There is no reliable scientific evidence that diatomaceous earth kills parasites in humans. Despite widespread claims online, no clinical trials have demonstrated that swallowing food-grade diatomaceous earth eliminates intestinal worms or other human parasites. The FDA has not approved it for this use and has actively issued warning letters to companies marketing it as a “de-wormer.”
What Diatomaceous Earth Actually Is
Diatomaceous earth (DE) is a fine, chalky powder made from the fossilized remains of tiny aquatic organisms called diatoms. These fossils are composed mainly of silica. Under a microscope, the particles have sharp, jagged edges. When insects crawl through DE, those edges damage their waxy outer coating, causing them to dehydrate and die. This mechanical action is well documented for small arthropods like fleas, bed bugs, and ants.
The leap from “kills insects” to “kills intestinal parasites” is where the science falls apart. Insects have a thin, waxy exoskeleton that DE can physically abrade. Internal parasites like roundworms, tapeworms, and hookworms live in a wet, mucus-rich environment inside your gut. They have soft, flexible body walls that are nothing like an insect’s exoskeleton. The sharp-edge mechanism that works so well on dry insects has no demonstrated effect on parasites swimming in intestinal fluid.
What Animal Studies Actually Show
Proponents often point to livestock research as evidence that DE works internally. The results don’t support the claim. A University of Nebraska study fed diatomaceous earth to finishing cattle over 28 days and tracked parasite egg counts in their feces. At the start, 20% of steers in the DE group had detectable parasite eggs. After 28 days, that dropped to 2.2%. Sounds promising until you look at the control group: steers that ate no DE at all went from 11.1% to 0% parasite eggs over the same period. The cattle that received nothing cleared their parasites more completely than the ones eating DE.
This pattern repeats across similar livestock studies. Parasite loads naturally fluctuate with season, immune response, and diet changes. When DE groups don’t outperform control groups, the product isn’t demonstrating efficacy. And even if animal results were positive, the digestive systems of cattle and humans differ enough that you couldn’t assume the same outcome.
The FDA’s Position
The FDA does not recognize diatomaceous earth as safe and effective for treating parasites in humans. In 2019, the agency issued a warning letter to Earthworks Health, a company selling food-grade DE and marketing it as an “internal de-wormer.” The FDA stated that these health claims made the product an unapproved new drug under federal law. The letter also noted that the FDA has not evaluated the safety of adding DE directly to food, and that the agency is unaware of any independent expert determination that this use qualifies as “generally recognized as safe.”
Food-grade DE is permitted as an anti-caking agent in animal feed and grain storage, where it prevents insect infestation. That industrial approval is very different from approval for human consumption as a medicine.
Food Grade vs. Industrial Grade
If you’ve researched DE at all, you’ve seen warnings about buying the right type. Food-grade DE contains less than 1% crystalline silica. Pool-grade or industrial DE can contain 94% or more crystalline silica, which is genuinely dangerous to inhale or ingest. The World Health Organization recommends DE contain less than 2% crystalline silica to be considered safe for general use.
The distinction matters, but “food grade” doesn’t mean “safe to eat as a supplement.” It means the crystalline silica content is low enough that the product can be used around food products without contamination concerns. The label describes a manufacturing standard, not a health endorsement.
Risks of Ingestion and Inhalation
Most of the documented health risks of DE involve breathing it in rather than swallowing it. Even food-grade DE creates fine airborne dust when handled. Inhaling it can irritate nasal passages, trigger coughing, and cause shortness of breath. The amorphous silica in food-grade products is typically cleared from lung tissue quickly, and any inflammation is mild and reversible.
Crystalline silica is far more dangerous. It accumulates in lung tissue and lymph nodes rather than being cleared. Long-term occupational exposure to crystalline silica dust is linked to silicosis, chronic bronchitis, and significantly elevated risk of lung disease. A CDC risk assessment of workers in the diatomaceous earth industry found that at current permissible workplace exposure limits, the excess lifetime risk of developing silicosis was 75 per 1,000 workers, and the risk of dying from non-cancer lung disease was 54 per 1,000. Those numbers reflect decades of occupational exposure, not occasional home use, but they illustrate how seriously crystalline silica affects the lungs.
As for swallowing food-grade DE, there’s limited formal data on side effects because so few controlled studies exist. Anecdotal reports include constipation, bloating, and digestive discomfort. Because DE is essentially powdered rock, it passes through the digestive system largely unchanged. People with existing gastrointestinal conditions may find it irritating.
What Actually Works for Human Parasites
If you suspect you have an intestinal parasite, the effective path is a stool test followed by targeted antiparasitic medication. Stool analysis can identify the specific organism, whether it’s a roundworm, hookworm, tapeworm, or protozoan like giardia. Each type responds to different treatments, and a correct diagnosis makes a significant difference in outcomes.
Prescription antiparasitic drugs are well studied, widely available, and typically resolve infections within days to a few weeks depending on the organism. Over-the-counter options exist for pinworms specifically. Trying to treat a parasitic infection with an unproven remedy like DE delays effective treatment and gives the infection more time to cause damage, particularly in cases involving tissue-invasive parasites that can migrate beyond the gut.