Trichomoniasis: A Common Sexually Transmitted Infection (STI)

A doctor’s guide to protecting yourself and others

“What the heck is trichomoniasis,” is the most common reaction to the diagnosis of this sexually transmitted infection. While not as common as HPV, chlamydia, and herpes, this less well-known infection affects 174 million people infected around the world each year. No one wants to hear it, but any sexually active person in a nonmonogamous relationship is potentially at risk.

What is trichomoniasis?

Trichomoniasis is a common and curable sexually transmitted disease caused by a single-celled protozoan parasite called Trichomonas vaginalis. The parasite lives in the urethra in men and the lower genital tract in women. The female anatomic parts included are the vagina, urethra (where urine comes out), and the cervix (the opening of the uterus).

The colloquial term for this STI is “trich” (pronounced Trick). Trichomonads are tiny parasitic bugs living in body fluids such as semen and vaginal secretions. They jump from one person to another when fluids transmit during sexual activity.

How do you know if you have trichomoniasis?

Most people have no symptoms at all. Only about 30% of people infected develop signs and symptoms meaning asymptomatic carriers pass the infection from one partner to another. An asymptomatic carrier is someone who has the disease but does not know it. Without testing, people who do not know they have trichomoniasis unknowingly spread the infection to their partners.

When symptoms occur, they appear one to four weeks after infection.

Typically, men do not have symptoms at all. Some men may have an irritation on the inside of the penis, mild discharge, testicular pain, or slight burning after urination or ejaculation.

Women have symptoms more often than men. Trichomoniasis causes a malodorous discharge that is frothy and yellow-green. It is a common cause of vaginal itching, often leading to incorrect self-treatment with over-the-counter yeast medication. This STI can lead to irritation of the genital area and discomfort during sex and urination.

Image courtesy of CDC. Trichomonas vaginalis flattens itself to attach to a vaginal cell. The unattached parasite can be seen on the right and is pear shaped

How do you catch trichomoniasis?

There are two ways most STDs are transmitted: fluid transmission or skin-to-skin contact. Trichomoniasis is a fluid transmitted infection. It is transmitted when bodily fluids from one person are shared with another via vaginal, anal, or oral sex. Fluids are present in the vagina, penis, mouth, and anus. Infections can occur even without ejaculation.

To keep things as clear as possible, any sexual act involving the exchange of bodily fluids allows trichomoniasis to spread from one person to another. The parasite can survive on surfaces for around 45 minutes. Sex toys should be properly cleaned after use.

How do you diagnosis trichomoniasis?

Most of the time, a simple physical exam can not accurately diagnose trichomoniasis. Experienced medical providers may suspect the infection based on the classic musty odor and appearance of discharge. A confirmation test is the most accurate way to diagnose this STI.

A microscope can be used to evaluate fluid from the vagina, penis, or urine to look for the parasites using a technique called a wet prep. A microscopic examination allows for immediate point-of-care diagnosis but will miss many infections. A nucleic acid amplification test (NAAT) is the most accurate way to confirm the infection.

The CDC does not have specific recommendations on who should get tested for trichomoniasis. Risk factors include new sex partners, multiple sex partners, men who have sex with men, a sex partner with concurrent partners, and a partner who has a sexually transmitted infection.

nucleic acid amplification test (NAAT) for STD’s

How is trichomoniasis treated?

Fortunately, we can easily treat trichomoniasis with antibiotics. It is a curable STI. Metronidazole is the most common antibiotic and is most effective when given in a single dose. High dose Metronidazole can cause nausea and one must avoid alcohol when taking this medication.

All sex partners should be notified, evaluated, tested, and treated. The parasite is harder to detect in men making male testing less reliable. Male partners of trichomoniasis positive women should be treated regardless of their results.

This strategy reduces the risk of reinfection by an untreated partner or the spread to future partners.

One should abstain from unprotected sexual contact until all partners have completed their treatment. I recommend a follow-up test to confirm treatment success (a test of cure), but this is not the official standard of care.

Prevention is key

Prevention is best achieved by abstinence from sexual activity or to be involved in a long-term, mutually monogamous relationship. The use of latex condoms consistently and correctly can reduce the risk of transmission.

Condoms are highly effective in preventing fluid transmitted sexually transmitted infections. Water-based lubricants combined with latex condoms provide the most protection. Non-water-based lubricants can break down latex and reduce protection.

Men and women with risk factors, including a new sex partner or multiple sex partners, should undergo testing.

Testing for all sexually transmitted infections helps keep you and your partners safe.


Medika Life has provided this material for your information. It is not intended to substitute for the medical expertise and advice of your health care provider(s). We encourage you to discuss any decisions about treatment or care with your health care provider. The mention of any product, service, or therapy is not an endorsement by Medika Life

Dr Jeff Livingston
Dr Jeff Livingston
Jeff is Co-Founder of Medika Life. He is a Board Certified Obgyn and CEO of MacArthur Medical Center in Irving, Texas. He is a nationally recognized thought leader, speaker, writer, blogger, and practicing physician who is considered an expert in the use of social media to educate patients, using new and innovative technology to improve care outcomes and the patient experience.


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