Benadryl For Dogs: Safe Dosages And Uses

If you’ve ever had allergies or an allergic reaction, you’ve likely turned to Benadryl for relief.

Benadryl is an antihistamine that alleviates allergy symptoms including sneezing, runny nose, watery eyes and itchy nose or throat in people. And while it has not been approved by the FDA for use in animals, it’s also used off-label in veterinary medication to help treat allergies, allergic reactions and motion sickness among other things in some animals, including dogs.

Benadryl is relatively affordable and considered a safe treatment for dogs. And for many pet owners, the cost of the medication can be covered by pet insurance, depending on individual policy coverage.

Here’s a look at Benadryl and what to know about giving it to your dog.

What Is Benadryl Used for in Dogs?

Benadryl is an antihistamine that is commonly used in dogs to help manage symptoms from allergies. Benadryl is just one brand name for diphenhydramine; others include Banophen, Diphenhist, Unisom and Sominex.

“The active ingredient diphenhydramine can help alleviate symptoms by blocking histamine receptors, which cause itching and inflammation,” says Dr. Kathryn Dench, veterinary surgeon and advisor for Gentle Dog Trainer, a site dedicated to helping owners raise happy and healthy dogs.

Benadryl is also used for the following:

• Treating allergies: Benadryl is commonly used as a first line of defense for patients with flea and food allergies or eczema. It’s also used to treat reactions to bug bites, vaccinations and for topical reactions to antiseptics during surgery.
• Sedation: While some veterinarians may prescribe Benadryl as a sedative, there are mixed opinions on how effective it is.
• Motion sickness: Some believe Benadryl to be effective in treating motion sickness due to its antiemetic properties, but again, there are mixed opinions on whether this is truly effective.

“Interestingly enough, despite the widespread usage among veterinarians, the effectiveness of Benadryl in both dogs and cats is not clear cut,” says Dr. Mathieu Glassman, V.M.D., founder and CEO of Dr. Cuddles, a pet-care company. He adds that some studies show the medication to be ineffective for all of the uses listed above.

Is Benadryl Safe To Give to Dogs?

When used under the direction of your veterinarian, Benadryl is safe to give to dogs.

“Benadryl, an antihistamine, can indeed be safe for dogs when used under veterinary guidance,” Dench says. “It’s commonly used to manage various issues in dogs, primarily allergies, itching and even mild anxiety.”

But before owners start pulling out their Benadryl from the medicine cabinet, it’s important that they speak to their veterinarian first.

Based on your dog’s health and medical history, your vet will determine whether it’s safe and warranted to give your dog Benadryl.

When Can Owners Give Benadryl to Dogs?

Benadryl should only be given to dogs after it has been recommended by a veterinarian.

Owners should be careful to follow their vet’s instructions to avoid giving their dog too much Benadryl, which can cause adverse side effects.

After consulting with a veterinarian, it’s safe to give dogs Benadryl for the following reasons:

• Allergies, including skin and environmental allergies
• Emergency treatment for severe allergic reactions (before going to the vet)
• Reduce symptoms of insect bites or stings
• Alleviate inflammation or itching from allergies
• Treat hives, runny nose and eyes, coughing and sneezing
• Treat anaphylactic reactions from vaccines
• Reduce travel anxiety and motion sickness

“And, of course, when administering any medication to your pets, it’s always best to consult your veterinarian if you’re unsure,” Glassman says.

When Owners Shouldn’t Give Benadryl to Dogs

It’s always best to talk to your veterinarian about all medications and supplements your dog is currently taking, as well as any known allergies when it comes to medications.

Benadryl should be avoided in dogs with the following:

• Certain health conditions like glaucoma, cardiovascular disease, high blood pressure, liver disease or hyperthyroidism
• Experiencing seizures
• Allergies to Benadryl or other antihistamines
• That are pregnant or nursing
• Are taking conflicting medications, including some antidepressants, other antihistamines, potassium supplements and certain gastrointestinal medications that would be prescribed by a veterinarian

What Is a Safe Benadryl Dosage for Dogs?

A safe dosage of Benadryl will depend on several factors, including the dog’s size and weight.

Benadryl comes in a tablet, capsule, chewable, oral liquid or liquid injection, says Dr. Michael Fleck, D.V.M., veterinarian and co-host of the radio show, The Pet Buzz.

The general dosing guidelines for dogs is 1 to 2 milligrams for every 1 pound of body weight, Glassman says.

Can Dogs Overdose On Benadryl?

It is possible to overdose a dog on Benadryl.

“When it comes to dosages, a veterinarian’s guidance is crucial,” Dench says. “Giving the correct amount is vital, as overdosing can be harmful.”

Symptoms of dogs that have been given too much Benadryl include::

• Central nervous system stimulation, including excitement and seizures
• Central nervous system depression, including lethargy, and in extreme cases, coma
• Anticholinergic effects, including reduced saliva and tear production, urine retention and constipation
• Cardiovascular abnormalities, including tachyarrhythmia or fast heart rate
• Respiratory depression
• Lethargy
• Vomiting
• Dilated pupils
• Seizures

Can I Give My Dog Benadryl Every Day?

Benadryl can be given two to three times a day to treat allergies and allergic reactions, but isn’t intended for extended daily use.

“Is it safe to give Benadryl every day? Yes. Is it necessary? Probably not,” Glassman says. “If a pet owner is wanting to give Benadryl daily to address an issue, they likely should seek veterinary help as there are likely many more effective treatments that could be considered.”

Glassman adds that veterinarians will sometimes use Benadryl on a daily basis in animals that have mast cell disease (a cancer of cells that release histamine) to block histamines. In these cases, continuous professional supervision is required.

Benadryl Side Effects for Dogs

When using Benadryl, dogs generally have a euphoric or sleepy feeling with a noticeable dry mouth, Fleck says.

Although considered a safe medication, your dog can still experience negative side effects on Benadryl, including:

• Central nervous system depression, including lethargy and sedation
• Constipation, dry mouth and urinary retention
• Gastrointestinal effects, including diarrhea, vomiting and anorexia
• Excitement and agitation

How Long Does It Take for Benadryl To Start Working?

Generally, Benadryl starts working within 30 to 60 minutes of giving it to a dog.

How the Benadryl is administered (oral liquid, tablet, capsule, or injection) will determine how quickly it takes effect.

But keep in mind that not all dogs will react to the medication in the same way, and it may take longer for it to take effect in other dogs.

How Long Does Benadryl Stay in a Dog’s System?

In a dog with normal liver and kidney function, the effects of Benadryl typically last between four and eight hours.

The medication itself will stay in the dog’s system for slightly longer than that, Glassman says.

Bottom Line

Under the care and supervision of your veterinarian, Benadryl is a safe and effective drug for treating allergies and allergic reactions in your dog.

But before you turn to your personal stock of the antihistamine, it’s important to consult your veterinarian who will consider your dog’s full medical history and determine whether Benadryl is an appropriate treatment for your dog.