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Why is my cat having diarrhea after dewormer and booster shots?

Updated on September 23rd, 2025

Pet's info: Cat | Domestic Shorthair | Female | spayed | 4 months and 10 days old | 5 lbs

My cat had a vet appointment on Saturday and everything was fine she got 2 shots ( dewormer and the 1 year booster) all of a sudden today she had diarrhea, I’ve only noticed once so far today, there’s been no food changes or anything different from her routine , but at what point should I be concern?

1 Answer

Most Helpful Answer

Dr. Melanie, BVSc MS

Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on February 11th, 2019

Deworming treatments as well as vaccines can cause diarrhea as a side effect. I wouldn't be concerned about Rae just yet, and I can give you a home remedy to see if that helps. Withhold food for 6 hours, then feed 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 her normal diet. If the diarrhea continues on the bland diet, she starts vomiting food, stops drinking water, starts vomiting water, or becomes very lethargic, she will need to see a vet right away. I hope this helps!
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