Sexual Health
Sexually Transmitted Infections and STDs

Trichomoniasis: What You Need to Know Today

Unlike the other six STIs, trichomoniasis is neither caused by a virus nor by a bacterium. The culprit is the protozoan T. vaginalis, which is a single-celled organism with long appendages called agella that the organism uses to propel itself. This STI, colloquially referred to as “trich”, is common in both heterosexual and homosexual women of all age groups as well as heterosexual men of all age groups.

Because the parasite is transferred via vaginal sex, gay and bisexual men rarely contract trich.

Trichomoniasis is often confused with trichinosis, which is caused by roundworms, and with trichuriasis, which is caused by whipworms. These two diseases are not STIs. They are spread by eating infected food. Trich is also sometimes confused with trichotillomania, a hair pulling disorder.


About one-third or more of infected people have no symptoms of trichomoniasis, although the infection can spread even when it’s asymptomatic. Not only that, but in 2012 researchers at Washington State University discovered a mechanism leading from trichomoniasis to prostate cancer. Also, pregnant women can pass the infection on to their offspring, and women with trich may be more likely to contract HIV/AIDS.

When symptoms of trichomoniasis do occur, they typically appear within five to 28 days after exposure as follows:
  • Pain, burning, and itching in the genitals that increases during urination and intercourse, for both men and women
  • For men: discharge from the penis
  • For women: an itchy, frothy, yellow-green vaginal discharge with a foul-smelling, “fishy” odor (Note: Bacterial vaginosis, a mild infection that is not an STI and is not dangerous, also has a discharge with a “fishy” smell. This is yet another reason to get an accurate diagnosis for your symptoms!)
  • Rarely, lower abdominal pain

Over-the-counter tests can check for whether vaginal discharge has an abnormally high pH count, meaning potassium hydroxide. However, conditions other than trich can cause a high pH count and counts are higher when blood, including menstrual blood, or semen are present. For these reasons, you should go to your doctor rather than rely on a home test – even if the test is normal but you continue to have symptoms.

The doctor will examine vaginal discharge for women and urine for men under a microscope to look for protozoa. This method only has a sensitivity of about 70%. The Centers for Disease Control and Prevention (CDC) recommends that healthcare providers use FDA-approved tests for trichomoniasis, including the highly sensitive nucleic acid amplification test (NAAT) and OSOM Trichomonas Rapid Test, a product of Seiksul Diagnostics.


Trichomoniasis, like the bacterial STIs, can be cured with antibiotics 90% to 100% of the time. Oral nitroimidazoles (metronidazole/flagyl and tinidazole/Tin- damax) are the only class of drugs used for treatment of trichomoniasis. Remember, your partner needs treatment as well or you can become reinfected.

Warning: Don’t drink alcohol during treatment and until twenty-four hours to seventy-two hours after completion of medication, depending on which drug is prescribed for you. Also, topical treatments for trichomoniasis are largely ineffective, so don’t rely on those.

Once again, as I’ve mentioned in the other articles in this STI series, please don’t be shy about discussing your sexual activity and concerns with your doctor, and please make sure your partners are tested for STIs – especially if the partners are new for you.

Here’s to your sexual health and pleasure from all of us at!

Sondra Forsyth is Co-Editor-in-Chief of

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