A persistent health fad that often involves squirting water up your rear and into your colon doesn’t sound too pleasant, and experts say it’s not good for you either.

The colonic irrigation and other “colon cleanses” that claim to clear toxins out of your system, whether with water going up or pills going down, can cause all sorts of health problems without any evidence that they help. In addition to the danger that irrigation will puncture the colon because too much force is used, or cause a bacterial infection or inflammation, the unproven pills could create imbalances in electrolytes and gut bacteria, dehydrate you or damage the kidneys, Time magazine notes. People have also reported side effects of vomiting and diarrhea.

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“It’s a very popular subject for patients to bring up,” Dr. Brooks Cash, a professor of medicine at the University of South Alabama, told Time. “A lot of people think it will help with weight loss.”

There are times when pumping something up the butt has a medical benefit, as when trained doctors use an enema to relieve a severely constipated patient or to clear away waste for a better view during a colonoscopy. But on an everyday level, there’s no buildup of waste and mucus on the inside of your gastrointestinal tract that you need to clean out, Bustle reports.

“It's nonsense, for several reasons, the biggest of which is that the colon is already self-cleaning,” the publication says. “This is a complete fabrication with no anatomic basis.”

The body already has processes for clearing away toxins. “Your gut — as well as your liver, kidneys and immune system — are all designed to keep your body free of bacteria and harmful agents,” Time says. “Pumping yourself full of so-called cleansers, either orally or anally, is more likely to throw off than bolster your internal decontamination processes.”

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