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How long until Benadryl completely helps my dog's seasonal allergies?

Updated On September 23rd, 2025

Pet's info: Dog | German Shepherd | Male | 1 year and 1 month old | 64 lbs

Hi there, my dog is a 1 year old german shepherd. He has a sensitive stomach we have had to change his food a few times. It finally seems to be one he can eat. He also started with some seasonal allergies. Runny nose and coughing. The vet has him on Metoclopramide to get his stomach straight and had me start him on benadryl for allergies yesterday. He still threw up a little last night but, not nearly as bad as what it has been. I am just curious does it take benadryl more than a day to help 100

1 Answer

Most Helpful Answer

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Answered By Dr. Elizabeth

Veterinarian

Published on April 22nd, 2020

Benedryl should work within 24 hours but remember that every pet is different and while some may do really well on benedryl, some will not. Give it a few days and if it doesn't seem to be helping, call the vet and ask about the next medication to try. GSD are pretty sensitive as a breed. I'm not sure what Crow is currently eating but I feed most of my GSD Royal Canin German Shepherd and most of them do very well on this diet. I hope this helps.

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