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My 45lb dog ate 300mg Benadryl. Is this dose dangerous for her?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed Medium (23 - 60lb) | Female | 10 months and 26 days old | 45 lbs

My 40-50lb dog ate 300mg of Benadryl. Will she be alright?

5 Answers

Most Helpful Answer

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Answered By Karly Macon, DVM, MS, CVA Certified Veterinary Acupuncturist

Veterinarian

Published on October 27th, 2017

This is about twice as much benadryl as I would give a dog for allergies or a reaction but this is not a toxic drug and Sadie should be just fine. She may be very sleepy with this dose, however. As long as she doesn't start vomiting or having uncontrollable diarrhea, and seems like her normal self (aside from being drowsy), she should be ok and no need to panic. Hope that helps!

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10Pet Parents found this answer helpful

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    Answered By Vanessa Yeager DVM MPH

    Veterinarian

    Published on

    Hi and thanks for posting! 300mg of Benadryl for her weight range is quite a bit. While Benadryl is considered fairly safe, when a pet receives way too much of it, it can cause extreme lethargy, diarrhea, vomiting, disorientation, decreased heart and respiratory rate, and seizures. 300mg for her body weight is about 4 times the amount she could receive normally. My best advice is to call the Pet Poison Helpline for further guidance. You may need to take Sadie into an emergency clinic to induce vomiting if it has been less than 2 hours since ingestion. Pet Poison Helpline: 855-764-7661 Best of luck to you and Sadie!

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    5Pet Parents found this answer helpful

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    Answered By Jennifer Summerfield, DVM CPDT-KA

    Veterinarian, Certified Dog Trainer

    Published on August 30th, 2020

    Hi there. This is still within the published dosage range for Benadryl in a dog this size, so I would not expect it to cause any significant problems. She may be drowsy for the next few hours (or may be jittery and restless since some dogs have the opposite reaction to Benadryl, just like humans!), but otherwise I would expect her to be just fine. :)

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    Answered By Tomasz Wnuk

    Veterinarian

    Published on August 2nd, 2021

    Hello and thank you for contacting Petco Pet Education Center, formerly Petcoach. This dose of Benadryl may produce sleepiness and lethargy for a few hours but there will not be any more serious symptoms of the overdose. You just need to monitor Hope at home for the next few hours to make sure she is OK.

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    Answered By Laura Johnson VMD

    Veterinarian

    Published on March 24th, 2018

    Hi, thanks for using PetCoach! I never go over 75mg even if the dog weighs over 75 pounds. I would give 2.5- 3 tablets of the 25 mg benadryl personally every 8 hours. https://www.petcoach.co/canigive/dog/benadryl/ Have a great weekend!

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