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Why is my kitten vomiting yellow and not eating after dewormer?

Updated On September 23rd, 2025

Pet's info: Cat | Domestic Shorthair | Male | neutered | 2 months and 5 days old | 5.73202 lbs

Hi I took my kitten for the 2nd time to the vet this week and he still won't eat or drink, Dr did not find any infection so what do I do now? His been like this for two days and he vomited twice yellow liquid. The vet just keeps giving him medicine that helps with vomiting, he suspects the revolution dewormer was too strong. ... please help

4 Answers

Most Helpful Answer

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Answered By Ana M, DVM

Veterinarian

Published on November 19th, 2018

Thank you for submitting your question regarding your kitten. If he is not improving, then I recommend that he has a further work up. He should have fecal testing, blood work and x-rays of his abdomen to determine the cause of his vomiting and inappetance. Kittens can react to deworming medication, but it is typically a short lived reaction. It worries me that he is still ill. There is likely another another disease process present. In the meantime, encourage him to drink so that he does not become dehydrated. I hope this information helps!

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    Answered By Vanessa Yeager DVM MPH

    Veterinarian

    Published on April 7th, 2020

    Hi and thanks for posting. I would be sure to recheck a fecal test with your veterinarian. Certain parasites and intestinal worms take several round of dewormer to completely get rid of. A follow up fecal test will be able to determine whether or not Larry has cleared the infection. I hope this helps!

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    Answered By Dr. Melanie, BVSc MS

    Veterinarian

    Published on January 8th, 2017

    You are correct that the vomiting could be due to the worms, but deworming treatments can also cause vomiting as a side effect. It's serious that he isn't eating or drinking. When a cat stop eating and drinking, it is time to see the vet as Lucky could get dehydrated quickly. I would have Lucky seen by a vet now who can treat his symptoms.

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    Answered By Dr. Melanie, BVSc MS

    Veterinarian

    Published on February 25th, 2019

    It could be from the dead worms moving through Stich's GI tract, but it could have another cause such as a GI illness. Whenever a dog is both vomiting and having diarrhea, it's time to see a vet. I'd take him into one first thing in the morning. I hope this helps.

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