Even if you're pretty clued-up about sexual health, there's a chance you may not have heard of trichomoniasis. What is trichomoniasis, you might be wondering. 

Trichomoniasis, or "trich" for short, is a type of STI caused by a parasite. It's very common, and most people with trich don't experience any symptoms.

While trichomoniasis might not be as well-known as other sexually transmitted infections like HIV, gonorrhea, or chlamydia, it's actually estimated to be the most common non-viral STI in the U.S. The Centers for Disease Control and Prevention (CDC) reports that almost 2 million people in the U.S. test positive for trichomoniasis each year, most of whom are women. 

And yet, trichomoniasis isn’t a reportable disease, which means that health departments are required to report it, so it can be challenging for public health programs to keep track of it and manage it effectively.

However, like with all STIs, awareness is key — especially if you're sexually active. Below, we give you the lowdown on the symptoms, causes, and treatments for trichomoniasis.

What are the symptoms of trichomoniasis?

Trichomoniasis can be tricky because it often doesn't show symptoms, meaning people may not even realize they have the infection. Around 70% of those with trichomoniasis don't experience any signs or symptoms at all, according to the CDC. 

However, when symptoms do show up, the most common one is vaginitis (irritation in the vulva or vagina) and abnormal vaginal discharge. Trichomoniasis has an incubation period of around 5 to 28 days, according to the CDC — but it might take way longer for symptoms to show up.

Some common signs and symptoms of trichomoniasis include: 

Keep in mind that other sexually transmitted infections or vaginal infections can cause similar symptoms, so if you're experiencing symptoms that you think might be trichomoniasis, it's important to get tested to get a proper diagnosis and exclude any other infection. 

What does trichomoniasis smell like

Unusual and foul-smelling discharge is a dead giveaway that something’s up down there, and it’s one of the most common signs of trich. Trichomoniasis discharge usually has a strong, unpleasant, and sometimes fishy smell. It’s worth noting, however, that other infections can cause foul-smelling discharge so that alone isn’t enough to diagnose trich. 

Trichomoniasis vs BV

Although trichomoniasis and bacterial vaginosis (BV) can cause similar symptoms — like unusual, foul-smelling discharge — and are treated with an antibiotic called metronidazole, they're distinct infections. 

BV happens when there's an overgrowth of "bad" bacteria (typically Gardnerella vaginalis) in your vaginal microbiome, while a parasite causes trichomoniasis. More importantly, trichomoniasis is a sexually transmitted infection, while BV isn't. 

What is trichomoniasis caused by?

Unlike other common STIs, trichomoniasis isn't caused by bacteria or a virus. It's caused by a parasite called Trichomonas vaginalis (TV), a single-celled organism known as a protozoan parasite.

Trichomoniasis can spread through sexual contact and bodily fluids such as semen and vaginal fluid. So, if you want to prevent trichomoniasis, remember to use a condom or dental dam.

It tends to thrive in moist environments like the urethra, vagina, and vulva, which means women have an increased risk of contracting trich. The pH of the vaginal microbiome also helps TV to grow.

Can men get trichomoniasis?

Anyone who is sexually active can get trich, but men and people with a penis are less likely to get trichomoniasis — or show symptoms. When they do get trichomoniasis, the infection is usually just in the urethra

Symptoms of trich in men include:  

  • discharge from the penis
  • pain or burning when peeing
  • the frequent need to pee.

How to test for trichomoniasis

If you have a vagina, it's pretty easy to get tested for trichomoniasis with a simple vaginal swab. Even if you don't have any symptoms, it's always a good idea to regularly include trichomoniasis testing in your STI screening routine. 

However, remember that trichomoniasis tests are not typically part of every STI panel, so you may have to request it specifically. Alternatively, you can also do an at-home test for trichomoniasis, such as Evvy's Expanded PCR Panel and Vaginal Health Test, by taking the sample yourself and sending it to a lab for analysis.

How is trichomoniasis treated?

If your trichomoniasis test comes back positive, your healthcare provider or OB-GYN will prescribe a simple oral antibiotic to treat the infection in about a week. 

Two common medications can be used: metronidazole, which is usually provided in a single dose, and tinidazole, which is generally taken in a lower dose twice a day for seven days. Make sure not to drink alcohol during this time!

It's worth noting that your sex partner will also have to get treated for trichomoniasis, even if they don't have any symptoms. People with a penis rarely have any symptoms of trichomoniasis, but that doesn't mean they don't have the infection. And if they don't get treated, they might spread trich back to you or other sex partners.

Reasons why trichomoniasis won't go away

Trichomoniasis is easily treatable, but like many infections, it has a nasty habit of being stubborn. There are a few reasons why trichomoniasis won’t go away: 

  • You didn’t take the whole course of antibiotics. Remember always to finish your medication even if you start feeling better or symptoms go away.
  • You were misdiagnosed or prescribed an inadequate dose of antibiotics.
  • You had sexual contact with your partner(s) before the infection was fully treated.
  • You developed antibiotic resistance while taking antibiotics.
  • Your partner wasn’t treated for trichomoniasis.
  • Treatment was successful, but the trichomoniasis came back. Reinfection happens in about 1 in 5 people within three months of treatment.

What happens if trichomoniasis is left untreated

It's really important to treat any STIs you may have because they can cause serious health problems when they go unchecked. Trichomoniasis, in particular, can cause inflammation in your genital area and increase the risk of getting other STDs, like human immunodeficiency virus (HIV). 

Trichomoniasis can be especially dangerous to pregnant women. Although it's rare, if you're pregnant and have trichomoniasis, it could lead to preterm delivery or a low birth weight. So, if you're pregnant and experiencing symptoms of trichomoniasis, it's really important to talk to your doctor right away. 

Untreated trichomoniasis can also cause cervicitis, which is inflammation of the cervix for people with vaginas. Symptoms of cervicitis may include bleeding between periods, pain during or after sex, and abnormal discharge.

The good news is that, unlike STIs like chlamydia and gonorrhea, trichomoniasis can't travel up from the lower genital tract into your uterus and ovaries, which means it can’t cause pelvic inflammatory disease (PID).

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What is the main cause of trichomoniasis?

Trichomoniasis is caused by a tiny parasite called Trichomonas vaginalis. The parasite spreads through semen or vaginal fluids during sexual contact, including vaginal sex, oral sex, or anal sex.

What are 3 trichomoniasis symptoms?

Trichomoniasis can often go unnoticed, so many people may not even realize they have it. When it does cause symptoms, the most common ones are foul-smelling vaginal discharge, vulvar pain or itchiness, or pain while peeing or having sex.

Is trichomoniasis an STD?

STD stands for “sexually transmitted diseases,” and STI stands for “sexually transmitted infection.” Both STDs and STIs are infections that can be passed from one person to another through sexual contact, such as trichomoniasis. 

How long does it take for trichomoniasis to show up?

It can take trichomoniasis anywhere from 5 to 28 days, according to the CDC, but some people don’t develop symptoms until much later.

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