Benadryl for Dogs: The Pros and Cons

Benadryl for Dogs: The Pros and Cons

  • Kirsten Thornhill - 31.12.2019



Do you take Benadryl for seasonal allergies? Have you given Benadryl to your pup? Most likely. Benadryl is a popular and seasonal medication that helps alleviate and relieve seasonal allergies. 


Benadryl is an antihistamine that blocks histamine (H1) receptors. H1 receptors are commonly present in smooth muscle and amongst your blood vessels. These H1 receptors, histamine receptors, play a leading role in the overall allergic response (commonly referred to as allergies).


Benadryl not only blocks this receptor but also reduces symptoms of these allergic reactions. Benadryl has also been used to provide mild sedation as well as being used to treat motion sickness for dogs. 


What would your veterinarian say about Benadryl? Many veterinarians and experts consider Benadryl to have a large safety margin, but there are still potentials for adverse side effects associated with the drug that paw parents should be aware of.




The active ingredient in Benadryl is diphenhydramine HCl. Diphenhydramine has been categorized as a first-generation antihistamine: it reduces the effects of histamine in your dog’s system. It can enter and cross the blood-brain barrier to address an allergic response. The blood-brain barrier protects the brain from dangerous or harmful foreign substances, like bacteria or foreign viruses for instance. However, this blood-brain barrier does allow some substances, like diphenhydramine, to pass on through.


Because Diphenhydramine is able to cross the blood-brain barrier, this means that it is typically very effective in treating the allergic response. Diphenhydramine’s ability to cross the blood-brain barrier does, unfortunately, lead to increased risks for potential adverse reactions. 




As most dog owners know, because of their own use of Benadryl, the drug is most commonly used to alleviate allergies.


However, what some individuals may not realize is that Benadryl can be used for several other uses.




Let's start with the basics of allergies. When we think about allergies, we typically think about a runny nose, constant sneezing, itchy and irritated eyes, and too many issues.


Unlike us humans, dogs have different symptoms when experience allergies. In most cases, dogs show allergic reactions on their skin’s surface. It is possible that dogs will show signs of allergies that are similar to those you experience yourself, but you’ll want to make sure that your pup doesn’t have a more serious issue at hand.


If your dog is having nasal discharge, coughing, and or inflamed eyes, these can be signs of multiple conditions in dogs, especially respiratory infections. So, it’s important not to automatically assume that your pup’s symptoms are from allergies (they may be simply masking the true root of the problem). 


When all is said and done, your dog may suffer from allergies & your vet may recommend Benadryl to help alleviate your dog’s symptoms. 



    • Seasonal allergies
    • Environmental allergies
    • Food/drink allergies
    • Insect bite allergic reactions


Unfortunately, we aren’t exactly able to communicate with our dogs in a clear way, despite how badly we wish we could. Our dogs can’t let us know when something in the air is bugging them, or if their food has ingredients they don’t like, or if any of this is making them feel funny. We can’t describe to them how badly insect bites feel and ask them to please avoid those fun, innocent-looking bugs are in the grass. 


For this reason, knowing that Benadryl is safe to give to dogs, makes many dog owners feel somewhat at ease if their fun-loving pup is prone to being in grassy, itchy situations. With this being said, we want to emphasize, as in humans, allergies and other various conditions can be mistaken or mistreated for one another. Taking your pup to see the vet will give assurance in determining whether or not your dog has a skin infection/condition or an allergic reaction. 




Many veterinarians and pet owners find Benadryl to be a highly effective antihistamine for mild to moderate allergic reactions. 


However, if your dog is having an acute allergic reaction with difficulty breathing or facial swelling, it is extremely important that you go directly to the vet.


Benadryl is not effective in serious cases of allergies. Seeking medical treatment and intervention in a timely manner is crucial for your dog’s life if he/she is having allergies. 




Benadryl is typically administered in tablet form when prescribed for dogs. However, liquid Benadryl can be mixed what your dog’s food, only if your vet confirms this is safe to do so. Consult with your vet first!


Benadryl dosage is based on your doggo’s body weight. Below, we’ve included a general guide for giving your dog Benadryl. 


For dog owners who want an accurate dose, experts say that 1 milligram (mg) of Benadryl per pound of body weight is the most accurate way to calculate the amount of Benadryl that will be safe, effective, and appropriate for your dog. 



    Dose       Weight of Dog


30 lbs  or less       10 mg per dose

30 - 50 lbs             25 mg per dose

50 lbs or greater    50 mg per dose

You can typically give this medication to your dog is around 2 -3 times per day, at least 8 hours apart between doses. Benadryl takes typically 30 minutes after administration to come into effect. Not all dogs are the same - all dogs respond differently to new medications. Therefore, it is extremely important to talk to your vet about the dose that is ideal and right for your particular doggo.




Benadryl has been deemed safe for dog use when used appropriately, but there are a few things to be aware of as a dog owner. 




Doggos with glaucoma, cardiovascular disease, heart conditions, and high blood pressure should avoid Benadryl, as it can worsen their condition. 



Avoid giving Benadryl if your dog has any or all of the following:

  • Allergic lung diseases
  • Heart failure
  • Angle-closure glaucoma
  • Pregnancy
  • Nursing
  • Hyperthyroidism
  • Seizures


Side effects of Benadryl:


  • Increased heart rate
  • Fast breathing
  • Urinary retention
  • Dry mouth
  • Decreased/increased appetite
  • Vomit
  • Diarrhea




Benadryl has also been known to effectively treat hives in both humans and doggos. In dogs, most of the time, hives are simply due to allergic reactions. 


In humans, hives can be symptoms of several underlying medical conditions, so treating them with Benadryl may work for immediate relief, but not as a long-term treatment and will certainly not cure it.


Pets will hives may look pretty sad and miserable, we want to encourage pet owners not to panic if your pup breaks out in hives. These hives can be treated, typically without any issues or complications. 




One major side effect of diphenhydramine, the leading active ingredient in Benadryl, is drowsiness. If your pup has anxiety, your vet may prescribe Benadryl to help ease symptoms of anxiety and help effectively calm your anxious guy/girl down. 




Pet owners may not know that Benadryl is recommended for dogs who often experience motion sickness in the car.




Mast cells are white blood cells that play a role in allergies. When your dog has mast cell tumors, this leads to mast cell degranulation. This causes a massive histamine release, aka, an allergic reaction. 


If your dog has a mast cell tumor, your vet may recommend Benadryl to alleviate and reduce symptoms from the histamine release from the mast tumor cells. 




When adult heartworms are present, heartworm treatment kills these adult heartworms. The death of these heartworms can trigger and lead to a serious allergic reaction for your pup. If your pet has to undergo heartworm treatment, it is common that your vet may recommend Benadryl to ease the symptoms associated with the heartworm treatment. 




Many veterinarians and pet owners find Benadryl to be a highly effective antihistamine for mild to moderate allergic reactions. 


However, if your dog is having an acute allergic reaction with difficulty breathing or face swelling, it is extremely important that you go directly to the vet.


Benadryl is not effective in serious cases of allergies. Seeking medical treatment and intervention in a timely manner is crucial for your dog’s life if he/she is having allergies.




Benadryl can cause hyperexcitability of your dog’s central nervous system. It is critical to seek proper medical attention if your dog may be experiencing an overdose.


Overdose signs include:


  • Seizures
  • Rapid heart rate
  • Irregular heartbeat
  • Confusion
  • Constipation
  • Muscle tremors




As a pet owner, you got options! Luckily, there are some extremely effective and safe alternatives to Benadryl that may support skin health. Alternatives down below come with virtually no side effects. Peep below!

Coconut Oil  


You can totally give your pup coconut oil to soothe any irritation and even prevent parasites. Key tip - look for coconut oil that is high in lauric acid, this makes the coconut oil more effective. Apply a small amount directly to your dog’s skin or feed it to them. Feed them a small amount (¼ teaspoon for small pups, 1 teaspoon - 1 tablespoon for large pups) 1 - 2 times a day with their meals.


Oatmeal Bath


An oatmeal bath can serve as a soothing home remedy for your pup’s irritated and itchy skin, given that your dog isn’t allergic to oatmeal (which would be horrible, let’s be honest). Step one, mix plain oatmeal with water and apply it to your dog’s irritated skin. Step one in a half, or you can run a bath and add oatmeal directly to the water. Let your pup soak for 10 minutes to put their scratchy, itchy skin at ease. 


CBD Oil Drops


Whether your pup is a small breed, large breed, or something in between, we've got you covered with Pet Hemp CBD. Here, at PETLYcbd, we've crafted some of the most organically grown phytocannabinoid-rich hemp available.  With each bottle containing 30 droppers at specified milligrams per dropper (depending on your dog's size), this natural product supports canine health. 


CBD Oil Dog Treats


You can also use our 2 mg of broad-spectrum hemp CBD. We recommend our PETLYcbd natural beef flavor CBD pet chews. These treats include grain-free, preservative-free, and non-GMO, organically grown hemp that supports healthy skin and a smooth, healthy coat. These scrumptious, chewable treats are definitely a paw favorite. 




We understand how stressful and overwhelming it can be - shuffling through endless lists of medications and conventional drug options, figuring out what’s safe and what isn't, which option has the least amount of side effects, and what has the least potential for adverse reactions. Here, at PETLYcbd, we understand just how difficult it can be ensuring that you're doing all you can to make sure your pup is living their best life. Medications like Benadryl may be “safe” for short-term treatment, yes, but it is comforting to know it’s not your only solution. We encourage our readers to explore all-natural, organic options like CBD.


Your doggo will definitely thank you!


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