Many human medications are toxic to dogs, but Benadryl is an exception. So, if you're asking yourself, "Can I give my dog Benadryl?," the answer is generally yes. But, there's a lot more you need to know before you hand over that pink pill. 

Benadryl is the most common brand name for allergy medications that contain the active ingredient diphenhydramine. Not every variety of Benadryl is safe for dogs. Dogs also metabolize medicine differently from humans, so the dosing instructions on the side of the box won't work for your furry friend. Plus, Benadryl can interact with other medications and cause adverse reactions in dogs with certain pre-existing conditions. 

Below, we'll give you an in-depth look at how this medication affects your best friend. But, before you give your dog Benadryl, talk to your vet to make sure it's safe for your pet's specific needs. This information is for educational purposes only and is not a substitute for veterinary advice. 

How Does Benadryl Work in Dogs?

Benadryl works the same way in dogs as it does in people — by blocking histamine.

When your dog comes into contact with an allergen, their immune system produces histamine, a natural compound that tries to flush allergens out of the body. If your pet has environmental allergies, histamine is responsible for your dog's sneezingrunny nose, watery eyes, and itchy skin. If they experience food allergieshistamine can cause hives, diarrhea, and vomiting in dogs. And during a severe allergic reactionhistamine is responsible for swelling and anaphylactic shock. 

The active ingredient in Benadryl, diphenhydramine, bonds with a specific type of histamine receptor, known as an h1 receptor. When diphenhydramine is bonded to these receptorshistamine can't bond with them and can't cause an allergic reaction.  

What Can I Give My Dog Benadryl For?

can I give my dog Benadryl: dog scratching himself outdoors

The most common use for Benadryl is allergy treatment. But, this medicine is also effective against a number of conditions, including: 

  • Allergies: Benadryl can help treat and prevent allergic reactions in dogs. It also eases the symptoms of allergies, including sneezing, watery eyes, itchy skin, and runny nose
  • Insect bites: Benadryl can help ease the swelling and itchiness that often accompany insect bites. If your dog is having a bad reaction to mosquito bites, fire ant bites, or a bee sting, call your vet and ask if it's okay to treat them with Benadryl. If, however, your dog was stung or bitten by an unknown insect or a snake, go to your vet immediately. Your pet may be reacting to the animal's venom.
  • Motion sickness: If your dog often gets sick on long car ridesBenadryl may help prevent motion sickness. Ask your vet if it's okay to give your dog this medication before your next road trip. 
  • Anxiety: As pet owners, we often want to ease our pet's fear during thunderstorms or fireworks. Benadryl has a sedative effect, which can help keep our pets calm. However, you should always talk to your vet before using Benadryl as a sedative. It may not be the most effective treatment for your pet's anxiety, and in a small percentage of dogs, it can actually cause hyperactivity instead of sedation
  • Side effects of heartworm treatment: Heartworm treatment can cause a variety of uncomfortable side effects. Vets often prescribe Benadryl alongside this treatment to ease the side effects and keep your pet comfortable. If your dog is being treated for heartworm, ask your vet about using Benadryl at home.  

When Should I Avoid Giving My Dog Benadryl? 

While Benadryl is good for treating occasional allergic reactions, it shouldn't be your drug of choice if your pet has on-going food, environmental, or seasonal allergies. Because it causes drowsiness and acts as a sedative, regularly giving your pet Benadryl can decrease their quality of life. They won't be able to enjoy their daily activities or time with their family if they're mildly sedated. 

Instead, try allergy testing to identify what's causing your dog's symptoms. For environmental and seasonal allergies, support your pet's immune system with an all-natural allergy supplement for dogs, and talk to your vet about alternative antihistamines that won't cause drowsiness

You should also avoid giving your dog Benadryl if they're having a serious allergic reaction that includes swelling or difficulty breathing. Instead, take your dog to your vet or the nearest 24-hour emergency vet immediately. 

How Much Benadryl Can I Give My Dog?

can I give my dog Benadryl: dog looking at a person holding a pill

Dogs metabolize Benadryl faster than people, so Benadryl dosage for dogs is higher than it is for us dog owners. But, it's still possible to cause a Benadryl overdose if you don't give the correct dosage of Benadryl or the correct formulation of this medicine. Always talk to a qualified doctor of veterinary medicine (DVM) before giving your dog Benadryl. 

Make sure you check the other ingredients in your Benadryl before you share it with your pet. Some formulas contain decongestants, Tylenol, or alcohol, which can be toxic to dogs. The only active ingredient in Benadryl for dogs should be diphenhydramine. Check the full list of ingredients to ensure the formula doesn't contain alcohol. 

Never give dogs time-released Benadryl tablets because they can cause an overdose. And talk to your vet before giving your dog liquid Benadryl because the dosage instructions will be different. 

According to the Merck Veterinary Manual, the proper dosage of diphenhydramine for dogs is 1 mg per pound of body weight. A standard Benadryl tablet contains 25 mg of diphenhydramine, so a 25-pound dog should take one tablet. 

If you have a small dog, it can be harder to get the dosage right. Children's Benadryl tablets may help because they typically contain half the amount of diphenhydramine — 12.5 mg — as a typical Benadryl tablet.

If you're worried about finding the right dosage for your dog, your vet can help. They can tell you the type and amount of over-the-counter Benadryl to give your dog. And often they can give you a prescription for dog-specific medication, formulated for your pet's size. 

Will My Dog Experience Side Effects? 

Even though Benadryl is considered safe for dogs, it comes with a variety of potential side effects, including:  

  • Drowsiness  
  • Dry mouth
  • Urinary retention 
  • Rapid breathing   

In addition to these common side effects, your dog can also experience more severe side effects. While it's rare, some dogs can have an allergic reaction to the Benadryl itself. If you notice any of these symptoms, contact your vet or an emergency vet immediately. They can be signs of a Benadryl allergy or overdose: 

  • Elevated heart rate
  • Difficulty breathing
  • ​Swelling
  • Skin rashes
  • Dilated pupils 
  • Diarrhea
  • Vomiting 
  • Agitation 
  • Constipation 
  • Seizures 

What Other Precautions Should I Take?

man and dog high five

In addition to the potential side effects of Benadryl, this medication can interact with other drugs, including anti-coagulants and drugs that suppress the nervous system. If your dog is taking any other medication — regardless of whether it's a prescription or over-the-counter medication — talk to your vet to make sure it's compatible with Benadryl. 

Dogs with certain pre-existing medical conditions — including glaucoma, low blood pressure, pregnancy, lactation, enlarged prostate, thyroid disease, cardiovascular disease, or lung disease — shouldn't take Benadryl. Again, your vet can help you determine whether Benadryl is safe for your dog. 

So, Can I Give My Dog Benadryl? 

While Benadryl isn't right for all dogs, it's generally safe for our furry friends. It's most often prescribed to treat dog allergies, but it can also offer relief if your dog has a reaction to insect bites, experiences anxiety during thunderstorms, or gets motion sickness on long car rides

But, Benadryl isn't a good long-term solution for seasonal and environmental allergies. Because it causes drowsiness, this medication can interfere with your dog's ability to enjoy their daily activities. Instead, look for all-natural remedies, like allergy supplements to support your dog's immune system, or talk to your vet about alternative antihistamines that won't cause drowsiness

For more information on your pet's health and wellness, visit the Native Pet blog


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