How Toxic Is Borax to Cats?

We’ve all heard of the many uses of borax and how it doubles as a flea-killer for cats.

But have you ever thought about the dangers of this chemical? Dr. Angela Damant, D.V.M says you should as less than 5 grams of Borax is enough to kill a cat. That’s the weight of a credit card. 

So how exactly can you protect your cat from borax? And what should you do if your cat accidentally ingests some of it?

Keep reading on to find out!

What is borax?

Borax, also known as sodium borate, is a chemical made of boron, sodium, and hydrogen. This white powdery substance is a commonly used household product. It is found in many cleaning solutions and is also used in pure form for keeping ants or mice away.

The chemical is also added with the laundry to remove tough stains from clothes. Many areas that receive hard water supply use borax as it is alkaline and helps neutralize water pH.

How is borax toxic to cats?

Borax is often recommended as a DIY solution for a cat infested with fleas or mites. The instructions usually involve sprinkling Borax around the house, on the cat’s body, and even in their food tray or litterbox.

But what most owners don’t know is that just 5 grams of Borax can be lethal for cats if ingested. And the likelihood of that happening is very high since cats groom themselves a lot and will probably inhale and lick the chemical off their fur.

If your cat ever ingests borax, it can experience the following adverse reactions:

1. Respiratory distress

Borax is a mild lung and throat irritant. But if inhaled in large quantities, it can also result in respiratory distress. When this happens, your cat will become oxygen-deficient and start panting.

Their gums might turn blue, and some cats will also have foaming at the mouth. This is an emergency situation and can turn fatal if not immediately treated by a vet. So don’t wait if your cat shows even slight breathing issues after coming in contact with borax.

2. Kidney damage

After a cat ingests borax, it is metabolized by the kidneys. If the quantity is too high, their kidneys will be put under pressure and can suffer permanent damage or fail entirely.

Alternatively, if you treat your cat with the chemical in small quantities, the damage will take place over a longer period. In any case, look for signs like weakness, weight loss, excessive thirst, and bloody excrements to identify if your cat’s kidneys are failing.

3. Reproductive organ damage

Borax can be detrimental for your cat’s reproductive organs. After coming in contact with their genitals, the chemical can cause irritation and skin problems. Not only that, but it can also lead to deterioration of their internal reproductive system.

This will reduce the chances of your cat getting pregnant. You should also be careful using borax around pregnant cats as exposure can sometimes result in miscarriage.

4. Developmental failure

Using borax to treat fleas in kittens is the last thing you’d want as it can lead to development issues. The chemical can inhibit their growth rate and prevent their body from reaching full size. Your cat might also suffer from mobility issues in the future if you have used borax regularly since kittenhood.

5. Poisoning

In the worst-case scenario, over-consumption of borax will lead to the death of your cat. Fortunately, this is not very common as cats are rarely exposed to such high dosages of borax in one go. If you do suspect your cat ate a lot of the chemical, getting them to a vet right away can increase their chances of survival.

Look for the following symptoms to identify borax poisoning in your cat:

  • Diarrhea
  • Stomach ache
  • Excessive thirst
  • Respiratory difficulties
  • Scratch marks on skin
  • Altered conscious/mental state

How to avoid borax poisoning?

The easiest way to prevent poisoning is to remove borax from your house entirely. However, if you do want to avail its benefits, keep it in a sealed container away from your cat’s reach.

You should also secure household products that contain borax as an ingredient. Toilet bowl cleaner, laundry detergent, glass cleaner, and even kid’s slime fall under this list. Put all such products away in a closed cabinet or a shelf that your cat cannot climb.

It’s also possible for your cat to lick borax cleaners off the floor or tiles. So whenever you use such solutions, remember to rinse them off thoroughly to remove any residual borax. If you’re using laundry boosters, give the machine a couple of cycles with plain water.


What other household chemicals are toxic to cats?

Many chemicals that we use daily are toxic to cats. Some of these include:

  • Anti-freeze
  • Bleach
  • Insecticides/Pesticidies
  • Detergents
  • Fertilizers

You should also keep certain foods away from your cat as they are highly toxic for felines. The list includes garlic, onion, chocolate, caffeine, sodas, grapes, and raisins, among others. Human medications like anti-depressants, vitamins, and supplements can also cause an overdose in cats.

What would happen if your cat ate borax?

It depends on how much borax your cat has ingested. Small doses are usually harmless and may cause mild stomach upset at best. A mild dose can cause a slight respiratory depression or skin inflammation. But a one-time high dose could result in poisoning. 

How to treat a cat for borax poisoning?

To treat borax poisoning, immediately contact your vet and rush them to the nearest clinic. If your cat is experiencing severe symptoms, your vet might ask you to induce vomiting. At the clinic, your vet will give IV access to dilute the borax and prevent renal failure. 

Is baking soda dangerous for cats?

Yes, baking soda is toxic to cats in large quantities. Just under 2 tablespoons of pure baking soda can lead to toxicity in most cats. It will produce the same symptoms as borax poisoning, such as diarrhea, tremors, seizures, disorientation, and shortness of breath.

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