis often occur with trich. Untreated infections can result in pelvic inflammatory disease (PID). Complications of PID include:

  • fallopian tube blockage due to scar tissue
  • infertility
  • chronic abdominal or pelvic pain

Learn more: Pelvic inflammatory disease (PID) »

Trichomoniasis and pregnancy

pregnant women

Trich can cause unique complications in pregnant women. There can be a higher chance of delivering prematurely or delivering a baby with low birth weight. Although rare, the infection can be transmitted to the baby during delivery.

One study suggested that your child’s risk of developing an intellectual disability increases if you have trich during pregnancy.

It’s safe to take the medications metronidazole and tinidazole during pregnancy. No adverse effects have been noted.

If you are pregnant and suspect that you have trich or any other STI, talk to your doctor as soon as possible to prevent complications for you and your child.

How do you prevent trichomoniasis?


You can only fully prevent trich by abstaining from all sexual activity. 

Use latex condoms during sexual intercourse to reduce your chances of contracting trich and other STIs.

You Asked, We Answered

  • My partner has an STI, but I don’t have any symptoms. Why would I need to get tested or take the same medication?
  • STIs are common conditions among sexually active individuals. Often times people who have infections like chlamydia, gonorrhea, and trich do not have any symptoms. It is not uncommon for people to find out that they have an infection only after they have been tested. When a sexual partner is diagnosed with an STI, the CDC recommends that all partners be treated while waiting for test results on themselves. This lowers the chance of complications.

    For women, getting an STI is more complicated than it is for men. Because the vagina connects to the cervix, the opening to the uterus, this makes it easier for infections that start in the vagina to move up into the uterus, fallopian tubes, and abdominal cavity. This causes the serious condition PID.

    For men, delaying diagnosis and treatment means they risk developing more difficult to treat infections, as well as unknowingly passing the infection on to other people.

    The best way to prevent complications of STIs is to check for and treat infections before they become more serious.

    - Judith Marcin, MD

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