borax sick dog

Why you should never use borax for pest controlWe were shocked recently to read a veterinarian’s DIY “all natural” solution to kill fleas in a home. She recommend sprinkling borax on couches, carpet, chairs, and anywhere there was a flea problem. What caused this educated professional to give such very bad advice? Sloppy research. The internet is full of really bad advice, especially when it comes to “harmless home remedies.” Borax does not kill fleas. Sprinkling borax willy-nilly around a house is not harmless, particular if one has pets or small children. Ready for a well researched answer to the borax question? Read on.

First, let’s use words carefully: Boron is a naturally occurring element that is mined and processed into-

Borax (sodium tetraborate decahydrate), a water soluble laundry booster, and

Boric Acid, an ingredient in pest control products

Borax and boric acid come from the same element, but have different properties.

Second, the words “naturally occurring” apply equally to boron as to uranium and asbestos–other naturally occurring elements. “All Natural” and “Naturally Occurring” do not mean non-toxic. While boron is in a totally different toxicity class than asbestos and uranium, the comparison is made to help you avoid the trap of unscrupulous marketeers who use the phrase “all natural” as a synonym for “good or healthful.”

naturally occurring elements

The Facts About Borax

Borax powder has low toxicity to humans. It is in fact, a really good laundry booster and does a fabulous job of cleaning sinks and tubs. Many of our staff regularly use borax powder diluted in water as recommended by the manufacturer and listed on the box: as a laundry booster and general cleansing agent. While low in toxicity to humans, borax powder should not be inhaled, ingested, or left in contact with the skin or eyes. According to the CDC, borax exposure may cause irritation of the skin, eyes and respiratory tract, and nose bleeds and breathing difficulty. Ingestion of borax powder is associated with nausea, abdominal pain, and diarrhea. The International Chemical Safety Card for borax specifically recommends preventing the dispersion of borax dust and that pregnant women especially should avoid exposure.

Knowing this, why would anyone think that sprinkling borax powder around the house is a good idea? No one should breathe this stuff! Yet, that’s exactly what pets will do when snuffling around a borax dusted house. Children may also accidentally inhale borax powder and become ill. The only organisms that borax powder won’t bother are insects. Borax powder will not dehydrate insects, nor will insects willingly eat borax powder–that’s plain silly.

Keep borax powder, where it belongs…in the laundry room. Use it as directed, always diluted with water or made into a paste.

borax for laundry

More Facts, Less Confusion about Boric Acid

Recall when we said to use words carefully? Many of the misconceptions about borax as an insecticide come from the fact that both borax and boric acid are derived from the same element, boron. However these chemicals have different properties. Boric acid and sodium borate salts are active ingredients in pesticides. They are harmful to pests and are ingredients in many baits and other pest control products. In baits, boric acid is combined with other ingredients that insects find tasty. Boric acid acts as a stomach poison and may also have some toxic effects on the nervous system of insects. In addition to being stomach poisons, most borate salts are also abrasive to insect exoskeletons.

The boric acid technical fact sheet from the National Pesticide Information Center states:

Acute ingestion of boric acid or borate salts in humans has rarely led to severe toxicity. Commonly reported symptoms include nausea, vomiting (often with blue-green coloration), abdominal pain and diarrhea (which may contain blood or have a blue-green color). Other less commonly reported symptoms include headaches, lethargy, weakness, restlessness, tremors, unconsciousness, respiratory depression, kidney failure, shock and death.

In other words, don’t eat products containing boric acid and keep them out of reach of children and pets. Boric acid is categorized as having low toxicity to humans, but it can still make you sick. Always follow the label when using products containing boric acid or any other pesticide. Remember, if a product isn’t toxic, it won’t kill pests! So if you want to kill fleas, ants, cockroaches or other pests you will need toxic products. Use as directed to protect yourself and your family.

 Cockroach feeding on bait containing boric acid

It was difficult to film a cockroach feeding on bait containing boric acid because Thrasher Termite & Pest Control technicians applied the bait in an area inaccessible to children and pets… and cameras!

borax sick dog

Keep your pets and kids safe. Leave borax in the laundry.

Thrasher Pest ID

Text pest photos to 408-354-9944
The better the photo, the better the identification!


  1. Pam May 8, 2014 at 9:28 am - Reply

    I used borax on my carpets before I read this. My dog has had a nose bleed everyday for 5 months since using it.

    • Buzz May 14, 2014 at 3:55 pm - Reply

      Thank you for sharing your story. Hopefully, it will prevent another pet from experiencing the same problem. Many Thrasher staffers have dogs and/or cats. We wish you and your pup the best.

  2. Becky March 10, 2016 at 8:30 am - Reply

    This is just propaganda so you don’t lose business. Just like any pest control pets should be removed for a period of time. Borax does in fact kill fleas. I sprinkled it all over my floors, let it sit for 8 hours and then cleaned it all up. The infestation was reduced by more than 75%. A second 8 hour round got the rest. When the cats returned they had no issues from potential residue.

    • Garrett March 11, 2016 at 11:09 am - Reply

      We aren’t worried about losing business. We believe that providing well researched information will assist consumers in making good choices. We often publish DIY pest control tips, but only after evaluating their efficacy. In your situation, credit your vacuum for decreasing the flea infestation. Vacuuming alone is a very effective flea control measure and won’t hurt your pets. We stand behind our critique of using laundry borax for flea control. Laundry borax is not the same as boric acid and it does not kill fleas. Regarding it’s potential for harm, we’ll let the manufacturer speak for itself. The following text was taken directly from the Material Safety Data Sheet provided to OSHA by the manufacturer of 20 Mule Team® Borax Natural Laundry Booster.
      EYE CONTACT: Direct contact with dusts may cause severe irritation with redness, pain, blurred vision, and possibly corneal injury.
      SKIN CONTACT: Non-irritating to intact skin. Absorption through large areas of damaged skin may produce symptoms similar to those following ingestion.
      INGESTION: May cause gastrointestinal disturbances such as headache nausea, vomiting, abdominal pain, and diarrhea, with delayed effects of skin redness and peeling.
      INHALATION: Dust may cause mucous membrane irritation with coughing, dryness and sore throat.
      CHRONIC HEALTH EFFECTS: No chronic health effects are expected from the intended use of these products or from foreseeable handling of them in the workplace. Nonetheless, the following effects have been reported for a component, sodium borate, and boric acid. Sodium borate upon entry into the body becomes boric acid.
      Sodium Borate: Sodium borate and boric acid interfere with sperm production, damage the testes and interfere with male fertility when given to animals by mouth at high doses. Boric acid produces developmental effects, including reduced body weight, malformations and death, in the offspring of pregnant animals given boric acid by mouth.”
      Read the entire Material Safety Data Sheet HERE.

  3. John F April 9, 2016 at 2:52 pm - Reply

    I decided to test how effective borax is for killing fleas. Ordered a pack of 20 Mule Team from Amazon and sprinkled some in a jar covering the entire bottom.

    I then caught several fleas that were on my cat and placed them inside the borax jar. Five days later they are still jumping around. Borax obviously doesn’t work and if anyone has doubts they can try this themselves. Stupid old wives tale.

    • Buzz April 15, 2016 at 1:49 pm - Reply

      You’re brilliant. Thanks for the confirmation.

  4. MaryM April 15, 2016 at 2:56 pm - Reply

    Ok for the lady whose dog had a nose bleed did you ever consider cleaning the carpets 5 months is a long time

    • Buzz April 15, 2016 at 5:11 pm - Reply

      The dog’s nose bleed is consistent with the irritation of the mucus membrane. Pam doesn’t state that she did not clean the carpet for 5 months, only that the nose bleed continued for 5 months. Perhaps time elapsed before she realized the probable cause of her pet’s nose bleed. Perhaps she did vacuum the borax right away. The point isn’t Pam’s housekeeping skills, the point is that laundry borax can be as harmful as it is ineffective for killing fleas. Please do not misuse this otherwise very useful product. (Nothing makes the tile shine like borax!)

  5. Pace July 5, 2016 at 9:24 pm - Reply

    your definition is lacking…. this is straight from the United States National Library of Medicine: Boron is used for building strong bones, treating osteoarthritis, as an aid for building muscles and increasing testosterone levels, and for improving thinking skills …

    If you are going to give a report on a specific “mined” mineral…. Don’t leave out the good and total details….

    Your aguement is involving different substances….Borax Laundry Soap is different from Boric Acid….

    Really??? You compare Borax Soap to “uranium and asbestos” What are you actually trying to sell???
    “unscrupulous marketeers who use the phrase “all natural” as a synonym for “good or healthful.” Such as … the United States National Library of Medicine, on Boron.

    “Recall when we said to use words carefully? You should practice what you preach, and do some indepth research before speaking out in regaurds to any “element”.

    With what you have written, and attempted to have your readers believe based on only what you have written, discussed and defended….well… I know, and so should everyone else, you cant believe everything everyone says, on the internet, because you never know thier motives, and besides, some people just want to seem smarter than they are. I don’t need anyone to take my word for it, they can look up the information I have given through reputable sources such as : The United States National Library of Medicine.

    • Buzz July 7, 2016 at 2:52 pm - Reply

      Thank you for proving our point about reading carefully. This post is about using laundry borax as a home (mis)treatment for fleas. We are not for or against boron– only “for” good science. Regarding the United States National Library of Medicine, here is a link to the discussion of boron as a dietary supplement–not as a flea treatment. You ask what we are defending. We are “defending” product labeling. The label is the law. Don’t use laundry borax to kill fleas. It is ineffective and may prove harmful to your pets.

  6. SusanD August 6, 2016 at 9:16 am - Reply

    Thank you for bringing science to the internet, otherwise known as the world’s largest collection of outrageous urban mythology, ignorance, and uninformed opinion. It is disturbing to see the virulence of opposing posts here — people want so much to believe in fairy tales I guess.

    YES you are 100% correct that Boron is just as “natural” as uranium etc. The FDA has repeatedly looked at the topic of regulating the word “natural” in food labeling — and every time, they simply give up! Basically everything in nature is by definition natural, so if your cereal box contains wheat, oats, sand and gravel, it is 100% natural. Not yummy, but it is natural by any dictionary definition.

    Ignorance persists. I see the word “borax” thrown around by people who clearly think it is the name of the chemical element boron. I see people equating laundry Borax with boric acid. Basically, science education in the US is so lame and our society so proudly ignorant, they would rather quote some stranger on Facebook than actually go to school or read a book.

    I fear our society will poison itself with “natural” stuff of one kind or another, thinking the whole time that they are brilliant, using social media as an echo chamber to tell them repeatedly they are right because it feels so much better than actually knowing facts.

  7. Frank October 2, 2016 at 6:13 pm - Reply

    Arent ant baits filled with Sodium Tetra borate Decahydrate (Borax)??

    • Buzz October 3, 2016 at 1:20 pm - Reply

      The formulation of some ant baits include sodium tetraborate decahydrate mixed with other ingredients that are tasty to ants. Sodium tetraborate decahydrate is the same active ingredient in laundry borax, but when included in insect bait is different in consistency from laundry borax. Other ant and insect baits use boric acid (Boron hydroxide or Boron trihydroxide) as the active, toxic ingredient.

  8. Valdoria February 9, 2017 at 7:13 am - Reply

    This article just goes to show that you have to try things for yourself and get the quantitative analysis as all “science” is bias based on the focused outcome.

    I just tried Borax for the first time on my little dog. She cannot use flea control as those give her seizures as she is very reactive. When I use the shampoo to kill fleas it makes her sickly and only a few fleas come off.

    Today I tried mixing 2 tablespoons into hot water, about 22 ounces. I then shook it up a lot, it tends to clump so I continued to shake it up.. and then when it was cooled down a bit, I put my little girl in the tub and just poured this onto her fur slowly, letting it set into each area. Immediately a flea hopped onto my arm and then I started to see a few come off from all over. Then I started to run the shower and let it warm while she sat in the tub, waiting a minute or so for the borax solution to work. Then I put her in the shower and washed her with a regular gentle dog shampoo. More fleas came off and she was washed and rinsed well. Now she is laying in the sunroom warming while she dries completely and seemingly much happier with less fleas. Definitely less toxic than the other options which are poison. I cannot believe some companies tell you to feed your dog poison pills to kill fleas. That is so bad for the liver.

    • Buzz February 10, 2017 at 2:03 pm - Reply

      We can’t disagree more with your statement, “This article just goes to show that you have to try things for yourself and get the quantitative analysis as all ‘science’ is bias based on the focused outcome.” When it comes to chemicals and pesticides, trying things for yourself can be dangerous, this is why we ALWAYS refer to the product label and Safety Data Sheet. We advocate for correct identification of the pest in question, pest prevention, modification in cultural practices, and application of the most targeted, least toxic material to control the pest. We do not recommend ignoring product labeling. We sincerely hope that your pet experiences a good outcome; however, your anecdote should not be construed as science: there was no control subject, the data set is too small to allow for quantitative analysis, etc. Because laundry borax (Sodium Tetraborate) specifically states that it can cause skin irritation, we respectfully submit that this otherwise wonderful cleaning product SHOULD NOT be used as a DIY flea bath.

    • MoonLi July 12, 2017 at 5:28 pm - Reply

      Don’t wash your dog with borax😵😵😵😵

  9. Jeff Cornell April 3, 2017 at 12:44 am - Reply

    You seem foolish. I trapped about a dozen fleas in a container and put out 20 mule team Borax at the other end…I was careful not to sprinkle it on them and not make direct contact so as to not skew what happened and then left it for a day when I was out of town. When I returned the next evening I looked and all the fleas were dead. I only put a sprinkle and barely even visible amount. They probably came into contact with it as one point or another. Borax absolutely works. I have no dog in the fight and if it didn’t work I would be the first to say, but it worked.

    You, however do have a dog in the fight and seem biased because you are an exterminator and have a vested interest in DIY pest control to NOT be effective. That is the equivalent of a mechanic telling you that you cant change your own oil…nonsense. Do your own experimentation with captive fleas and you will see that it works. I didn’t even sprinkle directly on them. So I imagine if you did they would die shortly after.

    • Buzz August 18, 2017 at 12:52 pm - Reply

      You, sir, seem not like a scientist. Those who have performed the exact same test following the scientific method have had vastly different results. There is no fight here. We readily advocate the use of the least toxic product to get the job done. We use products with very low toxicity to people and pets. But as a LICENSED company we will only use product according to the label instructions. You may do what you wish at your own risk.

  10. S June 10, 2017 at 6:44 pm - Reply

    Dear author,
    I actually read all the comments, and I’ll try not to sound like a PhD. I don’t think your intentions are to scuttle a cheaper product to sell your own. You seem very well read, and interested in facts. Alot of the contention you will receive from stating what you are stating, will be from the general suppression of natural cures by big pharma. I believe it is legitimate with borax. However, I think speeding any salt (which is what it really is) around your floors dry is plain ignorant. However, again, it does kill fleas, as little as a quarter cup in a gallon of water and they are toast pretty darn quick. I used 1/2 cup borax, and 1 cup mean green to a gallon of water in carpet shampooer. (I know the soap itself will kill fleas). This is a different level. As dumb as it is to sprinkle it dry, it still not as bad respiratory wise as diatomaceous earth. And as irritating as borax can be to someone or pet who is sensitive to it, it is not chronic, only immediate, it is shed pretty easy. I use a couple table spoons in my dogs’ rinse water, no issues. And it kills the fleas, have had very expensive shampoos just make them curl up and start flipping again 20 mins later.

    • Buzz August 18, 2017 at 12:58 pm - Reply

      Thank you for your thoughtful reply. Again, we do not advise using any product in a way that is contrary the instructions on the label. Those instructions were written after testing. You may choose to ignore product labeling, however as a licensed company, we may not, nor will we recommend others do so.

  11. Samantha Rose October 18, 2017 at 6:28 pm - Reply

    Buzz: are you married? and are you female? :)) because I believe I just fell in love with your ability to communicate and decipher between truth and deflection (and because I’ve decided I should have been born a lesbian because I rarely find men intellectual anyways) sincerely the best information I have found in four months of researching in my spare time has come from your input here! Thank you for declining to entertain the expected ridicule and backlash as well! My personal circumstance isn’t relevant I suppose so just know that you saved two very loved female canines from snuffing and huffing my pitiful attempt to ease my paranoia. I don’t live in your region so Ill have to find someone local, and hopefully your like minded professional tomorrow….**leaves messaging to vacuum floor again =}

    • Buzz October 20, 2017 at 1:46 pm - Reply

      Thanks for the note. It made me smile and quite gratified that your dogs won’t be inhaling laundry borax anytime soon!

  12. Diane October 28, 2017 at 9:52 pm - Reply

    It’s interesting that even such a banal topic brings out fighting emotions on the Internet! *sigh* I got here while trying to figure out the difference between borate, borax, and boric acid. It seems there is a difference–they’re not just different names for the same thing.

    For what it’s worth, I’ve been using a borate crystals product, Dr. Goodpet brand (but there are other brands that seem to be the same substance), and it’s the only thing that finally conquered the fleas in this fully carpeted apartment I’m in. I fought them for months with other natural products, with some success, but this finally broke the life cycle, as it apparently goes down to the root of the carpet fibers (you brush it in) and doesn’t get vacuumed up due to its texture. It kills eggs and larva which are impossible to vacuum up completely. I’m using it as labeled and I feel it’s safe. I’ve reapplied it once to areas the cats are mostly in, but otherwise it’s supposed to last a year. Very relieved to have won the war!!

    • Buzz November 8, 2017 at 3:39 pm - Reply

      We stay away from product recommendations, but I wanted to share your comment for one important reason. You are using a product LABELED for the way you are using it and you are following the label directions! Glad to hear your success story.

  13. […] Borax, Fleas, and Misconceptions – Pest Control |Termites – Borax does not kill fleas. Sprinkling borax willy-nilly around a house is not harmless, particular if one has pets or small children. The truth about borax. […]

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