Benadryl For Dogs – Meaning, Dosage, Uses and Side Effects

benadryl for dogs

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Most pet owners would admit they have at one point or another felt the temptation to reach out to their medicine pack to treat their dogs without any supervision from a vet and this can be very dangerous. In this article, we would be giving you everything you need to know about benadryl for dogs.

Just like how humans react differently to medications, dogs are no exception and that is why a vet would always caution a pet owner to not make independent decisions when it comes to their pets medications. Regardless, there are some human medications that are safe to use for dogs as long as they are used in the right way.

Veterinarians make use of benadryl for dogs on a regular basis in treating dog allergies and sometimes travel anxiety as well as motion sickness in some cases. Even though you need to consult your vet before giving your dog medications meant for humans here are still a few things you need to know about the use of benadryl for dogs.

What is Benadryl?

Benadryl is also the brand name for an active ingredient called diphenhydramine HCL. Diphenhydraime is also considered as part of the first generation ethanolamine-derivative antihistamine which is also a scientific way of classifying antihistamines that are capable of crossing the blood brain barrier from the ones that cannot. Benadryl is also an over-the-counter antihistamine that is used to calm allergic reactions to environmental allergens, insects stings and also bites as well as some vaccine reactions.

This drug is a human drug and it is not approved for dogs and other animals by the FDA but you can also give it to your dog only with approval from your vet. Benadryl is not the only drug that can be used to treat allergies. There are other brands that make drugs that you can use to treat allergies and there are also some drugs under the Benadryl brand you must also avoid if you have no knowledge about it.

Before giving a medication to your dog, you should always read the ingredients of the medication. Diphenhydraime is the ingredient active in Benadryl that is considered safe for canines. You could also see certizine as well and it is safe for dogs as well but while it may be safe, there is really no need to expose your dog to it if it is not necessary.

Products that contain ingredients like acetaminophen and pseudophedrine should not be used for your dogs because they are not safe for them as they are very toxic to canines. Benadryl can also be used for other animals like cats and it is used by many vets across the United States Of America.

How does Benadyrl work?

Diphenhydramine is considered to be a receptor antagonist which also means that the drug works by blocking the receptors that receives histamines in the body. This process helps relieves many of the symptoms associated with certain allergies like itching, sneezing and many more.

Mind you, you should not ignore the fact that the body still produces histamines but the receptor antagonist will block the receptors from registering the histamines. An example to better understand this process is taking a basket of food for example, imagine a full basket of food that more food is being added, the excess food just falls out because there is no room for it anymore.

When to ask your vet about benadyrl for your dog

Before going ahead to get the Benadryl, first you should consult your vet about the symptoms your dog is exhibiting. Some allergy symptoms like itching and red eyes can also be signs of a very serious condition. Giving your dog Benadryl in some cases can worsen the dogs condition especially in some cases like glaucoma.

As much as red and goopy eyes can be a symptom of allergies, it would also be a sign of an eye disease like glaucoma mentioned earlier and Benadryl cannot help treat the disease. Also when your dog is itching it could signify an allergy and it could also be because of a skin condition. Make sure you always consult your vet before making any moves on medicating your dog so as to make sure you are doing what is best for your dog.

In some cases your vet might recommend you bring your dog in for checkup from time to time and if you choose to go against the vets advice and not bring your dog in or if you try to administer Benadryl to your dog without the vets consent just make sure you are keeping a close eye on your dog. Make sure you also call your vet if your dog’s condition worsens.


The ideal dosage of the Benadryl for dogs is 1mg for every pound of body weight of the dog. However, before you even administer any drug to your dog make sure you are consulting your vet first as so many factors can change the dosage recommendation for your dog.

The average dosage a tablet contains is about 25mg so by calculations a 25 pound dog would only need one tablet of Benadryl. But any precaution you should take is also by checking the dosage on the package because not every product would have the same dosage on a tablet.

Make sure you are using the tablets for your dog and not the liquid form of it because the liquid form may contain alcohol and alcohol is not good for your dog.

When you want to give a smaller dog the Benadryl make sure you use the children’s formula as it has less of the active ingredient and it is always easy to measure. Also, the children’s formula of the liquid Benadryl has no alcohol.

The Benadryl also has a tropical form that can help with your dog’s itching. For this you should also consult your vet before using any cream or gel on your dog.

Ideally, you can administer the Benadryl to your dog every 8 to 12 hours so that is about 2 to 3 times every day. Also, watch out, if you use the product frequently your dog’s body will build resistance to it and it would start to lose effectiveness overtime.

In most cases, the best option is to use to use the drug before your dog is exposed to allergens. You should also follow your vets guidelines and if they recommend a regimen make sure you stick to it for the duration proposed by your vet even if the symptoms go away.

Initially, Benadryl takes about 30 minutes before it starts working so when you want to use it for your dog, plan accordingly especially when you want to use it to treat anxiety or mild motion sickness. For dogs that have very serious allergies or even conditions that would require them having daily doses of Benadryl, make sure you consult your vet about the appropriate dosage as it is subject to change.

If your dog is pregnant also consult your vet before giving Benadryl to them as they are not recommended for use in these animals.


When you give Benadryl to a dog without prescription from a vet it is possible for your dog to overdose on them. Signs of an overdose can include hyper-excitability of the central nervous system (CNS) and it can be very serious. Other symptoms of overdose include:

Rapid heartbeat
Dilated Pupils

Once you notice the symptoms of a Benadryl overdose make sure you contact a vet or an emergency vet hospital immediately.
Some dogs can even develop an allergic reaction to Benadryl. If you notice your dog is having an allergic reaction to Benadryl make sure you consult your vet immediately. Even though Benadryl is used in treating allergies in dogs, keep an eye on them after you administer the first dose to make sure their allergy symptoms do not worsen.


Benadryl has quite a number of uses. They are used to reduce many of the symptoms of allergies in dogs. These allergic reactions include inflammation, watery eyes, headaches, itching and sneezing and many more. These allergic reactions can come from many sources like environmental or seasonal allergens as well as stings and bites from some insects and also medications.

Symptoms of allergies Benadryl help reduce includes; itching, hives, swelling as well as inflammation, Redness, Runny nose and eyes, Coughing, Sneezing, Anaphylactic reaction and many more.

Since the active ingredient in Benadryl which Is Diphenhydraime is also similar to the ingredient in Daramine, it can be used to treat nausea as well as travel sickness. In most cases it is recommended before flights and even car rides to reduce the symptoms in them.

With the sedative properties present in Benadryl, it makes it an effective treatment for anxiety. Some pet owners give Benadryl to their dogs during high stress situations or activities that might induce an anxiety attack. Insomnia can also be tackled with Benadryl as it often makes the user drowsy and end up falling asleep.

Vets prescribe Benadryl for dogs that have mast cell tumors to help them mitigate the effects of the massive histamine release caused by mast cell degranulation. Benadryl can also be used as an adjunct therapy for some other conditions. Vets sometimes prescribe diphenhydramine when treating heartworms as it would help in preventing allergic reactions associated with heartworm treatment therapy.

Adding Benadryl to your pet kit is an excellent addition. If you do not have a pet emergency kit or a pet travel kit you should consider getting one today.

Side Effects

There are several side effects associated with the use of Benadryl for dogs and all dog owners should be aware of. Just as people check with their doctors before using new drugs, you should also check with your vet before administering Benadryl to your dog. This is important in order to see if it has any potential drug interactions with the other medications your dog takes as it could worsen a pre-existing condition.

If your dog has any of the conditions listed below, make sure you only use Benadryl after consulting your vet:

Angle Closure
Severe heart failure
Prostatic hypertrophy
Bladder neck obstruction
Seizure disorders
Allergic lung disease

Some common side effects of using Benadryl include:

Dry mouth
Urinary retention
Increased heart rate
Rapid breathing

Rare side effects include:

Decreased appetite
Increased appetite

When your dog uses Benadryl you should start to see the side effects under 4 hours of administration so keep a close eye on your dog during this period.
If your dog is finding it hard to take Benadryl or you want to avoid some side effects, you can consult your vet for alternative medications and you can also try to find a natural approach to fight the symptoms of allergies.

Is it safe for your Dog?

Benadryl is relatively safe and it is a very effective medication for dogs as long as they are used according to the instructions given by a vet.
Same way you do with any new medication, always keep an eye on your dog after administering the drug to them to make sure your dog does not suffer from the side effects. If you need more information on the Benadryl drug you should not hesitate in contacting your vet to find out more about the drug before administering them to your dog.

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