Pyrantel for Cats: Dosage, Uses, Side Effects (Vet Answer)

Pyrantel pamoate is an anthelmintic (dewormer) drug that is frequently used in cats, dogs, small animals, and birds. Its use is “off-label” in cats but many vets safely prescribe it as an effective treatment. Pyrantel can be used on its own or in combination with other anti-parasite drugs for the treatment of heartworm and intestinal parasites.

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What Is Pyrantel?

Pyrantel pamoate is a popular anthelmintic deworming drug. It is commonly used in cats to combat hookworms, intestinal roundworms, and stomach worms. Pyrantel is also used in other species such as rabbits and birds “off label.”

Pyrantel acts as a depolarizing neuromuscular blocking agent. It works by causing sudden contraction followed by paralysis of the worms. This means they cannot latch onto the lining of the cat’s intestines, so they are removed from the body as the contents of the guts are moved down the gastrointestinal tract. Pyrantel is not well absorbed by the cat’s intestines, so the cat is unaffected by the drug. The worms are usually passed out along with the feces.

Occasionally vomiting and diarrhea can be seen. Your cat may stretch out their abdomen and strain when passing larger worm burdens due to the space it occupies. Pyrantel in cats is used for the treatment and prevention of hookworms and roundworms. It cannot be used to treat tapeworms or whipworms.

Pyrantel pamoate should be stored away from direct sunlight, in a closed container. It should be kept at room temperature—approximately 15°C–30°C or 59°F–86°F. It should always be kept out of reach of children and pets in an appropriate child and pet-proof container.

How Is Pyrantel for Cats Given?

Pyrantel pamoate comes in various forms so you can decide which one is best for your cat. You can use capsules, tablets, chewable tablets, and a liquid suspension. The usual dose for Pyrantel pamoate is 2.5 to 5 mg per pound (which is 5 to 10 mg per kilogram) as a single dose, then a repeated dose in 2 to 4 weeks. Ensure you give the product for the correct length of time as recommended by your vet.

Pyrantel pamoate is dosed by the oral route. It can be given with or without food. If your cat vomits after receiving the drug on an empty stomach, it may be suggested that you give it with food after this. If your cat does vomit, consult your vet for advice.

If you are using the liquid form, ensure you shake well before administering it to your cat. Extra care must be taken when measuring out liquid amounts. Always ensure that you consult your vet before giving any products that contain pyrantel pamoate and always keep to the dosing instructions given by your vet.

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What Happens If You Miss a Dose?

It is not the end of the world if you miss a dose of Pyrantel. You can give the dose when you remember or as soon as you are able to. This is acceptable unless the next dose is due, then you must only dose once and miss a dose. Once you have given the later dose, you must wait the appropriate period as recommended by your vet before dosing again. Do not give two doses at once or give any more doses than what is recommended by your vet.

Pyrantel is normally very well tolerated by cats, but if there are signs of toxicity, or you think you have overdosed them, you may notice signs such as:

  • Breathing difficulties
  • Lethargy
  • Hypersalivation
  • Vomiting
  • Diarrhea
  • Disorientation
  • Weakness
  • Collapse

If you see any of these signs, contact your vet immediately. You can also contact the Pet Poison Helpline or Animal Poison Control Centre.

  • Pet Poison Helpline (855) 764-7661
  • ASPCA Animal Poison Control (888) 426-4435

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Potential Side Effects of Pyrantel

There are very few side effects of Pyrantel pamoate as long as the drug is dosed correctly. However, as with all drugs, there are always some clinical signs seen in some cases. These may include:

  • Vomiting
  • Diarrhea
  • Nausea
  • Loss of appetite

Other side effects that are not directly related to the drug but occur due to the action of the drug can also include intestinal obstruction. This happens if a heavy worm load is present. The obstruction usually occurs due to an impaction of the worms. It is more commonly seen when a smaller cat with a big parasite burden is treated. This is because pyrantel is a spastic paralyzing agent. It causes all of the worms to release their latch on the lining of the intestinal wall and be expelled together. This can cause vomiting, diarrhea, and heavy straining.

The medication usually takes 24 hours to take effect, so these signs should stop then. If they do not, consult your vet for advice. Caution should be taken if using pyrantel in elderly or very weak patients, or any cats with an underlying health disease.

It is safe to use pyrantel in cats that are nursing their young. Consult your vet to discuss the specific safety guidelines for the use of pyrantel in pregnant queens as there are different dosing instructions that need to be followed.

In very rare cases, pyrantel can be toxic if used over a long period. If you are worried your cat may be suffering from an adverse reaction to the product, consult your vet immediately.


Frequently Asked Questions

Which worms does pyrantel pamoate treat in cats?

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Pyrantel pamoate is used mainly for the treatment of a group of worms called ascarids. These include roundworms such as Toxicara cati and hookworms, such as Ancylostoma tubaeforme, Ancylostoma braziliense.

Which worms are not covered when using Pyrantel?

Pyrantel is very effective at treating roundworms, however, it has a limited spectrum for the treatment of other parasites. If you are using pyrantel, you will need to add in something else to cover giardia, toxoplasma, whipworms, tapeworms, and coccidia. Your vet will be able to advise you on different treatments that can be used in combination.

Why do I see worms in my cat’s feces after using Pyrantel?

If you are seeing worms in your cat’s feces after administering pyrantel, this is because the drug is working and the worms that have been attached to the lining of your cat’s intestines are now being expelled from the body. This is a normal response to the treatment if intestinal worms are present in your cat.



Pyrantel is a popular anthelmintic treatment prescribed off-label for use in cats. It is used for the treatment of intestinal roundworms and hookworms. It does not cover many other parasites. Pyrantel is well tolerated in cats and adverse effects are rare unless an overdose is given. If your cat has a very large worm burden, they may suffer from intestinal obstruction if they are trying to pass out a lot of worms at one time.

Your vet will be able to advise you on doses and frequency of use depending on the weight and age of your cat. Pyrantel must not be used without veterinary instruction.

Featured Image Credit: David Herraez Calzada, Shutterstock

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About the Author: Tony Ramos