The Centers for Disease Control and Prevention has an important request for people this summer: Please don't go in the pool if you have diarrhea.
CDC-Diarrhea-Warning-in-Swimming-Pools-GettyImages-673125673 , a child goes down a pool slide, leaving a brown trail in her wake. "Don't swim or let your kids swim if sick with diarrhea. One person with diarrhea can contaminate the entire pool," the CDC wrote alongside it.
Another GIF shows a different child swimming in a pool, shooting out diarrhea. "Diarrhea and swimming don't mix!" the CDC wrote, after comparing swimming near someone with diarrhea to snorkeling in a toilet.
The CDC also linked to its "steps for healthy swimming" website page, which echoes the warning against hitting the pool when you have diarrhea. The CDC specifically mentions the microscopic parasite Cryptosporidium, which is protected by an outer shell that allows it to survive for long periods of time and is resistant to chlorine. Cryptosporidium is a leading cause of waterborne disease in people in the US, the CDC says. The most common symptom is watery diarrhea that lasts from one to two weeks.
While plenty of people in the comments joked that, yeah, they know better than to poop in a pool, there's more to it than that, Kathryn Boling, MD, a primary care physician at Baltimore's Mercy Medical Center, tells Health.
The dangers of swimming in a pool when you have diarrhea
Swimming in a pool when you have diarrhea "is a risky thing to do because you can have diarrhea for a lot of reasons, some of which are contagious," Dr. Boling says. The CDC points out that the average swimmer has about 140 billion microbes of poop lurking on their bodies, and that's not necessarily something that you'll see, she says. "You could have some bacteria or virus on your anal area that washes out into the pool," she says. Other diarrhea-causing bugs you could harbor besides Cryptosporidium include the bacteria E. coli and giardia, a parasite.
Other people swim in that water, and some will accidentally swallow it or get it into their nose and eyes, which can cause them to get infected, too, she says. And, unfortunately, Dr. Boling points out, "chlorine can't neutralize everything."
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Jamie Alan, PhD, associate professor of pharmacology and toxicology at Michigan State University, agrees. "Certain causes of diarrhea like parasites need high levels of chlorine to kill," she tells Health. "Average pools may not have those levels of chlorine."
And, of course, it can be tough to control your bowel movements if you have a bad case of diarrhea. If you're struggling with watery poop and happen to have an accident in the pool, it's not only gross—it's unsanitary.
Ultimately, doctors agree that if you have diarrhea, it's really best to sit out swimming in the pool until it completely clears.
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