How Much Benadryl Can I Give My Dog? The Dilemma Is Solved!

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A devoted pet parent, pet store manager and animal shelter volunteer. Read more about me here.

Today I am going to answer one of the most asked questions - how much Benadryl can I give my dog.

Benadryl is a brand name for a med that is also known under its generic name, diphenhydramine. It is one of the most used over the counter medications that vets administer to dog owners to help them ease anxiety if they are afraid of fireworks. If they suffer from motion sickness during a car ride or mild seasonal allergies reaction since the active ingredient is an antihistamine.

However, although Benadryl is generally well tolerated by dogs, you should always consult your vet about using it since it might interact with other meds that your dog is currently on. It is also evident that large and small breeds can't use the same dosage considering the difference in their body weight.

Here's all you should know about Benadryl before giving it to your pooch.

Last Updated: November 28th 2023

What Is Benadryl And How Does It Work?

give benadryl to dog

Benadryl or Diphenhydramine HCL is a first-generation ethanolamine-derivative antihistamine. Diphenhydramine is a receptor antagonist, so that means the drug works by blocking the H1 receptors that receive histamines in the body which are responsible for allergic reactions. This way, the drug relieves symptoms of seasonal environmental allergies such as itching, coughing, inflammation, sneezing, and hives.

When Benadryl is applied topically, it will treat skin conditions that result in pain and itching caused by things such as poison ivy, cuts and burns, and insect bites such as bee stings. It will treat food allergies, insomnia, cold symptoms, runny nose and eyes, motion sickness caused by car rides, separation anxiety, and hay fever when taken orally.

Benadryl in dogs is also used if your doggo went under heartworm treatment. Usually, heartworms' death can trigger an allergic reaction, so you should give your dog Benadryl to ease the symptoms associated with the treatment. Also, Benadryl is beneficial for treating mast cell tumors. In case your dog suffers from a mast cell tumor, the white blood cells degranulate, which triggers the massive histamine release.

Even after you give your dog Benadryl, the body will still produce histamine, but the med will block the receptors from registering the histamine. Benadryl is still not FDA-approved for veterinary use, but it is considered safe for dogs and cats, and it is commonly used in veterinary practices worldwide.

How Many Benadryl Can I Give My Dog?

As with all meds, the right dosage of Benadryl for dogs depends on the exact body weight. Most drugstore diphenhydramine tablets are 25 milligrams, which means one milligram per pound, so one tablet is suitable for a dog that weighs 25 pounds.

Small dogs that weigh under 25 pounds should take the children's liquid Benadryl formula since it is way easier to measure the proper dose of dog liquid Benadryl than Benadryl tablets. Also, kids liquid Benadryl does not contain alcohol compared to the adult version.

There is also a topical form of Benadryl, which is excellent for treating irritated areas and prevent itching. Consult your vet to determine if you need to give your dog a lotion, cream, or gel form.

Veterinarians suggest that you give Benadryl to your dog every eight to twelve hours, and it usually takes 30 minutes to take effect. Never go over two to three times a day. You should expect that the med will slowly start to lose effectiveness if you use the product frequently.

It is always better to administer medication before exposure to allergens, of course, if you are aware of them. Even if symptoms seem to disappear, continue to use the therapy as the vet recommended.

Suppose your dog is suffering from the onset of a severe allergic reaction. In that case, the veterinarian may need to inject an antihistamine under your dog's skin, so the medicine to act more quickly.

What Are The Side Effects Of Benadryl For Dogs?

Like with most other meds, some possible side effects can occur. Usually, side effects occur within the first hour after the usage, so monitor your dog carefully in this period. The potential side effects when administering Benadryl to dogs are:

  • Rapid heart rate
  • Difficulty breathing
  • Drowsiness
  • Dry mouth or hypersalivation
  • Urinary retention
  • Sedation
  • Vomiting
  • Diarrhea
  • Decreased or increased appetite

If your dog suffers from any of the following conditions, consult your vet before using Benadryl:

  • Angle-closure glaucoma
  • Pregnancy
  • High blood pressure
  • Severe heart disease
  • Prostatic hypertrophy
  • Bladder neck obstruction
  • Seizure disorders
  • Allergic lung disease

It is also good to know that Benadryl may react negatively if your dog uses the following drugs:

  • Central Nervous System depressants
  • Epinephrine
  • Heparin
  • Amitraz
  • Furazolidon
  • Selegiline
  • Warfarin sodium

As always, consult your vet before putting your dog on Benadryl since only your vet knows the medical history and potential complications of your pooch. This way, you will minimize any risks, and in case this med is not a possible option, the vet will recommend you the best alternatives to Benadryl.

Benadryl Overdose

Of course, it is possible to overdose on Benadryl. It would help if you learned what signs of an overdose are before it is too late. The signs of overdose are:

  • Rapid heart rate
  • Dilated pupils
  • Agitation
  • Constipation
  • Seizure

If you suspect your dog overdosed on Benadryl or you notice any side effects after usage, contact your veterinarian immediately or any other emergency veterinary hospital. Also, it is possible that some dogs develop an allergic reaction to Benadryl. If you notice symptoms of an allergic reaction or if current allergic symptoms worsen, seek veterinary care immediately.

Can You Kill Your Dog With Benadryl?

Remember that some formulas contain toxic ingredients to dogs, such as alcohol, Acetaminophen, and Pseudoephedrine. Make sure you never give your dogs too much Benadryl. Benadryl's high dosage can cause allergic reactions and hyper-excitability of the central nervous system (CNS), which can be fatal.

What Are Benadryl Alternatives?

Luckily for all the dog parents, Benadryl is not the only solution available for treating dog allergies. Suppose you prefer not to use conventional over the counter medicines on your dog, or your pup experienced any side effects of Benadryl, the solution is in using natural alternatives. 

Several natural alternatives can help you control allergy symptoms, insect bites, and motion sickness. These following natural remedies will provide the same kind of relief as a drug you know under the brand name Benadryl so make sure you check out this list.


The best ally in fighting allergy symptoms like itchy red eyes, runny nose, inflammation, and sneezing is a natural alternative for Benadryl - the quercetin.

Quercetin is a flavonoid found in the peels of fruits and veggies, and it contains anti-inflammatory

anti-oxidant and antihistamine properties.

The recommended dosage of quercetin for humans that weigh 150 pounds is 1000 milligrams. This formula will help you convert the right dosage for your dog by taking your doggos weight, multiply it by 1000, then divide by 150 to get the exact amount of quercetin in milligrams.

Giving your dog foods like spinach, blueberries, and strawberries will provide natural Benadryl dosage for dogs.


Benadryl for dogs alternatives - CBD

CBD (cannabidiol) is a great natural alternative for Benadryl for dogs with skin conditions caused by allergies. Let's get one thing straight first, CBD has no THC (tetrahydrocannabinol) in it nor any psychoactive properties, so your doggo won't get high.

CBD that we use in medicinal purposes is not derived from marijuana but from hemp that possesses health benefits that can help relieve itchy and dry skin caused by allergic reactions. It will also calm your doggo down if it gets super anxious during car rides, fireworks, or separation. It will also be very beneficial for doggos who suffer from cancer, or they experience some pain.

CBD is available in the form of oils, balms, and lotion.

Baking Soda

This might seem weird, but baking soda will immediately calm down red, itchy, and inflamed skin. Just make a paste out of it with a bit of water, place it on the affected area, and sit for a couple of hours before washing it off. In case your dog tends to lick the affected area, you should try making a spray with baking soda and water. Please make sure you shake it well before each use.

If your dog still tries to lick the problematic area, you should opt for a cone of shame to prevent any risk.


Oatmeal also can serve as an excellent alternative for soothing irritated and itchy skin. Like with baking soda, it is the best way to make a paste out of it and massage it onto your pooches skin. Leave it be for approximately 20 minutes and rinse it off with warm water.

If your dog is a big fan of bathing, you can draw a warm oatmeal bath and soak your pup for 20 minutes to relieve the itchy skin.

Apple Cider Vinegar

One more popular holistic alternative that will replace over the counter drugs is apple cider vinegar. It is also beneficial for irritated and itchy skin since it features powerful antibacterial and anti-fungal properties. Make a spray out of it using 50/50 water and apple cider vinegar mix. Use this mix on the affected area, but only in cases where there are no open wounds since this will hurt your pup for sure.

Can I Give My Dog Benadryl Every Day?

Yes, you can give Benadryl to your dog every day, but like I said, already using it too frequently will make your pup resistant to it. I highly recommend using natural alternatives for Benadryl if you want to treat motion sickness, anxiety, nausea, mild skin irritations, and itchiness. In case of some severe health problems, use regular Benadryl in the proper dosage, make sure not to use too much of it, and avoid an overdose.

Can I Give My Pitbull Benadryl?

There's no special rules that adhere to pitbulls regarding Benadryl - same rules mentioned above apply. 

What Can I Give My Dog For Itching?

If your dog has itchy skin, you can reach out for over the counter drugs such as Benadryl, Dramamine, and some other meds based on steroids. But I always prefer to try first with some natural home remedies like aloe vera, coconut oil, apple cider vinegar, oatmeal baths, chamomile, and green tea, or baking soda.

Remember feeding your dogs a well-balanced diet will greatly improve their skin condition and help soothe and heal the irritated skin faster. Avoid using wheat and other gluten-rich ingredients, cut out beef and chicken, and substitute them with fatty fish since omega-3 fatty acids are proven to reduce inflammation.

Before making any significant changes in your dog's diet, consult with your vet.

Wrapping Things Up

can I give my dog benadryl? - final thoughts

Like I already said, Benadryl is safe for dogs if you take care and use the proper dosage. How much Benadryl can I give my dog is a question that differs from dog to dog according to their breed, weight, and current health condition. Although many veterinarians consider Benadryl safe for dogs to treat allergies, anxiety, and motion sickness you, as a pet parent, should always be aware of possible risks and side effects of any med you administer to them.

Never exceed the recommended correct dosage since overdose on Benadryl in dogs can cause severe health issues, and it can even be lethal for dogs. Observe your dog closely after administration, and if you are unsure about should you use this drug or not, reach out for your vet for further instruction.

About the Author

A devoted pet parent to two lovely creatures – Charlie the Cat and Jimmy the Dog – a full-time assistant pet store manager, and an animal shelter volunteer. I've gathered knowledge about pets for almost a decade, and it all started in a small store called Jack's Pets.

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