This popular cleaning ingredient is a great example of why "natural" doesn't necessarily mean "safe."
two cats and a dog in the laundry room, with one cat sniffing at the Borax box
Credit: Corinne Mucha

Preparing your spring cleaning checklist? No matter if you're cleaning your home or yard, you might've heard great things about borax.

Borax is a natural mineral that usually appears as a white powder and is used in cleaning products, household products, and insect repellents. However, these products are often poisonous to our pets and are among the top pet toxins.

That brings us to the crucial questions: Is borax toxic to dogs or cats? Or can we clean with this natural ingredient worry-free?

Unfortunately, borax is, in fact, toxic to both dogs and cats. And although it's considered natural, borax can cause harmful side effects in pets—and humans.

Is Borax Harmful to Dogs and Cats?

Borax is a go-to product when it's time to make your home sparkle and yard looking great.

A few common products borax is used as an ingredient include:

  • Toilet bowl cleaners
  • Laundry detergent
  • Pesticides
  • All-purpose cleaners
  • Paint

Considering its uses, you might wonder just how harmful borax is to your canine companion and feline friend.

"Borax, the soap used in the making of slime, has low risk to pets," says Heather Handley, DVM, Senior Consulting Veterinarian, Clinical Toxicology at the Pet Poison Helpline. "If ingested, self-limiting vomiting may occur. This might be more significant for smaller pets."

While borax may have a mild toxicity to pets, it's always better to be safe when it comes to your pet's health. So, whether you're using borax for cleaning purposes or recreational activities, it's important to know how it can affect your dog and cat … and you!

Our precious pets have stronger senses and sensitivities compared to us humans, which is why even certain flowers and essential oils can be toxic to our four-legged friends, especially cats.

If your dog or cat come into contact with borax, they may experience symptoms such as:

In severe cases of poisoning, borax can cause kidney damage, seizures, and death.

As for humans, the CDC states borax can cause irritation to eyes, skin, upper respiratory system and cause dermatitis, nosebleeds, coughing, and breathing difficulty upon contact. If ingested, borax can also cause nausea, abdominal pain, and diarrhea.

Considering its side effects, it might be best to avoid using borax and finding a safe alternative—especially if you have pets and children.

How Much Borax Is Toxic to Dogs and Cats?

"Any ingestion could cause an upset stomach and self-decontamination via vomiting," Handley says.

Handley adds that it "is not likely" that a dog or cat would be able to ingest the lethal dose of 974 mg/kg, or nearly 1 gram of borax per kilogram of their body weight.

Additionally, when it comes to humans, 5–10 grams (i.e. roughly one teaspoon) can be fatal to children and 10–25 grams for adults.

Is Borax for Fleas Safe for Cats or Dogs?

Have fleas wreaked havoc on your pet and home? If so, you might have read about borax being a solution to eliminating those pesky pests by applying it on carpets and furniture.

But how safe is it, really?

"As long as the cat or dog does not directly ingest the insect bait, then signs are not expected," Handley says. "If the bait was licked, then there would be a possibility for mild signs."

With proper precautions, you could keep a room off-limits to your pets while you apply borax powder on carpets and furniture and ensure it's safe by thoroughly cleaning it up. If that's not a suitable option, it might be worth considering other alternatives. (Also: please, do not ever apply borax directly on your pet as a flea treatment!)

Safer alternatives to flea treatment and prevention include:

  • Bathing your pet and using a flea comb to remove fleas
  • Treating your home via frequent vacuuming and washing pet bedding
  • Administering a flea medication specifically for your dog or cat, such as a spot-on flea treatment, oral medication, spray, shampoo, etc.
  • Using year-round flea prevention on your pet to keep them (and your home) flea-free

Treating your pet and home for fleas is never fun, but it is possible!

What to Do If Your Pet Licked or Ate Borax

Come to find your inquisitive dog or curious cat licked borax? Check to see if you can tell how much was ingested and rinse your pet's mouth. Rinse any other areas, like their skin or near their eyes, to prevent further irritation.

"Treatment is not usually needed unless the pet develops protracted vomiting," Handley says. "If a very large amount was ingested and the pet is not already vomiting, then a veterinarian should be consulted."

If you're unable to reach a vet, you can call 24/7 helplines including the Pet Poison Helpline at (855) 764-7661 or the ASPCA Animal Poison Control Center at (888) 426-4435.

When it comes to toxic cleaning products like borax, we recommend putting the item in a contained area that's out of reach to your pets and children or finding pet-safe alternatives. That way, you can keep your pets safe and home clean.