Can You Give a Dog Benadryl for Allergies?

Our fur babies are our family, so when they’re unwell with allergies, it’s no wonder we consider using medication that we would use ourselves! 

Yet, ask any vet, and they will tell you to stop and think before you reach for any old thing you have in the medicine cabinet. Humans can react very differently to medicine compared to our cute companions. 

But what if you find your dog is suffering from non-serious allergies?

Diphenhydramine is an over-the-counter drug used to treat motion sickness, anxiety, and allergy symptoms — but, can you give a dog Benadryl for allergies?

dog allergies benadryl.

Can Dogs Take Benadryl for Allergies?

Benadryl — aka diphenhydramine — is an antihistamine that helps us when we’re suffering from allergies. It’s very effective — crossing the blood-brain barrier and easing symptoms rapidly. 

There are, however, side effects that you need to be aware of. These include:

  • Dry mouth.
  • Rapid breathing.
  • Drowsiness.
  • Increased heart rate.

According to the FDA, Benadryl is classified as unapproved for use in animals. That said, it’s often administered or suggested by vets who are happy to give Benadryl for dogs with allergies as the side effects are less adverse than the allergies themselves.

And, while Benadryl is considered OK for canines, the dosage will differ depending on the weight, size, and breed. Hence, always seek professional advice before taking things into your own hands.

How Does Benadryl Help Dogs With Allergies?

This medication is commonly used for mild allergies. For example, you can use  Benadryl for dog skin allergies, dog eye allergies, dog seasonal allergies, and dogs allergic to grass.

The list below gives you an idea of the symptoms Benadryl for dog allergies can help to alleviate:

  • Hives.
  • Coughing.
  • Sneezing.
  • Runny nose and eyes.
  • Swelling and inflammation.
  • Redness.
  • Itchy skin. 

As you can see, there are a number of ways Benadryl can help pet allergies. 

benadryl for dogs with allergies.

How Much Benadryl To Give a Dog With Allergies — Dosage

Now we have identified that Benadryl is an active medication that vets give to our best friends. We turn to the question — how much Benadryl can I give my dog for allergies?

As mentioned, you should always check with your vet before giving your dog any kind of medication. But as a guide, the general rule of thumb is 2-4 mg per kg of a dog’s weight.

 You must not go over or against this recommended dosage as an overdose can cause catastrophic harm to your pooch.

How Often Can You Give a Dog Benadryl for Allergies?

The Benadryl dosage for a dog’s allergic reaction should only be offered two to three times a day, unless told otherwise by a professional. 

If you feel like your dog has had too much, contact your local vet immediately. Signs of an overdose to keep a lookout for include: 

  • Constipation.
  • Agitation.
  • Dilated pupils.
  • High blood pressure.
  • Rapid heart rate.
  • Seizures.

When Not to Give Benadryl for Dog Allergies

For the most part, Benadryl is safe to give to dogs and has few side effects when given correctly. However, there are some bow-wows who have certain health conditions that should not be given Benadryl for dog allergies. These include the following:

  • Glaucoma.
  • Hypotension (low blood pressure).
  • Heart conditions.
  • During pregnancy.
benadryl for dog skin allergies.


Benadryl is used regularly by professionals and can also be used by you at home! It offers relief from the irritation that allergies cause — helping to reduce your tail-wagger’s itchy skin, watery eyes, sneezing fits, and more.

However, the correct dosage is crucial. And, not all dogs benefit from this treatment. Hence, check with your vet before going ahead.  

So, can you give a dog Benadryl for allergies? It’s safe to say that Benadryl can be safely used to treat dogs with allergies — but it would also be advised to keep an eye on your dog when using this medication for the first time.

Benadryl Allergy for Dogs FAQs

Can Dogs Take Benadryl for Allergies?

Yes, you can give your dog Benadryl, provided you have sought dosage advice from a registered vet.

Can Benadryl Cause Seizures in Dogs?

On the whole, Benadryl is an antihistamine that’s well-tolerated within the canine community. However, seizures are a potential side effect.

Will Benadryl Make a Dog Sleepy?

Benadryl can have adverse effects on your dog in the same way as it can on humans. These include sleepiness, dry mouth, sluggishness, or urinary retention.

Can Dogs Be Allergic to Benadryl?

There have been known cases where the drug diphenhydramine can be counteractive in some dogs. If you suspect an allergic reaction to any medication ensure you research Anaphylaxis in dogs and contact your vet immediately.

Is Benadryl Harmful to Dogs?

If administered correctly, generally no. However, excessive amounts can be very harmful to a dog. If you think that your bow-wow has been given the wrong dosage, you may notice symptoms such as:

  • Dilated pupils.
  • Difficulty breathing.
  • Rapid heart rate.
  • Seizures. 

How Long Does It Take for Benadryl to Work in Dogs for Allergies?

Benadryl will normally take around 30 minutes to take full effect and help your dog with allergies. 

What Can I Give My Dog for Allergies Besides Benadryl?

There are a few other antihistamines that may work better for your dog, such as chlorpheniramine, clemastine, hydroxyzine, or Claritin (loratadine).