Diatomaceous Earth and Fleas on Cats

Diatomaceous Earth and Fleas on Cats

You may have heard about diatomaceous earth as a flea treatment and are wondering what exactly is diatomaceous earth. Diatomaceous Earth is basically fossils of diatoms that live in water. It is soft and fine like talc as well as porous (I use it to make essential oil air fresheners because it holds the scent for so long). Diatom fossil remains form a heavy layer on the floor of lakes, rivers and oceans. Their skeletons are made of silica, a natural substance, and silica is what makes up Diatomaceous Earth.  Diatomaceous earth and fleas on cats (or any animal) don’t get along well.  Diatomaceous earth is a toxic substance to small insects like fleas.  It will rid your pet of these nuisances.

There are many uses for diatomaceous earth beside flea control such as:

  • beauty masks
  • internal parasite control
  • water purification
  • body detox
  • improves joint, bone and ligament health
  • cleans nails, teeth, and skin
  • …and much more

Diatomaceous earth as flea control

Diatomaceous Earth and Fleas on Cats

Diatomaceous earth has become widely used. Food grade diatomaceous earth is safe for pets, livestock and humans (read Is diatomaceous earth safe for cats below). The product is easy to use and the food grade product contains no chemicals. I administer once a month during the summer as with any other flea product. I live in Connecticut so during the winter, I don’t see any fleas. You might live in a different area or have seen fleas during the winter months but I check them every so often with a flea comb and I’ve aways come up flealess!

Does diatomaceous earth kill fleas?

Yes, it does.

Does diatomaceous earth really kill fleas?

Yes, it really does!

How does diatomaceous earth kill fleas?

Diatomaceous earth is a fine powder made from crushed diatom fossils. Diatoms are a type of fossilized phytoplankton that has razor sharp edges like shards of glass. The sharp edges cut the fleas exoskeleton and the insect dehydrates and eventually dies.

Will food grade diatomaceous earth kill fleas?

Yes, food grade diatomaceous earth will kill fleas. Both food grade and non-food grade diatomaceous earth have the same razor-like edges. The difference between food grade and non-food grade diatomaceous earth are additional harmful chemicals in the non-food grade product. Therefore it is important to always buy food grade diatomaceous earth.

Does diatomaceous earth kill flea eggs / larvae?

No, it does not. That is why it is important to do a follow-up treatment within a week if you have a current infestation as the fleas will need to hatch first. If you are only using it for prevention, then once a month is sufficient from my experience.

How fast does diatomaceous earth kill fleas?

48 to 72 hours

Is diatomaceous earth safe for cats?

Diatomaceous Earth and fleas on cats
Diatomaceous earth powder

Yes, both topically and internally.  I have been using it topically for almost two years on my cats.  I have also been putting it in their food a couple times a week to use as worm prevention.  You can read about diatomaceous earth as a dewormer here.

Both the CDC and the National Pesticide Information Center have fact sheets on Diatomaceous Earth. The CDC fact sheet for Amorphous (Freshwater) Diatomaceous Earth states that there are no known chemical dangers and no short-term effects from exposure (there are long term effects). There is one phrase of caution “harmful concentration of airborne particles can, however, be reached quickly when dispersed” which is true.  However, I’ve been using this stuff for a while and my assumption is this is in relation to large quantities.

The National Pesticide Information Center states that amorphous diatomaceous earth is quickly eliminated from lung tissue whereas crystalline diatomaceous earth is smaller and build up in the lungs. The product we use is amorphous (or freshwater) and is food grade. Crystalline is not food grade and is usually used in pool treatments and pesticides. Click here to read my food grade diatomaceous earth reviews and be sure to buy the proper product.

How to use diatomaceous earth for fleas on cats

Step 1

Wear gloves as it is very drying.  Diatomaceous earth is very drying (it is a mild abrasive) and will dry out both your cat and your skin. Sometimes I don’t wear gloves and notice little areas of dry skin on my fingers afterward. To avoid this wear gloves.

Step 2

Diatomaceous earth and fleas on cats
Zoli after his dusting

I take a spoon and just put about a quarter teaspoon on their lower back and rub it in gently so as not to create too much dust. A couple sprinkles from a salt shaker and a good rub will work well too.  The cat’s movement will spread it around enough and the fleas won’t sense a topical chemical like commercial flea products so they will walk right through it and commit suicide. I go about halfway up the back because I don’t want to get it in their eyes. It is not good for the mucous membranes (eyes and nose) so but sure to apply it inside away from any breeze.

I did get it in my eyes once.  The only thing that happened was my eyes got very itchy, irritated and red for about 4 hours. It was uncomfortable but I didn’t die or go blind.  Lol.  That’s not to say I would take a whole bag and dump it on my face because that would probably be much worse.  Just take your time, be careful and you and your cat will be fine.

REMEMBER: Less is more!!!  You don’t need to change your black cat into a white one.  Very little goes a long way.  Actually, if you use too much, the fleas will avoid the area and not die.  A light dusting is sufficient.

Step 3

If you have carpet, you should vacuum first and then apply a thin layer of diatomaceous earth and vacuum it up after about 72 hours.  I don’t have any carpets in my house. I have all wood floors so I’ve never had to treat the floors.  A word of caution. DE is hard on vacuums so a shop vac is your best best.

Step 4

Diatomaceous earth and fleas on cats
Coconut Oil

I give the diatomaceous earth a few days to do it’s job and then apply coconut oil to their fur because of the drying effects. I just melt a little in my hands (it has a very low melting point) and rub it on them. You can use olive oil too if you don’t have coconut oil. My cats like both oil and coconut oil and it is good for them. I do this for a couple of days. They will look a little greasy for a little while but it helps with the dry skin.

This is what I do for prevention but if they are infested then you need to reapply within a week. Since diatomaceous earth doesn’t kill flea eggs or larvae, you need to get the new batch of buggers once they’ve hatched.

Have you used diatomaceous earth before?  What is your experience with diatomaceous earth and fleas on cats?  Leave a comment below and let me know!  Cheers!


  1. Interesting stuff. I heard about diatomaceous earth a couple weeks ago for flea control on dogs. I did not know you could use it for so many human reasons too. And I didn’t realize there was such an important difference between food grade and non-food grade. Though I guess if you really think about it, the words food and non-food really say it all. Still, it’s nice to know the reasons behind all this. Next summer I plan to use diatomaceous earth for flea control on my dog. We don’t have fleas in the winter either. At least, I hope not!

    1. Thank you! Yes, it is very important to buy the food grade type otherwise you’ll have a bigger problem than fleas. When you start using it for summer flea control, start applying about a month before the warm months when fleas start to come around. Here in Connecticut, it doesn’t start to really warm up until the end of May so I start in the end of March/beginning of April when the cats start staying outside more and more.

  2. Hi Cat1574,

    First I want to ask you, is the product similar to boric acid? We had a flea infestation several months ago and went through the process of getting rid of these fleas. We used boric-acid at the time as well as using other tips from online to rid these buggers. Second, you have a great sense of humor, loved that! “commit suicide”. LOL! I enjoyed your website. I’ll be following you and check back for your new post. Have a great day!

    1. No, diatomaceous earth is nothing like boric acid. It is all natural and is made from ground up fossils which makes it super safe.

      Thank you!

  3. Thank you for this very informative in-depth article.

    I have never heard of diatomaceous earth or using it to kill fleas. I don’t like using harsh chemicals on my cat for flea control and this seems like a wonderful option.

    Where can you buy the food grade diatomaceous earth? Is it specifically labeled as a flea killer?

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