Do Parasite Cleanses Work?

If you type "do parasite cleanses" into Google, it finishes the question with "hurt," "make you tired," "cause diarrhea," and "need a binder." There's a whole subreddit for people doing them, r/ParasiteCleanse, with posts titled "Help please! Are these worms?" and "UPDATE after 1 year of cleansing." The kits are capsules or drops, often built around wormwood, black walnut hull, and clove, and the videos selling them tend to end with a close-up of the toilet bowl.

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There's no evidence that these kits get rid of parasites. A Cleveland Clinic article on them says it flat out: "no scientific evidence shows that these so-called 'parasite cleanse diets' actually work." What people photograph in the toilet is most likely mucus and lining from their own gut. And if you really do have a parasite, a doctor can find out which one with a simple test, and the treatment is usually a pill or two.

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What's coming out in the toilet?

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A lot of cleanses contain strong laxatives. The Missouri Poison Center (the state's 24-hour poison hotline) explains that these laxatives "stimulate the colon and may cause the lining of the colon to shed," and that "this lining can be long and ropey," which looks a lot like a worm. Seeing it makes people keep going, since they take it as proof of an infection. The mucus you're losing is supposed to be there, though, because your intestines "need a healthy amount of mucus to sustain their natural microbiome" (the trillions of bacteria living in your gut).

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Laura Nabarro, a consultant parasitologist (a doctor who specializes in parasites) at a London hospital, told Vice that the "worms" people think they're seeing are "actually mucus strands or undigested organic matter," which "can be easily distinguished when examined under a microscope."

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The name "rope worm" comes from a paper posted online in 2013 to arXiv, a site where researchers can share papers without peer review (the step where other scientists check the work before it's published). Its authors wrote that rope worms "have been discovered as a result of cleansing enemas," that they move around by "utilizing jet propulsion," and that the adult stage "looks like a tough string of mucus about a meter long." They also admitted that their data "is not sufficient to identify the specie."

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Real worms mostly don't look like that anyway. The Missouri Poison Center points out that most of the parasites people pick up in North America (e.g., Giardia, Cryptosporidium, and Cyclospora) never become a worm you could see at all. Pinworms are the exception, and even they're only 6 to 13 millimeters long (about a quarter to half of an inch).

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What's in the bottle?

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ParaGuard, one of the kits that went viral on TikTok, costs about $37 for a bottle of 90 softgels. The label lists fennel seed, pumpkin seed, wormwood, garlic, clove bud, peppermint, oregano, green black walnut hull, marshmallow root, and slippery elm. Its product page never claims to kill anything. It says the herbs "have traditionally been used to support digestion and microbial balance."

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Companies that do promise to kill parasites get letters from the FDA (Food and Drug Administration), because a product that claims to treat a disease counts as a drug, and drugs have to be approved before they're sold. In 2020, the FDA sent one of those letters to a brand called Humaworm and quoted its own FAQ back to it. When a buyer asked "I have not seen any worms. Is it working?", the answer was "Yes, if you're taking HUMAWORM as directed, it's working," since "70% of parasites are microscopic." A buyer who asked why they felt like they had the flu was told "This is from your body detoxing." The same site claimed that "90% of us ALREADY ARE" infected. And when inspectors visited, they watched an employee scoop the powder into bags "with ungloved soiled hands."

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Supplements don't need approval before they go on sale, and Nebraska Medicine notes that parasite cleanses in particular "are not tested to see if they work or if they're safe." Peter Mannon, a gastroenterologist (gut doctor) there, warns that colon-cleansing products "can be contaminated by pathogenic bugs or toxic compounds like lead, mercury or arsenic." Wormwood contains a chemical called thujone that the Missouri Poison Center says "may be toxic in very large amounts," and the center adds that wormwood's "ability to specifically fight parasites is also unknown." Some cleanses act like laxatives, and Nebraska Medicine warns that with enough diarrhea "you can be at risk for kidney injury."

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Can any of it kill a parasite?

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Some of it might, in the right situation. The Missouri Poison Center says that "some of the ingredients on their own may truly be anti-parasitic," and a couple of small studies back that up. In Nigeria, 60 children whose parasites had been confirmed under a microscope got one dose of either dried papaya seeds mixed with honey or honey alone. A week later, 23 of the 30 kids who got papaya seeds had clear stool tests, against 5 of the 30 on honey. The researchers called it a pilot study and asked for larger ones comparing papaya seeds to standard medicine. In a study in rural China, 9 of 12 people with a confirmed tapeworm passed the whole worm after eating pumpkin seeds, though it took an average of about 14 hours. Adding an extract of areca nut (a different plant) cut the average to about 2 hours.

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Abhay Satoskar, a pathologist who studies parasites at Ohio State, doesn't rule the plants out either: "many effective drugs that we use today were originally discovered from natural products." What he objects to is the bottle. An FDA-approved drug has to show "batch to batch consistency," so every pill has the same thing in it, while an herbal blend can change with the season and the supplier.

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Both of those studies started with people who had a diagnosed parasite, and both tested one ingredient against one kind of parasite. A cleanse is the opposite setup, a mix of ten herbs taken for weeks by someone who doesn't know whether they have anything at all.

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Do you actually have parasites?

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Probably not. "It's unlikely that the average person is walking around with active parasites in their gut," Mannon says, and even among people who come in with diarrhea, "most test results are negative for pathologic parasites."

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Google finishes "grinding teeth at night" with "parasites" and "worms," and Vice collected the list influencers use: "Abdominal pain, bloating, gas, brain fog, teeth grinding, anxiety, constipation, insomnia and acne." Satoskar says that symptoms like "eczema, mental fog, teeth-grinding, tiredness" are "broad, nonspecific symptoms that are associated with many diseases." Taking a cleanse for them leaves whatever is causing them unchecked, and the Missouri Poison Center warns that self-diagnosing "could delay important healthcare."

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Parasites in the US are real, though. The CDC (Centers for Disease Control and Prevention, the US government's public health agency) says that pinworms "are the most common worm infection in the United States," mostly in younger kids and the people who live with them. Giardia, a single-celled parasite you usually get from contaminated water, makes "more than 1 million people" sick in the US every year, and it shows up as diarrhea, not as anything you'd spot in the toilet. According to Satoskar, if you live in the US and haven't traveled somewhere with parasites in the food and water, "the chances are low that you need to clear your body of intestinal parasites," with pinworms as the exception.

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If you've seen "do parasite cleanses kill cyclospora" in your search bar, Cyclospora is one of the parasites that the Missouri Poison Center lists as never becoming a visible worm, so there'd be nothing in the toilet to check, and Food Poisoning vs a Stomach Bug covers how to tell what you've got.

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What should you do if you think you have one?

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See a doctor, and tell them where you've traveled and what you've eaten. If you've actually seen a large worm, the Missouri Poison Center calls that "a sign to see a medical provider right away, not to continue with a natural cleanse." American Family Physician, the journal of the main group of family doctors in the US, says parasites "should be suspected in those who present with diarrhea lasting more than seven days." A doctor will usually order a stool test (checking your poop under a microscope) or a blood test. Parasites don't show up in every sample, so the CDC recommends "three or more stool samples, collected on separate days."

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Pinworms are the easy one. The main symptom, according to the CDC, is "itching around the anus," and the most common way to check is "the 'tape test'." Satoskar describes it as pressing clear tape to the skin around the anus, "especially at night," to catch the worms or their eggs. The CDC lists three medicines, and one of them, pyrantel pamoate, "is available without prescription." You take a second dose two weeks after the first, because the medicine kills the worms "but cannot kill eggs," and everyone in your house gets treated at the same time.

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For most other parasites, Cleveland Clinic's dietitian Beth Czerwony says, "In many cases, it's just one dose, and then you're done," and your doctor will retest you afterward to make sure.

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What about ivermectin and fenbendazole?

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Google also finishes "ivermectin parasite" with "cleanse," "protocol," and "die off symptoms." Ivermectin is a real antiparasitic drug that's approved for people, at specific doses, for specific infections. The versions people buy online are often made for livestock, and the National Capital Poison Center (one of the country's poison control centers) warns that they're "meant for animals that weigh several times more than humans, which can lead to an overdose." In one case the center describes, a man took two tubes of horse ivermectin in 12 hours, and "each tube contained enough medication for a one-ton horse."

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Fenbendazole is an animal dewormer that has spread online as a cancer treatment. The American Cancer Society notes that it's "intended for use in animals only," that the FDA "has never approved fenbendazole for humans for any purpose," and that liver damage has turned up in the few published cases of people with cancer who took it.

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