We all know there is a lot of misinformation on the internet. Touting diatomaceous earth as an effective or reliable internal parasite preventative or treatment is an example. The truth is, DE does not protect against or treat internal parasites.

What is DE?

DE, or diatomaceous earth, is a siliceous sedimentary rock containing the fossilized skeletal remains of diatoms. Diatoms are a unicellular algae, constituting much of the phytoplankton in the ocean. DE has a variety of uses, including as an abrasive, a filter, an anticaking agent, and an insecticide.

How does DE work as an insecticide?

DE works mechanically, rather than chemically, to kill insects. It has sharp, abrasive edges which damage the exoskeleton, and it dries out the insect by absorbing fats and oils from the cuticle of the exoskeleton, causing desiccation, dehydration, and death. It remains effective as long as it is kept dry [1].

This means that DE can be used to get rid of fleas, ticks, and mites in the environment.

DE kills insects, not worms

To review: DE kills arthropods by damaging their exoskeleton. Arthropods are defined as invertebrates that possess an exoskeleton, including insects and spiders.  Intestinal parasites like roundworms or tapeworms are not arthropods, and they do not possess an exoskeleton. This means DE’s abrasive action does not work on worms like it would on insects.

Besides, if DE was abrasive enough to kill worms inside your dog’s intestines, it would also be damaging your dog’s delicate intestinal lining, causing inflammation and irritation.

DE must be kept dry in order to work. The higher the moisture or humidity, the less effective DE becomes [2, 3]. This means that it will not be very effective inside the digestive system of an animal, which is obviously not dry.

However, studies have consistently shown no difference between DE and control groups [4, 56]. The science is clear: DE is not effective against intestinal parasites.

But even though DE doesn’t kill worms directly, it may help prevent the spread of worms indirectly by killing insects that can spread internal parasites [7]. Still, this doesn’t mean DE is killing the parasites itself, just getting rid of possible vectors of some parasites – like some roaches and beetles.

Safety concerns

Although DE is touted by many as 100% safe, that is not completely true. Excessive inhalation of DE can be dangerous and has been associated with lung cancer [8, 9]. Do not allow yourself or your animals to inhale DE or get it in or around the eyes.

While some owners recommend dusting DE on dog’s coats to prevent or treat fleas, ticks, or mites, this shouldn’t be done excessively or long term because it has been said to dry out the coat and irritate the skin.

Environmental concerns

Although DE is effective at killing insects in the environment, keep in mind that it is not selective in the types of insects it kills. While it might be good to use in your home or yard short term if you notice you have issues with fleas and ticks, using it indiscriminately may kill more beneficial organisms as well, including important pollinators like bees.


DE does a good job of killing insects in dry environments, which can be useful if you need to get rid of fleas or ticks. But its use for parasites end there; it is not an effective preventative or treatment for intestinal parasites. Please don’t rely on ineffective treatments – doing so would be allowing your dog to suffer unnecessarily, when there are safe and effective dewormers available that will get your dog healthy again much faster and much more reliably.