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Is lethargy a normal reaction for my kitten after second shots?

Updated on September 23rd, 2025

Pet's info: Cat | Domestic Shorthair | Male | 3 months and 16 days old | 3.29 lbs

My kitten had his second round of shots yesterday. He was fine when we got home (4pm). This morning he has been pretty lethargic is it normal. He had no fever yesterday when the vet took his temperature so I am assuming he does not today.

2 Answers

Most Helpful Answer

Answered By Dr. Elizabeth

Veterinarian

Published on July 9th, 2020

Hello and thank you for your question. I hate to hear that Covid-Max (love that name!) is not feeling well.

It's possible that Max is having a vaccine reaction. These generally occur within 24 hours and can range from severe lethargy, fever, swelling of the face to collapse. He may have a fever today which is not uncommon with a vaccine reaction (though not always present).

I recommend to call your veterinarian right. They may want to exam Max again to check for signs of a reaction and to treat him. Additionally, if this is a vaccine reaction, they will take precautions in the future to decrease the potential for another reaction. This may include giving him an anti-histamine before his vaccines, spreading out his vaccines or giving him a steroid.

I hope this helps and that Max starts feeling better quickly! Please feel free to post any additional questions.

1Pet Parents found this answer helpful

Related Answers from Veterinarians

Answered By Tomasz Wnuk
Veterinarian
Hello and thank you for contacting Petco Pet Education Center, formerly Petcoach. Fever and lethargy are the most common side effect of vaccination in cats. It happens particularly often after vaccination against leukemia virus. Your kitten should be back to normal within 24hrs, if he is not please take him back to your vets for an appointment.
1Pet Parents found this answer helpful

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