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My dog has hives, Benadryl isn't working. What can I do now?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed Large (61lb +) | Male | neutered | 80 lbs

My dog has hives. They just developed yesterday and I'm concerned. He hasn't had a change in diet and there are no chemicals or plants that he could have come in contact with. Benadryl hasn't helped and he is acting very out of the ordinary. He keeps scratching and I can't get to a vet until morning.

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4 Answers

Most Helpful Answer

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Answered By Kevin Sanada, DVM

Veterinarian

Published on October 6th, 2017

Allergies are definitely a possible cause these hives. Allergies are most commonly due to environmental causes (i.e. pollen) and can start suddenly. Benadryl is usually helpful in these cases, so it may be mange. Mange is caused by a microscopic mite that burrows under the skin. This tends to be very itchy. They usually get this from other animals. It's best to have a vet check the skin. They can check for mange and give better treatment for allergies. For now it's best to give him a bath with cool water using a dog shampoo with oatmeal or aloe as an ingredient. I hope that helps and Dozer gets better soon.

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    Answered By David Elbeze, DVM, MRCVS

    Veterinarian

    Published on June 26th, 2017

    This is probably an acute allergic reaction . those reactions tend to resolve within 48 hours without treatment. if the swelling becomes too large or if your dog is lethargic, take Zoey to the vet in order to get an antihistamine injection.

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    Answered By David Elbeze, DVM, MRCVS

    Veterinarian

    Published on December 3rd, 2016

    This is probably an allergic reaction due to an insect bite or a plant outside. those reactions tend to resolve within 48 hours without treatment. if the hives becomes too severe or if your dog is lethargic, take her to the vet in order to get an antihistamine injection.

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    Answered By Jennifer Summerfield, DVM CPDT-KA

    Veterinarian, Certified Dog Trainer

    Published on April 23rd, 2017

    Poor Peppermint Pattie! Hives are usually a sign of some type of allergic reaction - this can be a serious problem on some cases, especially if she is also lethargic and not feeling well. Since the Benadryl didn't help, I'm afraid she really needs to be seen by a vet right away - she may need an injectable steroid to treat the reaction. I would recommend taking her to your nearest emergency vet for an exam and treatment.

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