Does Plaster of Paris Really Kill Rats?

Plaster of Paris in fine white powder can be mixed with almost anything to kill rats. This is because it may look like corn flour or white sugar, and rats cannot tell the difference as long as you mix it with something they like.

Plaster of Paris kills rats because it contains calcium sulfate that turns into an indigestible solid in the stomach when mixed with fluids. This causes them to bloat and die. To kill rats, mix 1 tablespoon of peanut butter powder with 1 tablespoon of plaster of Paris and let them eat it.

Rats cannot resist peanut batter, which will attract them, while the plaster of Paris will turn into a hard solid they cannot digest after eating. This can also solidify the digestive tract and cause a deadly blockage.

Does Plaster of Paris Really Kill Rats

How to make rat poison with plaster of Paris

Advice: Plaster of Paris will turn into a solid when mixed with any fluid, and the rats will not be able to eat it. Therefore, before mixing it with anything, ensure it is dry and no fluids or water are involved.

You have several options as long as they blend well with the plaster of Paris powder. The idea here is to use any food that attracts rats the most as bait to lure them. Here are five simple ways to make plaster of Paris rat poison at home:

1. Minced meat  + plaster of Paris

Rats love meat, and the best bait to use here is mincemeat steamed and dried. This will blend well with the plaster of Paris powder. The best option is to use dried minced meat as bait.

  1. Pour 1/4 cup of plaster of Paris powder into a clean, dry container
  2. Add 1/2 cup of dried minced meat
  3. Place it near the rat’s hideout and let them eat it

2. Oatmeal + plaster of Paris

You can mix any type of oatmeal, including coarse, pinhead, or Irish oatmeal. All this will work as bait to kill rats when mixed with the plaster of Paris because rats love them. However, ensure they are dried and in powdered foam.

  1. Mix 3/4  glass of oatmeal with 1glass of plaster of Paris powder
  2. Ensure this is properly blended together and place the mixture where you know the rats will find it

3. Flour +  sugar + plaster of Paris

Rats can eat plain flour, but mixing it with sugar will make it more attractive. This will make them eat it in large quantities if mixed with the plaster of Paris. Here is how to do it:

  1. Pour 1/4 glass of flour into a dry container
  2. Add 1/2 glass plaster of Paris
  3. Then mix this with 1/4 glass of sugar
  4. Spread this where you always see the rats

4. Powdered chocolate +  plaster of Paris

One of the best ways to get rid of rats using plaster of Paris poison is to mix it with chocolate powder. Rats can smell Chocolate from a distance, and they will not resist it at all.

  1. Put five tablespoons of powdered chocolate in a clean bowl
  2. Add 8 tablespoons of plaster of Paris to it and mix it well
  3. Let the rats eat the mixture and wait for the results

5. Powdered ground nuts + plaster of Paris

Powdered ground nuts have a strong smell that rats love. Rats love ground nuts because they have a sweet natural taste, and they will eat them even if they are full. Here is how to make rat poison at home with plaster of Paris and powdered nuts:

  1. Simply mix 1/2 cup plaster of Paris powder with 1/2 cup of powdered ground nuts and ensure they blend well.
  2. Place it in a strategic position where the rats will enjoy it.

Use powdered nuts because it is pleasing and easy to mix with plaster of Paris powder to make a fine blend. Using ground nuts in their original form will not be effective because they will not mix well with the powder. Alternatively, you can use powdered sweet potatoes for rats. This will also have the same deadly effects.

How long does plaster of Paris take to kill rats?

It takes 2-4 hours for plaster of Paris to kill rats. This is because the longest time rats can digest food is 2 hours. So if rats eat the bait in large quantities, it will start affecting them after hours.

After the bait starts to solidify in the rats’ stomachs, you will see them stretching with abdominal pains. Since rats cannot vomit, they will become frustrated with an urge to take more water.

Taking water will even make it worse for them because the plaster of Paris will become more sticky. Since they cannot pass it out as a stool or vomit it, they will die in large numbers as long as they take the bait.

This is why powdered chocolate and peanut butter mixed with plaster of Paris is the best homemade rat poison. Once ingested, they become thirsty with stomach upsets after eating the mixture.

Is it safe to use plaster of Paris to kill rats at home?

Using plaster of Paris rat poison at home is safe as long as you do not let your kids or pets reach it. It is important to watch where you place the bait because it may also be tasty to your pets.

Therefore, it is advisable to use this bait at night when everyone is asleep. Remove it very early in the morning before they wake up. This is just an additional precaution to ensure that there are no accidents whatsoever.

It is also important to place the bait in very strategic positions where you know the rats will not miss it. Once you have identified what rats eat in your house, you can trace their activities by finding their stools or the dirt they leave behind after eating in those areas.

When using plaster of Paris poison to kill rats outdoors, ensure you place the bait in hidden positions away from any poultry or pets because it can affect them just like it can affect the rats.

In most cases, rats will leave without food at home. They cannot live without eating. It is important to use baits, i.e., ammonia rat bait, since those rodents will not resist food. For best results, starve the rats before placing the baits so that they can eat them in large quantities.


  1. Oxford Reference: Plaster of Paris composition: Oxford University Press
  2. SFGATE: Can you reuse unused plaster of Paris