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Why is my puppy sick and sleepy after flea and tick medicine?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed Small (up to 22lb) | Male | 6 months and 17 days old | 3 lbs

My puppy is not himself after I gave him flea and tick medication. He is really sleepy and will not eat or drink much help?

2 Answers

Most Helpful Answer

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Answered By Destini R. Holloway, DVM

Veterinarian

Published on March 5th, 2017

He could be having an adverse reaction to the flea/tick medication. Give him a bath immediately! Then contact your local vet to have him examined and treated for an acute allergic reaction. The most important thing though is to wash off the product. Using dawn dish detergent works best to strip the product off. There is a chance that he has absorbed a good bit of the medication already, but this will help prevent further absorption and subsequent illness. Most adverse reactions to flea/tick products do well with time (minimum 12 hrs to see improvement). I hope your puppy Harley recovers soon!

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    Answered By Dr. Melanie, BVSc MS

    Veterinarian

    Published on

    It could be that Harley is experiencing a mild reaction to the flea and tick medication, and I would monitor him for now. If he starts vomiting, having diarrhea, muscle tremors, incoordination, hives, or difficulty breathing, I would take him into a vet immediately. Should Harley still be lethargic in the morning, and not eating or drinking much, I would have him seen by a vet for a health check.

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