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Home > Cats > How Long Will My Cat Have Diarrhea After Deworming? Vet Reviewed Facts

How Long Will My Cat Have Diarrhea After Deworming? Vet Reviewed Facts

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Dr. Lauren Demos

Veterinarian, DVM

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It’s not uncommon for cats to experience an infestation of intestinal parasites. Fortunately, you can get your cat dewormed to help treat parasitic infestations, but your cat may experience some side effects throughout the process, which include diarrhea.

Diarrhea can be triggered by gastrointestinal upset caused by the parasites or by deworming medication. If deworming does cause diarrhea for a few days, it is generally not a reason to be too alarmed.


What Is Cat Deworming?

Gastrointestinal parasites are easily transmitted and often contagious between pets in the same household. Some of the more common parasites for cats include roundworms, hookworms, tapeworms, and whipworms. They can be transmitted through  fleas, mosquitoes, and other insects and smaller animals. Parasites can also be transmitted through feces, and nursing mother cats can transmit them to their kittens through their milk.

It’s common practice for kittens to get dewormed and for adult cats to either take preventative medication or get dewormed every few months.1 The type of deworming will depend on your cat’s lifestyle. Veterinarians can prescribe oral or topical medications.

The process of deworming will also depend on your cat’s condition. Mild cases can be resolved fairly quickly, while more severe cases may require multiple doses of medication over the span of weeks.

vet giving liquid dewormer to a cat
Image By: MDV Edwards, Shutterstock


Treating Cats Experiencing Diarrhea During Deworming

Diarrhea can be a side effect of some deworming medications. So, make sure to ask your veterinarian for common side effects for whichever medication your cat ends up taking.

Unlike dogs, there’s really no need to have your cat fast from food while experiencing diarrhea. However, you can change up your cat’s diet to include food that’s easier for it to digest, including gastrointestinal-specific diets. Wet food may also be helpful for cats with diarrhea because the water content can help keep them hydrated. Some cats can also benefit from taking probiotic supplements to help maintain a healthy bacterial population in their digestive tracts.

If your cat continues to have diarrhea after a couple of days, contact your veterinarian for more follow-up care information. Your veterinarian can help monitor your cat’s condition and prescribe anti-diarrheal medication, if necessary.

sick cat covered in blanket lies on the window in winter
Image By: Germanova Antonina, Shutterstock



Diarrhea is a side effect that some cats may experience while taking deworming medication. The issue can go away on its own after a couple of days. In most cases, cats won’t need to fast food, and they can benefit from eating easily digestible foods and taking probiotic supplements.

However, if diarrhea persists for more than 2-3 days, or you have other concerns, or your cat already has underlying medical conditions, consult your veterinarian for more care instructions. Cat deworming can take a while, so it’s best to be in consistent communication with your veterinarian. This will help your cat recover completely as quickly and efficiently as possible.

Featured Image Credit: Mila Naumova, Shutterstock

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