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Diphenhydramine—more commonly known by the brand name Benadryl—is an antihistamine that people commonly use for both allergies and the common cold. We aren’t the only ones who get stuffy and sniffly when allergy season rolls around, though; our canine companions can also suffer from symptoms of allergies.

Since we know that these symptoms are no fun, it only makes sense that proud pet parents would want to find some way to provide their dogs relief from allergies and colds. Which begs the question: Is Benadryl for dogs safe?

Benadryl for Dogs: Is It Safe?

In most cases? Yes, but with caveats.

Firstly, it’s important to know that, like people, not all dogs will react to this medication the same way. So, while Benadryl for seasonal or environmental allergies might be effective for some dogs, it won’t work for all dogs.

Secondly, Benadryl is merely for mild seasonal allergies and the like. That means if your furry friend is experiencing severe symptoms of an acute reaction—like a swollen face or breathing problems—you need to take them to a vet right away.

Thirdly, there is a limit to how much Benadryl you can safely give your dog. Go over this limit, and there can be devastating consequences.

Fourthly, you need to exercise caution when giving your dog Benadryl or its generic form, diphenhydramine. Why? Because sometimes over-the-counter (OTC) medications have different formulas. That means you need to check whatever OTC remedy you’re getting to ensure it only has diphenhydramine as its active ingredient. Never give your dog anything with the artificial sweetener xylitol.

Fifthly, as is the case with all prescription and OTC medications, it’s always best to consult with a vet before you ever give your dog any amount of Benadryl. This consultation is especially important if your pet already takes other kinds of medications or has a pre-existing health condition.

(Note that this is not a complete list.)

Can You Kill your Dog with Benadryl?

As is the case with any medication, too much Benadryl can be lethal.

Overdose Side Effects

According to Veterinary Place, symptoms of overdose include:

  • Abnormal heartbeat
  • Breathing problems
  • Confusion
  • High blood pressure
  • High fever
  • Intense fatigue
  • Muscle tremors

According to Merck Manual, specific symptoms of Benadryl overdose in dogs include:

  • Depression
  • Excessive saliva
  • Hyperactivity
  • Rapid heart rate
  • Rapid breathing

How Many mL of Benadryl Can I Give my Dog?

The general rule of thumb for using Benadryl (oral tablets) for dogs is 1 mg per pound, taken every 8 to 12 hours. That means a 25-pound dog should not receive more than 25 mg of Benadryl in a single 8 or 12-hour period.

For liquid formulas, a teaspoon is roughly 5 mL. According to Veterinary Place, the recommended dosage for these formulas is 0.4 mL/lb. Now, the pediatric Benadryl liquid formula contains 12.5 mg/5mL, which averages out to roughly 2.5 mg/mL. In this scenario, a 25-pound dog would therefore take no more than 10 mL.

Can I Use Generic Benadryl for my Dog?

Benadryl is the brand name for the generic drug diphenhydramine HCL. It should be safe for dogs to use so long as it does not contain active ingredients that are dangerous for dogs. Typically, it’s best to stick to formulas that use diphenhydramine as the sole active ingredient.

Always make sure anything you give your pet contains no xylitol, as this artificial sweetener can kill dogs.

Final Thoughts

The U.S. Food and Drug Administration (FDA) has not approved the use of Benadryl for dogs. That being said, many veterinarians in the United States commonly use Benadryl and its active ingredients for dogs for purposes that include alleviating seasonal allergy symptoms. Some pet owners may opt to use Zyrtec for dogs instead. It’s always best to consult a veterinarian before giving your pet any sort of prescription or OTC drug; however, most practices have found that 1 mg of Benadryl (oral tablet) per pound is typically a safe dosage.

Disclaimers: This article does not constitute professional veterinary advice, nor can it replace the advice of a licensed veterinarian.

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