Does Boric Acid Kill Rats [Detailed Guide]

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If you have a rat problem at home, you may consider using poison or pesticides. Although using rat poisons to deter rats is viable, picking one might be challenging. Don’t worry! Boric acid can solve your problem, but the question is: does boric acid kill rats?

Yes, boric acid can kill rats, but only if they consume a significant amount. Remember that rats will not even deter by a small amount of boric acid. For rats to ingest it, you must mix a large amount of boric acid with rat bait.

Do you want to know more about rat poisons, including whether or not you can kill rats with boric acid? Learn more by reading the below details.

What Is Boric Acid?

According to National Pesticide Information Center, boric acid is a common naturally occurring pesticide. It is usually available as crystal and powder and is a monobasic acid of boron. Moreover, it contains sodium salts that combine with boron in various ways to maintain its toxicity.

You can find boric acid by different names, some of them are here:

  • Orthoboric Acid
  • Borate
  • Boracic Acid

Above all, boric acid is also present in various products; borax is the most common example. Boric acid is unquestionably among the most adaptable chemicals.

You can use it to manage pests like rats, cockroaches, and termites in your fields. Thus, it is a versatile substance with applications ranging from healthcare to pest management.

Uses of Boric Acid

As already mentioned, boric acid is a versatile item. You can use it as a pesticide, insecticide, and antiseptic agent. Although it is commonly used to control insects like cockroaches in agriculture fields, you can use it in your homes to kill ants.

There are two main mechanisms by which boric acid repels some insects. It initially affects an insect’s neurological system. After that, it drains and damages their exoskeleton. The best approach to applying boric acid is to sprinkle it directly on objects and pests. 

Furthermore, the Encyclopedia of Toxicology claims that boric acid can also be used to protect wood against fire. Boric acid can also dry out plants and prevent the growth of mold and other fungi. In addition, you can use it to make glass, hats, carpets, soaps, and cosmetics.

What Does Boric Acid Do to Rats?

A rat may die if it consumes a large amount of boric acid, but doing so is challenging. However, due to less toxicity of boric acid, it is ineffective at killing rats. More than 5 grams of boric acid causes severe stomach problems and diarrhea in rats, which makes them agitated.

To get the job done, mix ten grams of boric acid with the rat’s favorite food and let it eats. After eating it, rats become restless and die within 5-8 hours. Beware that, in addition to animals, you are not exempt from the toxic effects of boric acid. So, if you have children and pets, avoid using boric acid.

How Much Boric Acid Will Kill a Rat?

Rats cannot harm by less than 5 grams of boric acid. However, depending on the size and environment of the rats, 3-5 grams of boric acid is sufficient to kill the young, whereas 5-10 grams is poisonous to adult rats.

If a rat eats more than 10 grams of boric acid, it results in severe stomach pain and diarrhea within 2-3 hours of consumption. They become unable to move due to extreme weakness. When boric acid intake exceeds 20 grams, rats experience severe tremors and seizures before passing away.

Boric acid consists of boron which causes mild stomach pain in rats. If rats take less than 2 grams of boric acid, it will not kill rats, especially if they drink water. Thus, it is the amount of boric acid that determines whether rats die or not.

How to Make Rat Poison with Boric Acid?

You can use boric acid to kill rats by mixing its large amount with rats’ favorite food like meat, peanut butter, and cheese. Boric acid has no taste or smell, so rats cannot recognize it. You can make a DIY rat poison with boric acid by following the below steps:

  • In a 2:1 ratio, combine boric acid and chopped meat. Then place it along the way of rats. After eating it in large quantities, they will die in 4 hours.
  • Make a solution of boric acid and water and place it near the hiding place of the rats. Swallowing it results in severe toxicity in rats.
  • You can also kill rats by making boric acid from borax. Add some powdered borax to the cheese and let the rats eat it.
  • Additionally, by mixing 1 cup of boric acid with a bowl of diced chicken, you can also manufacture rat poison. Blend it thoroughly to achieve a thick texture. Its smell lures rats and they will die after eating it.

Boric Acid VS Borax

Boric acid and borax are two different forms of the same compound. Borax is extracted directly from the ground, while boric acid is a refined form of Boron. Due to this reason, boric acid is more effective in killing insects than borax.

In addition to being more toxic than borax, boric acid also comes in a finer-grained powder, and rats can easily consume them. Rats who consume large doses of boric acid get severe diarrhea, while rats who consume large amounts of borax become dehydrated.

Although borax is not the best solution for controlling pests, boric acid is a powerful insecticide. Borax is less toxic than boric acid to humans and other animals but consuming them causes skin allergies.

Myths About Boric Acid & Borax

It is a widespread myth that you can kill rats and mice with boric acid and borax. The truth is that they are not strong enough to kill pests like rats. They can only kill insects like roaches and flies. However, if rats and mice eat boric acid or borax in large amounts, they will die.

According to the Brazilian Journal of Otorhinolaryngol, boric acid causes middle ear infections in rats, but it is not fatal for them. Similarly, boric acid affects the reproductive system of pregnant mice but does not kill it. 

Although everyone is familiar with killing rats with boric acid, your misunderstandings have now cleared. You must ponder the following points:

  • You cannot kill pests like rats, snakes, and mice with boric acid and borax.
  • Only insects will die after consuming boric acid and borax.

How to Kill Rats Instantly with Other Ingredients?

As boric acid is not strong enough to kill rats, you may consider other poisons to get rid of rats. A variety of rodenticides are available to kill rats. Some of them are listed below:


Cholecalciferol (Vitamin D3) is an effective rodent bait. It increases the calcium level in blood plasma by mobilizing it from the bone matrix. This increased amount of calcium results in kidney failure and heart damage in rats. Although vitamin D3 significantly lowers the danger of subsequent poisoning, it kills rats and mice in 3 days.

Zinc Phosphide

Zinc phosphide is common in land and aquatic regions to control pests and rodents. You can use it to prepare oat and wheat bait to kill rats. It reacts with the stomach acids of rats and releases phosphine gas. Phosphine gas spreads rapidly throughout the body of rats and reduces the amount of oxygen. As a result, rats pass away. 

Strychnine Sulfate

According to the Handbook of Toxicology of Chemical Warfare Agents, Strychnine sulfate is a naturally occurring poison to kill rats and wild animals. It causes restlessness, kidney failure, and severe tremors that eventually lead to the death of rats. Because of its high toxicity, many countries do not recommend using it against rodents.

Barium Carbonate

Barium carbonate is also a common rodenticide for killing rats. It increases the amount of potassium in rats’ bodies, and they become feeble. As a result, they die due to its toxic effects.

Symptoms of Rat Toxin Poisoning in Humans

Although the above poisons are the best rodenticides, they may be fatal for you and your kids. As things worsen, you become aware of the poisoning that is slowly taking place in your body. So, you should wear gloves and a mask while applying poisons to rats.

Moreover, you must know the following symptoms for immediate treatment of poisoning in your body.

Symptoms Caused by Boric Acid and Borax Toxicity

  1. Boric acid causes nausea, vomiting, diarrhea, and skin irritation.
  2. Borax is more toxic than boric acid and causes eye damage, fever, cough, and shortness of breath.

Symptoms Caused by Colicalciferol Toxicity

  1. Reduction in appetite
  2. Nausea, vomiting, and fatigue
  3. Increase urination
  4. Bone and kidney problems

Symptoms Caused by Zinc Phosphide Toxicity

  1. Headache
  2. Dizziness
  3. Nausea, vomiting, and lethargy.
  4. Shortness of breath
  5. Cough and chest pain
  6. Excessive thirst

Symptoms Caused by Strychnine Sulfate Toxicity

  1. Respiratory failure
  2. Brain damage
  3. Seizures
  4. Muscle spasm

Symptoms Caused by Barium Carbonate Toxicity

  1. Nausea and vomiting
  2. Watery diarrhea
  3. Pain in stomach
  4. Cardiac issues

Wrapping Up

It can be frustrating to deal with a rat infestation in your home and garden, especially if it gets out of control. There are many home remedies to get rid of rats but choosing one is a real headache. Boric acid is a common household rat poison, but it is not effective enough to kill rats.

Although boric acid won’t kill rats, the aforementioned preventative measures and home treatments will certainly keep them at bay. Above all, if there is an outbreak of rats, make a quick call to the pest control experts.

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Salihoglu M, Dogru S, Cesmeci E, Caliskan H, Kurt O, Kuçukodaci Z, Gungor A. Ototoxicity of boric acid powder in a rat animal model. Braz J Otorhinolaryngol. 2018 May-Jun;84(3):332-337.

National Pesticide Information Center