Benadryl for Dogs: What To Know From a Vet

Four minutes
Nov 13, 2023

While it may be second nature to treat your allergies with medication, is Benadryl safe for dogs? The short answer is yes, you may be able to give your dog Benadryl. But it’s a little more complicated than just giving them the same form and dosage you take.

Benadryl is the brand name for diphenhydramine, an antihistamine that crosses the blood-brain barrier and blocks certain receptors in the body from registering histamines that are present.3 It can be used to relieve symptoms associated with various types of allergies as well as travel anxiety and motion sickness.

Read on to learn more about what it can treat in dogs, when you shouldn’t give them the medicine, and how much Benadryl for a dog is safe.

Can You Give Your Dog Benadryl?

If you’ve consulted your veterinarian first, Benadryl can usually be given to your dog at home.4 There are some instances when your dog shouldn’t have Benadryl as it could make them more anxious, interfere with other medications, or complicate certain health conditions, so it is important that your vet weighs in before giving your pup a dose. Make sure you have the correct form and dosage (more on that later).

Is it Safe To Give Your Dog Benadryl?

Benadryl is typically safe for most dogs when given the proper dosage, although it’s not yet approved by the Federal Drug Administration (FDA) for veterinary use.3 While considered safe for most dogs, it may be best to avoid giving your dog Benadryl if they have any of these conditions3,4:

  • Cardiovascular or lung diseases
  • Glaucoma: This is an eye disease that causes the natural pressure in the eye to increase.5
  • Low or high blood pressure
  • Pregnancy
  • Hypothyroidism: This condition when the thyroid is underactive and slows the dog’s metabolism.6
  • Seizure disorders

Talk to your vet before giving your dog Benadryl to make sure none of these conditions apply, and make sure they won’t interfere with any medications your dog is on. Just like with any new food or medication, watch your dog closely after you give them Benadryl to look for signs of adverse reactions.

What Can Benadryl Treat in Dogs?

Just like with humans, Benadryl can be given to dogs to help treat symptoms related to allergies such as environmental and seasonal allergies, reactions to certain spider and insect bites, skin allergies, and food allergies.

Benadryl can be used to help reduce allergy symptoms including3:

  • Runny eyes and nose
  • Coughing and sneezing
  • Redness in the eyes and skin
  • Hives
  • Inflammation and swelling
  • Anaphylactic reaction

If your dog displays signs of a severe allergic reaction (facial swelling or difficulty breathing) before or after giving them Benadryl, take them to the vet immediately.

Can you use Benadryl to treat anxiety?

You may have heard about pet parents using Benadryl to help calm their dog due to its mild sedative properties. While it may work for some dogs, others may actually become more anxious after giving it to them.4 If your dog has travel anxiety or general anxiety, talk with your vet to come up with the right treatment plan for them.

Benadryl Dosage for Dogs

Each dog is different, so it’s best to check with your vet to see how much Benadryl you can give your dog. Some Benadryl may be mixed with other ingredients that are toxic to dogs — like alcohol, decongestants, or Tylenol. So read the label and make sure the Benadryl or generic versions you give them only contain diphenhydramine.

Experts recommend 2 – 4 milligrams (mg) of Benadryl per kilogram of body weight (or 0.9 – 1.8 milligrams per pound) every 8 – 12 hours.7 Using these numbers, and making it easier to remember, 1 mg of Benadryl per pound of body weight, given 2 – 3 times a day may be considered a practical dose.4 So if your dog weighs 20 pounds, 20 mg of Benadryl given 2 – 3 times a day may work.

Children’s Benadryl pills have smaller dosages than adult pills, which may make it easier to adjust the dosage you need and easier for your pup to swallow, especially if you have a small dog. Aside from human Benadryl, you may be able to find pet versions, with the Benadryl for dogs dosage being around 10 mg per pill, making it even easier to measure.

Benadryl to avoid

Veterinarians generally recommend avoiding time-release Benadryl at all costs.3 That type is designed for human stomachs and may break down differently in dog stomachs. It can also be chewed open and ingested too quickly, increasing the risk of an overdose. You may also want to avoid liquid versions (especially if it contains sodium, which can be poisonous to dogs) because it is absorbed differently than pills and affect the dosage your dog needs.3,4

Benadryl overdose

Even if you’re following your vet’s dosage instructions carefully, there’s still a chance your dog could experience an overdose. When an overdose happens, your dog’s central nervous system can go into overdrive and cause rapid heartbeat, agitation, dilated pupils, constipation, and even seizures.3

If you notice any of these signs, call ahead and bring your dog to the vet immediately.

Side Effects of Benadryl

Some dogs may experience side effects from Benadryl. If they do, they’ll typically occur in the first hour or so after giving them a dose. Some of these potential side effects include3:

  • Either hypersalivation or dry mouth
  • Drowsiness
  • Urinary retention
  • Rapid breathing
  • Increased heart rate
  • Vomiting or diarrhea
  • Increased or decreased appetite

Get the Best Care and Protect Your Wallet

Whether your pup is curious and gets stung by a bee, adventurous and runs through some poison nettle, or has seasonal allergies that flare up, they may end up in situations causing them discomfort.

With your vet’s advice, Benadryl may be used to help treat some of these allergy symptoms, but if further medical attention is needed, a surprise trip to the vet could cost a pretty penny. Your dog deserves the best care, and signing up for a MetLife Pet Insurance1 dog insurance policy may help you get reimbursed for those vet bills2 — putting money back in your wallet for the next adventure together. Get your free quote today.

Protect your Dog

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Dr. Hunter Finn is an integrative veterinary expert first, and social media star second. America’s favorite veterinarian owns Pet Method in McKinney, Texas, where he cares for pets while prioritizing their emotional well-being. When he’s not at his clinic, he’s starring in viral videos on TikTok (2 million followers) and Instagram (500K followers) — where he’s been known to snuggle puppies and conquer the latest dance trends.

Nothing in this article should be construed as financial, legal, or veterinary advice. Please consult your own advisors for questions relating to your and your pet’s specific circumstances.

1 Pet Insurance offered by MetLife Pet Insurance Solutions LLC is underwritten by Independence American Insurance Company (“IAIC”), a Delaware insurance company, headquartered at 485 Madison Avenue, NY, NY 10022, and Metropolitan General Insurance Company (“MetGen”), a Rhode Island insurance company, headquartered at 700 Quaker Lane, Warwick, RI 02886, in those states where MetGen’s policies are available. MetLife Pet Insurance Solutions LLC is the policy administrator authorized by IAIC and MetGen to offer and administer pet insurance policies. MetLife Pet Insurance Solutions LLC was previously known as PetFirst Healthcare, LLC and in some states continues to operate under that name pending approval of its application for a name change. The entity may operate under an alternate, assumed, and/or fictitious name in certain jurisdictions as approved, including MetLife Pet Insurance Services LLC (New York and Minnesota), MetLife Pet Insurance Solutions Agency LLC (Illinois), and such other alternate, assumed, or fictitious names approved by certain jurisdictions.

2 Provided all terms of the policy are met. Application is subject to underwriting review and approval. Like most insurance policies, insurance policies issued by IAIC and MetGen contain certain deductibles, co-insurance, exclusions, exceptions, reductions, limitations, and terms for keeping them in force. For costs, complete details of coverage and exclusions, and a listing of approved states, please contact MetLife Pet Insurance Solutions LLC.

3 “Benadryl for Dogs,” American Kennel Club

4 “Can I Give My Dog Benadryl and If So, How Much?,” PetMD

5 “Glaucoma in Dogs,” VCA Animal Hospitals

6 “Hypothyroidism in Dogs,” VCA Animal Hospitals

7 “Antihistamine Dosages,” Merck Manual Veterinary Manual

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