Fact checked by Nick Blackmer

• Online, some people are suggesting that swabbing your stool can lead to more accurate COVID test results.

• Experts say at-home tests sold in the U.S. are only intended to collect nasal specimens, and swabbing your stool can lead to false positive or negative results.

• For the most accurate results, people should use COVID at-home tests exactly as directed by the manufacturer’s instructions.

For years, swabbing your nose has been the tried-and-true method to test for COVID—but is it possible that users on X (formerly Twitter) have found a more effective method?

According to X user NurseKelsey, swabbing your poop instead of your nose might be the best way to get an accurate COVID diagnosis.

“Swabbed my cheek + nose: negative,” she wrote in her X post, published on January 31. “Swabbed my stool, per Twitter suggestion: positive.” That post has garnered more than 4,600 likes and has been seen by more than 450,000 people.

“I had three rapid tests & a doctor’s office (nasal) PCR all negative today,” she continued. “Don’t trust nasal swabs! Pro tip: test your stool!”

But while most X users seemed to be appreciative of NurseKelsey’s tip, experts aren’t convinced swabbing your excrement is the way to go for an accurate COVID diagnosis.

“The current at-home COVID-19 antigen self tests are not designed to detect SARS-CoV-2 proteins in stool, leaving any positive or negative result using a stool sample in doubt,” Mark Cameron, PhD, associate professor and infectious disease researcher at the Case Western Reserve University School of Medicine, told Health in a statement.

Here’s what experts had to say about swabbing stool to test for COVID, and how to ensure you’re testing for COVID safely and effectively.

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Is COVID Detectable in Stool?

Though COVID is typically thought of as a respiratory concern, the virus can show up in people’s feces.

Though less common than the telltale COVID symptoms like fever, cough, and fatigue, the SARS-CoV-2 virus can infect the gastrointestinal tract, leading to symptoms such as nausea, vomiting, and diarrhea.

People can shed the virus in their stool—it’s uncommon, but for some, this can happen weeks or even months after they were first infected with COVID.

Because of this, it’s possible to use stool sampling to identify or monitor COVID infections.

The Centers for Disease Control and Prevention (CDC) now use wastewater monitoring to estimate how many Americans are infected with COVID at any given time. This provides the organization with an earlier warning that more COVID is spreading in any given community.

While wastewater testing is a helpful way for public health officials to track COVID, that doesn’t guarantee that it’s going to work for an individual with an at-home COVID test, experts agreed.

“Wastewater tests are done using a tricky laboratory protocol which cleans up and dilutes the sample for PCR detection of virus sequences, not viral proteins like the home test,” Cameron said.

Most often, people shed viral RNA in their stool after or during a COVID infection, said John Sellick, DO, professor of medicine in the division of infectious diseases at the University at Buffalo. This means that the at-home antigen tests—which test for other COVID proteins—likely can’t pick up on that RNA, he told Health.

In that sense, it’s possible that somebody could get a false negative from trying to swab their stool via an at-home COVID test.

But false positives are equally plausible, experts agreed.

It’s possible that an at-home test could pick up some COVID proteins in the stool and come back positive, said Sellick. However, that doesn’t tell a person much about their current level of infectiousness.

“It may be someone who had COVID, they’ve already cleared the infection, but there may be some stray virus material lingering that you might pick up on a test,” he said.

Even if someone didn’t recently have COVID, using a stool sample could still lead to false positive results, said William Schaffner, MD, professor of infectious diseases at the Vanderbilt University Medical Center.

“There is a lot of ‘stuff’ in stool and it is not known whether any of that material could falsely create a positive result,” he told Health.

Related: Do COVID Tests Still Work for New Variants Like EG.5 and BA.2.86?

Making Sure Your At-Home Testing Is Accurate

Given that the virus that causes COVID can technically be detected in stool, it’s understandable why someone may want to give this method a try, especially if they’re not getting the results they were expecting from nasal swabbing.

However, for now, there isn’t enough evidence to prove that testing your stool for COVID can lead to any accurate results.

People should be especially skeptical if their stool swab results differ from their nasal or throat swab results, Sellick said.

“If [the stool swab] comes back positive and the nose is positive, okay, maybe that means something,” he said. “But if the nose is negative and the throat is negative…and the stool was positive, that doesn’t really mean much to me.”

If you’re experiencing COVID symptoms and are still testing negative with an at-home test, rather than testing your stool, wait and test again the next day, Schaffner recommended. In the case that you were exposed to COVID, wait three days and then test multiple times over the span of a couple of days for the highest chance of accurate results, he added.

People can also contact their healthcare provider about getting a PCR test, which tends to be more sensitive than at-home antigen tests.

In general, the key is to “always follow the simple directions explicitly,” Schaffner said. “Cutting corners reduces the reliability of the test.”

And with at-home nose swab tests being accurate and widely available, Sellick said, there isn’t much of a need to seek out stool sampling.

“I just don’t feel, at this stage of the game, that we really need it,” he said. “We’re usually able to make that diagnosis with the respiratory specimen.”

Related: What Are the Types of COVID Tests—And Which One Is the Best?

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