Food grade diatomaceous earth (DE) – pluses and minuses

Food grade diatomaceous earth is a useful and natural way to control fleas in a multi-cat environment or, for example, for cat breeders. Diatomaceous Earth is dug from the ground as a soft rock and processed to be edible. It is regulated by a number of standards agencies such as the US Food and Drug Administration.

How it kills fleas

How, though, does it control fleas, parasites and insects? It can be sprinkled on the floor – carpeted or otherwise – and it kills fleas by cutting their external skeleton and desiccating them as they stick to their bodies and absorb internal fluids. As part of the flea’s life cycle the flea spends time on the ground. The flea also jumps on and off the host, which might be your cat. It is when the flea is on the ground that it is killed by diatomaceous earth.

Multi-purpose product

Perhaps the leading point about this product is that it is natural, i.e. no chemicals and it works in a physical rather than a chemical manner. The reason why it is made suitable for eating is because it is used to kill insects that migrate to animal feed.

Diatomaceous earth is a very, very fine powder which you buy in a tub. It is made from the sediment of fossilised algae. It is very high in silica because the cells of the algae that are fossilised are also high in silica. You will find diatomaceous earth deposits in many places. In the era of the ancient Greeks, they used the product to make bricks and blocks.

Food grade diatomaceous earth (DE) is used or can be used for treating cholesterol levels and constipation in humans and it can also be used to improve the health of skin and bones et cetera in people. It has a wide range of uses in industry such as cleaning up spills in the insulation businesses.

Food grade DE
Food grade DE. Photo: in public domain.


As mentioned, it contains silica at about 80%-90% by volume. It appears that veterinarians don’t have enough information to tell us whether there are side effects to its use. They do say that workers who work with diatomaceous earth on a daily basis can acquire lung problems and even lung cancer. And it can cause wounds when rubbed on the skin. This is because it contains silica which is sharp and it is the sharpness of these very fine particles which cut open the exoskeleton insects and kills them.

This information applies to people and therefore it would apply to people who use it to kill fleas. However, the amount that one uses to kill fleas and the infrequency of its use must make it harmless to people in this context provided it is used sensibly.

It is not advised to put DE on upholstery or mattresses because it can irritate human skin.

It seems that the biggest danger for somebody using DE for the first time is in applying it to liberally which can lead to inhaling it and it may cause skin dryness and therefore irritation. It may also irritate the eyes because it is abrasive.

Applied directly to a cat?

One veterinary website states that veterinarians generally advise against using the product to kill fleas. And they say you should not apply DE directly to a cat because there is a possible danger of causing lung damage if inhaled. That information comes from Dr. Jennifer Coates out of Fort Collins, Colorado, USA.

One issue with cats is that if you rub DE into a cat’s fur to kill fleas that are living inside the fur, your cat may ingest this diatomaceous earth when they groom themselves. This may conceivably lead to health risks. Although, food grade diatomaceous earth is eaten by cattle which is why it is food grade. Therefore, I would have thought that the risk is very low.

When applied around the home it can be effective the kill fleas. But vets advise that you obtain the advice of a pest control service to know how much to apply and where to apply it.

Kills adult fleas in 4 hours

Another factor is that the product only kills adult fleas and it doesn’t prevent their reproduction. This must limit its usefulness in controlling a flea infestation inside the home.

However, when a flea comes into contact with DE they may die in as little as four hours but it should be left on the ground for up to 48 hours to make sure that it is effective.

In general, it seems, that this product is not the most effective method of controlling a flea infestation.

If you do use DE they recommend 1/2 teaspoon of food-grade DE once daily with food for small dogs and puppies. I suspect that the same amount applies to cats. Although – and this is important – you must check with your veterinarian first because I am not a veterinarian and you will use this product at your own risk.

DE also kills ticks which is useful to know because ticks are a parasitical hazard to domestic cat will go outside and walk through long grass.

Vaccuum to remove flea eggs

If you are concerned about flea eggs being in your carpet (and I would recommend a hard floor to cat owners) you can remove up to 90% of flea eggs by vacuuming the carpet every other day. You might use DE on your carpet beforehand and then you can hoover up both the DE and dead fleas and any larvae.

Insecticides can be more dangerous

I have painted quite a negative picture of DE but that said it has advantages. The clearest advantage is that it is not a dangerous chemical. Insecticides are essentially strong poisons and dangerous. They are certainly potentially far more dangerous than DE.

There are considerable number of posts on this subject on the website. If you’d like to read and see more, please click on the links below.

Picture of diatomaceous mining published under creative commons Attribution License – by AlishaV

5 thoughts on “Food grade diatomaceous earth (DE) – pluses and minuses”

  1. Hi,
    I work for a company that sales diatomaceous earth and I was wondering if you would be willing to post a link to our page at By doing this your readers would be able to easily see where they could purchase DE as well as getting more information about its uses.

    If I don’t hear back from you before, I’ll be contacting you again next week.

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