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What Are the Chemicals in Rat Poison?

Last Updated: 27.11.22


Using even the best rat poison comes with many risks. Rodenticides contain various substances, from anticoagulant agents to hypercalcemic agents, metal phosphides and even Strychnine. Each of these substances acts differently when ingested. Plus, all of them have specific side effects that you should be familiar with before you use them for the first time.


What are these chemicals called?

The technical term for the pesticides used to kill rodents, rats included, is rodenticide. Rodents is an umbrella term is used when talking about animals that have an innate need to gnaw and that have incisor teeth that grow continuously. Among the most popular rodents are squirrels, rats, mice, beavers, chipmunks, and even woodchucks.

There are numerous ingredients that one might find in a product that was designed to be used to kill rodents such as anticoagulants, metal phosphides, hypercalcemia as well as lesser-known alternatives that are generally used to kill specific types of rats.



Rodenticides that were formulated to contain anticoagulants are known for their effectiveness. Anticoagulants work by blocking the vitamin K cycle in the blood system of the pest. As a result, the body will respond by not being able to produce essential blood-clotting factors, most importantly, factors VII and II.

Apart from this metabolic disruption, anticoagulants such as 4-thiochromenone and 4-tydroxycoumarin can also cause direct damage to the blood vessels of the rodents by making their capillaries increasingly more permeable. Consequently, animals suffer from internal bleeding.  

Even though a single dose of a product of this kind can be effective, the results are not instant. This means that the animal will most likely die only after a couple of days since the moment that it ingested the product. Because of how this solution works, it has been deemed cruel by many. Some have also argued that products that contain anticoagulants are inhuman.



Metal phosphides

If you want to invest in a product that can kill the pests that you are dealing with fast, in one to three days, you should purchase a solution that contains metal phosphides. 

The baits that are made using metal phosphides include zinc phosphide, an inorganic chemical compound that, once it reaches the digestive system of the animal, it generates a very toxic gas. 

Exposure to this substance comes with serious side effects such as damage to the liver, heart, brain, and kidneys. The baits that are made using this chemical have a strong smell similar to garlic. 

As a plus, while this odor attracts rodents, it has the opposite effect on other mammals.  However, it should be pointed out that some birds, including turkeys, are not sensitive to its smell and that they might feel curious enough to eat it. This situation should be avoided at all costs given the effects that zinc phosphide has.

Alternatives that contain phosphides are generally used in situations where the vermin are resistant to anticoagulants. Plus, these products are usually cheaper than some of the anticoagulant-based solutions out there. 

Because metal phosphides don’t buildup in the tissue of the animals that consume it, the risk of having to deal with secondary poisoning is low. According to researchers, products that contained phosphides were the most popular rat poisons before the advent of anticoagulants.



As you might already know, hypercalcemia is a medical condition that results from the level of calcium in one’s body being above normal rates. When too much calcium is accumulated in one’s system, the person’s bones become weak. Plus, one might develop other symptoms such as kidney stones and heart and brain issues.

Hypercalcemic agents are also widely used in rodent poisons and they are made up of cholecalciferol and ergocalciferol, two chemicals that affect the phosphate and calcium homeostasis in the body of the animal. 

When used in rat poison, the hypercalcemic agents act by increasing the calcium absorption and then mobilizing the absorbed substance in an ionized form. Therefore, after the rat has ingested a lethal dose of bait, its calcium levels are so high up, that its stomach walls, its blood vessels, lungs, and kidneys are calcified. 




Products that contain Strychnine can also be used as rat control. They were especially widely used before the SWW. Because there were numerous cases where this substance was used to kill people, today, only certified applicators can purchase it.

This substance was brought over to Europe, from India, by boat. Back then, this poison was very popular as most cargo ships were infested with rats.

Strychnine is an alkaloid that comes from a tree called Strychnos nux-vomica that originates from India. Intoxications with Strychnine are very cruel as this chemical substance kills through asphyxiation. 

Once ingested, this drug acts by paralyzing the muscles that a person/animal uses to control breathing. Because this substance kills slowly and painfully, some argue that it should not be used on rats.



Bromethalin is a neurotoxin used in single-dose rodenticides. It was first regulated in 1984 by the Environmental Protection Agency. It works by stopping the cells in the nervous system from producing more energy. As a result, the brain of the animal swells up and it dies in a short period. 

This substance is used when baiting rat burrows and to control severe infestations. However, many argue that it works just as well indoors, provided that you place it in an area where it is not accessible to pets or children.


Sodium fluoroacetate

Also known as sodium monofluoroacetate, this substance is also used in pest control, especially in Australia. This chemical is produced by plants that use it to defend themselves against herbivores. In total, there are over forty plants that create it, around the globe.

The substance was patented as a pesticide in Germany, in 1927 and it was introduced in America in 1946 by pest control operators. Because it was used, at first, as bait water, the product was mixed with a dye. 

Yet, at the end of 1949, at least eight people, including two children were unintentionally poisoned, and 16 people were killed, including four kids. As a response to this situation, stricter regulations were imposed. 

Once the sodium fluoroacetate enters the body, it goes through a couple of changes and as a consequence, it affects the body’s ability to convert food into energy. So, slowly, the body of the animal shuts down. The symptoms start to show half an hour after the ingestion. There is no antidote for this poison.



What are the signs of rodenticide poisoning?

If one of your pets accidentally ingests rat poison, you should know what symptoms to look for. For instance, exposure to anticoagulant rodenticides manifests by difficulty breathing, bleeding profusely, weakness, shaking, seizures and vomiting. Signs in people are internal bleeding, bleeding from the nose, skin or gums. 

Zinc phosphide causes vomiting within the first hour of ingestion. A telltale sign is that the vomit might have a garlic-like smell. Other symptoms in humans are shortness of breath, coughing, convulsions, and delirium. 

Additionally, Bromethalin ingestion is known to cause seizures, muscle tremors, sensitivity to light. Animals that eat this poison might develop these symptoms after 8 to 12 hours. They also lose their ability to control their hind legs. If people consume Bromethalin, they usually display an altered mental status.

If you notice any strange behavior in your pets you must get in touch with your vet for immediate treatment. Also, if any of your family members do not feel well after you have used rat poisoning, you must take them to the hospital. 


How to prevent any unwanted poisonings?

To start, you should keep the area around your house clean, so that rats do not feel attracted to check it out. Besides, you should seal any cracks in the foundations of the home and you should plug all openings so that these pests cannot get in.

The rodenticide that you decide to use should be formulated for home use. To avoid any problems, be sure to read the instructions before you place the bait. 

If you have small children or if you own animals, you should use traps instead of poisoned baits. If you have no or limited experience with dealing with an infestation of this kind, it is strongly recommended that you hire professional exterminators. 



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