Skip to main content

Can you give a dog Benadryl? You’d better follow the correct dosage guide

Just like us, dogs can suffer from allergies. While we can use a nasal spray or take an allergy medication, our dogs rely on us to treat their symptoms. Diphenhydramine, the generic name for the widely used name brand Benadryl, is commonly used by veterinarians to treat seasonal allergies, anxiety, and even motion sickness. Have you ever wondered, “How much Benadryl can I give my dog?” We’ll walk you through everything you need to know about giving dogs Benadryl, from the correct dosage to potential side effects. Here’s the information.

A Bloodhound sneezing as autumn leaves fall around him.
Image used with permission by copyright holder

Benadryl dosage for dogs 

Always speak to your vet before giving your dog any medication or supplements. Because your vet knows your pup’s medical history, they can make the proper recommendations. Benadryl should not be used if your dog:

  • Is pregnant or nursing.
  • Has glaucoma.
  • Suffers from cardiovascular disease.
  • Has been diagnosed with low blood pressure.
  • Is taking certain medications.
  • Has hypothyroidism.
  • Has been diagnosed with seizure disorders.

Benadryl should also not be used as the sole form of treatment for anxiety. While it’s great to have on hand in a pinch for high-stress situations, we recommend working with your vet — or a professional trainer — to get to the bottom of your dog’s anxiety. If your vet gives you the all-clear, you can give your dog Benadryl for allergies or anxiety or use it as a mild sedative while traveling. You should administer 2–4 milligrams per kilogram or 0.9–1.8 milligrams per pound of body weight two to three times a day. In other words, if your dog weighs 50 pounds, you’ll need to give him 50 milligrams of Benadryl up to three times a day to manage his symptoms.  

Is 25 milligrams of Benadryl safe for a dog? 

According to the Merck Veterinary Manual, one 25-milligram tablet of Benadryl two to three times daily is the correct dose for a 25-pound dog. So, if your pup weighs 25 pounds or over, then a dose of 25 milligrams several times a day is perfectly safe. Small dogs should be given children’s liquid Benadryl, as it contains a lower concentration of diphenhydramine and makes it easier for you to administer the correct dosage to your pup.

A Golden Retriever wearing a scarf and holding a handkerchief in his mouth.
Image used with permission by copyright holder

How much Benadryl should I give my 70-pound dog? 

As a general rule, you should administer 1 milligram per pound of body weight. A 70-pound dog will take 70 milligrams of Benadryl. Most Benadryl tablets come in 25-milligram and 50-milligram tablets, so you’ll need to section one of the tablets — or use children’s liquid Benadryl — to give your pup the correct dose. 

Why is Benadryl good for dogs?

Benadryl is an antihistamine, which improves allergies, motion sickness, and inflammation. Benadryl treats allergy symptoms by blocking H1 receptors, which receive signals from allergy-causing histamines. Many veterinarians recommend the use of Benadryl for anxiety caused by stressful situations, car sickness, seasonal allergies, food allergies, and allergic reactions to heartworm treatments. While it’s useful for treating motion sickness and anxiety, Benadryl is most commonly recommended for allergic reactions. According to VCA Hospitals, “Most allergens are proteins from plants, insects, animals, or foods.” Allergies are relatively common in dogs and usually appear when your pup is around 6 months old. Ask your vet if Benadryl can help your dog if he suffers from symptoms like these:

  • Coughing and sneezing
  • Discharge from the eyes
  • Dry, itchy skin
  • Runny eyes and/or nose
  • Hives and welts
  • Wheezing

You’ll also want to keep an eye out for digestive issues, as some food allergies manifest through nausea, diarrhea, and vomiting. 

Potential side effects and complications

While Benadryl is generally well tolerated, some dogs have adverse reactions to antihistamines like diphenhydramine. Dry mouth, extreme fatigue, diarrhea, vomiting, hypersalivation, increased heart rate, rapid breathing, and problems urinating have all been documented in some dogs. In ultrarare cases, Benadryl can have a paradoxical effect and may cause hyperactivity instead of drowsiness. Because of the possible side effects, we recommend starting off with a low dose until you know how well your pup tolerates Benadryl. Take your dog to the vet immediately if he appears to be in distress. Although Benadryl poisoning is rare, it requires prompt medical attention to ensure the best possible outcome. 

A black and white French bulldog yawning on a sofa.
Image used with permission by copyright holder

Benadryl is a relatively safe drug you can administer at home to help treat your dog’s anxiety and allergy symptoms. You should always consult your veterinarian before administering any drug. Please remember to store all medications out of your dog’s reach, and if you give him Benadryl for anxiety, work with your vet to find ways of managing the issue so your pup doesn’t become dependent on medication. 

Editors' Recommendations

Mary Johnson
Contributor
Mary Johnson is a writer and photographer from New Orleans, Louisiana. Her work has been published in PawTracks and…
Off-leash dog training is easy if you follow these 5 tips
These tips will make this process smoother
Puppy learning to heel

We’re going out on a limb here, but it’s safe to say that if you’ve ever caught the look on a dog’s face when he’s running off leash at the dog park, you’ve caught a glimpse of what pure bliss looks like.

As a pet parent, it’s only natural to want to see that expression more often. And, without disparaging the leashed walk around the neighborhood, your dog would probably tell you he’d prefer being off leash more often. Is that possible, given local leash laws and all the mischief your untethered pet can get himself into? Perhaps, if he is well trained.

Read more
Why do dogs eat cat poop? And how you can get them to stop
These tips will stop your pup from eating cat doo-doo
Dog wears a yellow sweater and looks at the camera

Sometimes you might think you hear your cat using their potty, but when you go into check, it's actually the dog eating cat poop. Gross! While it seems pretty revolting to us, dogs sometimes eat poop, the feline variety included. Coprophagia, which means eating poop, shows up reasonably frequently in pups, and certain diets, environments, and even breeds can make this act more likely (research says hounds and terriers are the groups most likely to chomp poop, in general).

So why do dogs eat cat poop, and what should you do about this behavior? Read on for a few things to check and a couple of tips to prevent this extra meal.
Why do dogs eat cat poop?
Theories abound, but it turns out lots of different mammals eat poop, their own and others'. One possibility is that not all nutrients fully digest when they go through our systems, which means there are plenty of vitamins to have by consuming feces. Sometimes, these cravings result from a nutrient-deficient diet that is easy to fix by changing up your dog's food.

Read more
Do dogs know they’re dying? Here’s what experts say about a dog’s final days
This is what a dog's last days might look like
A woman hugs and kisses her senior dog

No one wants to think about their dog’s final moments, but it’s an inevitable part of life that every pet parent will have to face. Hopefully, though, knowing what to expect can replace some of the fear and uncertainty with a sense of peace. Thinking through this life transition may be emotionally taxing, but asking the important questions (such as, do dogs know they’re dying? Do dogs fear death?) can make the process as easy as possible for everyone — especially you.

Take a deep breath, give your dog a little love, and scroll on if you’re feeling ready to learn about this important — yet difficult — time. We’ll let you know how to care for your senior dog, how your veterinarian will be helpful during this time, and what to expect as your dog's final moments draw near. Trust us — you're not in this alone.

Read more