How Does Rat Poison Work?

Rats can be pesky little creatures. These rodents can survive in different environments but may choose to become unwanted tenants in your household.

Rats are not only ugly, but they also tend to reproduce really fast.

The other problem with rat infestations is that they carry pathogens like the Hantavirus, which affects humans. Some rat-caused diseases are airborne, and you don’t need contact with the actual rat to contract them.

The diseases aren’t the only thing that makes rats a menace. These creatures can cause damage to your home as they chew through anything: clothes, plastic coatings on electrical wires and plastic pipes.

They can even do a number on your food supplies. Once they get to your food storage, rats will leave crumbs in hard-to-reach places, which will attract insects and other pests.

When you see a rat, the first thing that comes to mind is how many more of those creatures are around, and where do they live? Where are they coming from? And how much damage have they done?

When getting rid of rats, people think of poison because they’re considered the most effective. But how does rat poison work?

We have done our research on everything rats, how rat poison works and alternative mechanisms.

Rats can travel miles for food and water

Where do rats live?

Rats can live anywhere as long as they have access to food, water and nest-building materials.

They prefer somewhere warm and can travel for miles to look for food and water, which may make it hard to gauge how big an infestation you have.

They live in packs that are mostly male-dominated and can breed fast. One female rat can give birth to almost 15 babies at a time.

In your house, they can find refuge in attic walls, chimneys, the kitchen, laundry area and basements.

Outside your home, look for signs of rats in sheds, garages, compost bins and around trees and shrubs.

To gain access to your house, rats are known to gnaw through brick walls, cardboard boxes, insulation materials and wooden joints to make access points. They are very sly and can fit into really small spaces, almost half their size.

Because of their nocturnal nature, it may take a while to realise that there’s an infestation.

You may hear them run around between dusk and dawn, and if you leave food out, you may notice gnaw marks in something noticeable such as groceries.

Seeing rats during the day is a sure-fire sign that the rats have established a stronghold in your household.

How does rat poison work?

Rat poison consists of mixed, lethal compounds that are used to get rid of rat infestations. These chemicals either come as pellets, powders, pests, treated grains or seeds.

In the past, rat poison used to have heavy metals such as arsenic. There are several types of rat poison, each of which elicits different effects on its victims. You can classify rodents as either non-anticoagulants or anticoagulants.


Anticoagulants are laced with Vitamin K, which prevents blood from clotting.

These drugs may cause a slow and painful death through internal bleeding.

It used to be the case that rats could take days to die from ingesting anticoagulants, but manufacturers have developed more potent drugs that can kill within hours of ingestion.

Popular anticoagulants may contain active ingredients such as bromadiolone, warfarin, brodifacoum and difethialone.


In rats, non-anticoagulants mostly contain bromethalin, zinc phosphide, thallium and cholecalciferol.

Bromethalin works within three days and works by causing the cells in the nervous system to cease energy production.


Cholecalciferol works by raising the calcium level in a rat’s body from the food it ingests, which then messes with how its body functions.

Some rats are resistant to anticoagulants, and cholecalciferol is the remedy for this.

Cholecalciferol is single-use and will cause a calcium build-up in a rat’s blood vessels, kidney, stomach and lungs which then causes heart problems, uncontrollable bleeding and possible kidney failure.

It’s still effective even if the rat takes a small dosage frequently.

Female rats can give birth to up to 15 babies at once


Some rat poison brands use thallium as their active ingredient. Although this was popular in the 1920s, it’s nowadays uncommon.

The chemical is tasteless and has no smell, which makes it harder for rats to realise.

This chemical is well-known for depleting the production of energy when ingested. A fun fact is that thallium can enter the bloodstream through intact skin and that the rodent can be exposed to it through inhalation.


Bromethalin works by messing up the cells in the central and peripheral nervous systems.

Manifestations of this drug in rats include seizures, vomiting, losing limbic control, eventual coma and eventual death.

Metal Phosphides

Using metal phosphides such as zinc phosphide, magnesium phosphide and calcium phosphide is another effective way of killing rats.

These drugs aren’t that popular on the market, though. These chemicals are considered very lethal and may also infect other animals.

Zinc Phosphide is single-use and is mostly hidden in food as bait. When ingested by a rat, the acid in its digestive system mixes with the phosphide to release toxic phosphine gas. The rat’s death will occur somewhere within three days.

Metal phosphides smell like really concentrated garlic and usually come in the form of tablets or pellets. While rats are attracted to this smell, it repulses other animals.


Sometimes, rat poison companies mix calciferols with anticoagulants, which makes a more potent rodenticide.

The combination packs a double punch by causing both hypercalcemia and hemorrhage in rats. This also significantly reduces the time it takes to kill the rats.  

Other classifications

You can also classify rat poison depending on its effects on other animals and humans.

Toxic rodenticides can not only affect the rats you’re trying to get rid of but also you and other animals you’re rearing.

The instructions manual packaged with the poison you decide to use will clearly explain the same.

Some of these poisons aren’t toxic, but this doesn’t mean you handle them without due care. They may still cause effects such as flushing or low blood pressure. Essentially, you should manage all poisons with proper care.

Rat poisons can also be either slow or fast-acting.

Fast-acting poisons will have the rats manifest the symptoms faster than slow ones, making them ideal for a larger infestation.

The problem is that rats are quite brainy creatures, and they can learn to avoid these poisons once they notice other rats getting sick.

Slow-acting poisons don’t kill fast, but many rats can be affected without noticing it, making it more effective because their manifestations take long.

Some rat poison can come in brightly coloured form, so make sure you keep well away from children

Is rat poison effective?

Rat poison effectively deals with rat infestations, especially because you can place the poison anywhere within reach for easy access.

These poisons can kill multiple rats within a few days, especially when placed in rat-prone areas.

Using rat poison to kill a rat should be your last-ditch effort because of how lethal the drug is.

Children and pets will be affected when they encounter the poison, especially if they ingest the drug.

Some of these chemicals are so potent that if a predator eats the rodent, then they may get poisoned.

Countries are banning some of these poisons because of their effectiveness and effect on humans and other animals.

How to gauge the success of rat poisoning

Rats take a few days to die after ingesting the poison, and therefore you will notice a decrease in their number within the first five days.

You can make this fast by actually investigating where they frequent the most and placing your poison there so that they actually ingest it.

You may start noticing a change in the colour of rat droppings, probably red or blue, from the colouring agents that rat poison manufacturers add to rat poison. You will also start seeing dead rats or a reduction of fresh rat droppings as the rats die.

The rat poison may not kill all the rats, but when rats notice that they’re dying in large numbers, the remaining ones will migrate to other areas.

How much rat poison should you leave out?

The amount of rat poison you need to leave out depends on the amount rats need to eat before the desired outcome.

It also depends on the extent of rat infestation and whether the poison is fast or slow-acting. 

You don’t need to leave much of a fast-acting poison because most of these are single-use. In the case of slow-acting rat poison, leave as much as you can so that the rats can eat them repeatedly as the toxins build up.

You can check out the poison’s packaging instructions manual to gauge how much you should use.

How safe is rat poison?

Although effective, rat poison can have adverse effects if ingested or contact humans and other animals.

These poisons come in bright colours, which attracts children to play with them. They also taste sweet to encourage rats to continue eating them, and unfortunately, kids love sweets too. This is why we recommend rat poisoning as a method of last resort.

Fast-acting rat poison, for example, leave lethal amounts of toxins in them even after they die and will affect any other animals that eat them.

As discussed, some of these poisons can take a long time to manifest, and rats tend to travel everywhere.

If you live somewhere with cats and dogs, or other big predators, then some of these rats may kill them too.

Rat poison would be extremely harmful to household pets such as cats

Safety practices when using rat poison

There are common safety practices, such as using gloves when handling dangerous chemicals, including rat poison.

You should also wash your hands directly after getting in contact with the toxins. Some of these poisons can also affect you when you inhale them, so use a protective covering on your nose and mouth. It may not be that bad, but prevention is better than cure.

Keep your rodenticides away from children and pets. Most of these chemicals are attractive to animals, and your pet or child may be tempted to investigate their content so it’s recommended you use an airtight container to store rat poison.

Rats may be attracted to other foodstuff and leave your poison-laced bait alone. The best way is to remove any other food choices to eat what you’ve provided them with.

Keep any livestock feed, food storage, water and other edible liquids sealed to see fast results. This will also prevent cross-contamination.

Alternatives to rat poison       

Symptoms of rat poisoning portray how inhumane it is to kill rodents this way. You should use this method when all other rat control methods don’t work.

Other safer rodent prevention and control mechanisms include:

Rat Proofing

Rat proofing is more of a preventive mechanism and involves making your household an unwanted location for rats.

This method mainly involves enhanced cleanliness because rats don’t thrive in clean places.  Start by covering any leftovers and putting your foodstuff in closed glass and metal containers. 

Leave no clutter because that’s where they hide. Keep your garden free from bushes and keep your house tidy.

The next thing would be to be careful where you live pet food. You should store bird and pet food somewhere enclosed to prevent rats from getting into it. Do the same for livestock feed.

Rats can fit into really tight spaces, so check your sewers, drainage systems and pipework frequently for any damage. These creatures can take a small opportunity, such as an open hole, and gnaw on it until they find an entryway.

You can also prevent rat infestations by managing your waste disposal. Ensure your dustbin is sealed, and always replace any broken bins which eliminate their food source. Always line any foodstuff with compostable liners.


There are several forms of trapping mechanisms you can use.

These include using a glue board, stretched rubber ring, gas traps, spring-powered killing traps, electrocution devices and live capture that you can use to manage rat infestations.

These methods may be slower, but they’re more humane and effective – we’ve put together a guide to the best rat traps here.

Trapping looks brutal but can be a more humane way of dealing with rats

Use professional pest control

Some companies offer professional pest control, which mostly involves an integrated pest management mechanism.

These companies monitor the extent of the infestation and damage and choose the best way to deal with the problem.


Preventing a rat infestation is way easier than managing one. Keeping your house and compound clean should be your first choice in preventing rats from finding your home habitable.

Rat poisons are dangerous because they affect your target victims and unintended bystanders such as other mammals, so where you can use other effective practices, do so.

Always look out for yourself and your family by storing any poisons as far from human and animal reach possible.