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My kitten is sick after deworming. Is it worms or another illness?

Updated On September 23rd, 2025

Pet's info: Cat | American Shorthair | Male | unneutered | 2 months and 6 days old

My 8 week kitten just had his first deworming 3 days ago but now he appears very sick. How can I tell if he has intestinal worms or something else?

2 Answers

Most Helpful Answer

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Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on September 7th, 2016

Poor Frodo! Some cats do vomit during deworming due to the strength of the medication combined with the parasites moving through the GI system. These side effects should only last a few days, so if it's been longer than that, I would be concerned that it could be due to something else, such as a GI illness, a foreign body, or pancreatitis. I recommend withholding food for 12 hours, then feeding a bland diet of boiled white meat chicken (no bones) in small amounts several times a day for a couple of days. Then slowly add back in his normal diet. If the vomiting continues in the absence of food, he vomits the bland diet, develops diarrhea, stops drinking water, starts vomiting water, or becomes very lethargic, he will need to see a vet right away.

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Other Answers

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    Answered By Dr. Melanie, BVSc MS

    Veterinarian

    Published on February 19th, 2019

    Yes, this can be caused by the medication and subsequent killing of the worms. Keep an eye on this kitten, and if it becomes lethargic, anorexic, continues to vomit, or keeps having diarrhea, take it into a vet right away.

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    1Pet Parents found this answer helpful

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