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What are cephalexin side effects for dogs, including drowsiness?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed Small (up to 22lb) | Male | unneutered | 3 years and 2 months old | 15 lbs

What are the side effect of cephalexin? Does it cause drowsiness?

1 Answer

Most Helpful Answer

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Answered By Mariya Gugel, DVM

Veterinarian

Published on December 14th, 2017

Thank you for using Petco Pet Education Center, formerly Petcoach! Cephalexin is a commonly used antibiotic and has minimal side effects. Most of the side effects have to do with intestinal signs - mild nausea, diarrhea, or decreased appetite - all of these can be causing Chicharito to be a little bit less active. In rare cases, cephalexin can cause kidney damage, but this is in dogs who already have kidney disease. I hope this helps and am happy to answer any other questions you may have regarding your pets medications!

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