Benadryl for Dogs

Know your dog’s weight and how to recognize a mild allergic reaction before giving Benadryl to dogs.


Benadryl is an over-the-counter human medication you can use for dogs with an allergic reaction, such as from a bee sting. Benadryl, or generic diphenhydramine, is an antihistamine approved for people.

Benadryl is not FDA-approved for use in dogs, but it is commonly used off label. Benadryl can be purchased as 25-milligram (mg) tablets and 50-milligram “extra strength” tablets. You must be certain which Benadryl you have before giving it to your dogs. Most veterinary dosages are based on the 25-mg tablet.

In general, Benadryl doses for dogs—provided the dog is not vomiting or showing signs of diarrhea, weakness, or collapse—is approximately 1 to 2 mg of diphenhydramine per pound of body weight. That means a full 25-mg tablet is appropriate for a dog weighing 14 to 28 lbs. PreventiveVet has a clickable dosage chart. Just enter your dog’s weight, and it tells you how much diphenhydramine you can give the dog, based on 25 mg tablets.

Warning: If using any human diphenhydramine or Benadryl product, check how much diphenhydramine it contains and all other ingredients. Some products contain decongestants, which are dangerous for dogs. In addition, products containing alcohol or xylitol can harm or kill your dog.

While Benadryl often makes people drowsy, it has less of an effect on dogs. Still, it can reduce anxiety for some dogs and may help with nausea, such as car sickness. Be forewarned, however, that some dogs become anxious and hyper from Benadryl. If you’re looking for anti-anxiety meds for your dog, talk with your veterinarian.

Benadryl helps manage mild symptoms of seasonal allergies. For dogs, that often means itching and/or hives. You may see the dog rubbing his face, ears, and eyes, and maybe sneezing. Benadryl helps relieve inflammation and reduce swelling.

Always check with your veterinarian before giving your dog this medication, as it may not be appropriate for your individual dog based on your dog’s health, other medications, and what you think you’re treating. Include Benadryl in your pet first-aid kit but be proactive and get the specific dose for your dog from your vet ahead of time and put it with the drug.


  1. You can buy liquid diphenhydramine for dogs from a compounding pharmacy….my vet ordered it for my dogs to keep in the emergency kit. It came in handy for me when one of my foster puppies was stung on the eyelid one Saturday afternoon. I weighed him and drew up the dose in a syringe…so he had the dose in less than 2 minuted after the sting (his eye was swollen shut and I still considered a trip to the emergency vet). I used a cold compress and held him on my lap the rest of the day…..after about 5 hours the swelling subsided and he was OK.