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Is Benadryl Safe For Your Furry Friend? What Are The Side-Effects?

If you are a pet parent, you must be aware of the difficulties that a dog goes through when there is an onset of allergies. Especially when you reside in an area where the bloom season means that the air particles are loaded with millions of micro pollens, then your concerns are real because these pollens can lodge themselves in your pet’s airways and make it sneeze, cough and have painful itches.

A lot of us have heard of dogs being administered Benadryl as an anti-histamine to avoid these allergies.

However, Benadryl is largely a medicine used by humans. Is it safe to give to your dog? Let us find out.

Why Is It Used?

Surveys suggest that Benadryl is often prescribed by doctors to dogs that are suffering from the various symptoms of allergies like runny noses, itchy skin, watery eyes and anxiety attacks. There is a particular ingredient in Benadryl that acts as an antihistamine and counters the chemical histamines that cause the allergic reactions in your pet’s system. The name of this ingredient is Diphenhydramine. This particular ingredient is also quite efficient at giving your dog a sleepy and peaceful night.

When Is Benadryl Recommended?

There are a few health conditions in which Benadryl is specifically prescribed and they are listed below.


Your dog could have various symptoms of allergies and they range from itchiness to sneezing, coughing, hives, inflammation, runny nose and eyes to red patchy skin.


Pets are often bitten by insects or smaller animals if they tend to be outdoors for long. If your dog has been bitten and there is visible inflammation, you can use Benadryl to reduce the swelling and the associated discomfort.


Diphenhydramine, the chemical found in Benadryl, is known for its sleep-inducing properties. If your dog often has anxiety attacks and does not sleep well at night, you could give him the prescribed dosage to help him sleep better.

Miscellaneous Reasons

There are other situations in which a doctor might recommend the usage of Benadryl. If your dog has motion sickness and still needs to travel for unavoidable reasons, a dose of Benadryl can alleviate nausea and help him sleep through the journey. Benadryl is also used to curb and treat a tumour related conditions.

Can You Buy Benadryl Over-The-Counter?

While Benadryl does have a number of benefits, there are a few dos and don’ts that come along with this over-the-counter medication.

What To Do

  • Always test half the amount of drug to check for reactions. Wait for a couple of hours and see whether your dog takes it without any side-effect.
  • Feed your dog well before giving Benadryl because it often has side-effects like nausea or loss of appetite. If your dog is full, the impact is likely to be reduced.
  • If your dog is not fond of chewing tablets, break it up and add to his meals.
  • Always consult a vet before giving Benadryl to your dog.

What Not To Do

  • Never give Benadryl to puppies without consulting a vet. Puppies are ten times more likely to fall sick if their bodies cannot handle the medication.
  • Do not give liquid Benadryl to your pet because this form of medication tends to have high concentrations of alcohol that could be unsafe for your pet.
  • Never exceed the dose recommended by the doctor. It could be fatal for your dog.

Side Effects Of Benadryl

Every drug has a side-effect and while some have mild to moderate effects, some others bring along a lot of trouble if the dosage is not followed.

Benadryl is an in-between drug.

You should always check with the vet before administering Benadryl. Listed below are the conditions that you must address immediately if your dog is put on Benadryl.

  • If your dog is pregnant
  • Is prone to seizures
  • Has had heart failure
  • Has a lung disease
  • Has a history of glaucoma
  • Hypertrophy of the prostrate

The side-effects of Benadryl could be broadly classified into two parts. Let us take a look at the common side-effects and later at the rare side effects of Benadryl.

Common Side-Effects

  • Urine retention
  • Excessive drowsiness
  • Dry mouth
  • Excessive salivation
  • Heavy breathing
  • Rapid heart rate

Rare Side-Effects

  • Diarrhea
  • Excessive nausea
  • Frequent vomiting
  • Reduced appetite
  • Huge appetite

Signs Of Benadryl Overdose

Benadryl can be dangerous when the dosage is exceeded. It could affect the central nervous system of your dog and could be a fatal condition. The symptoms of an overdose include:

  • Seizures
  • Rapid heart rate
  • Dilation of pupils
  • Irritability

Keep a close on your dog in the first 4 to 5 hours of giving Benadryl because this is when the first signs and symptoms start manifesting.

Recommended Dosage (Check With Your Vet!)

The size of the dog decided the dosage of Benadryl. Your vet will be the best person to make the recommendation. Here is a table for your reference.

Size of the dogDosage of Benadryl
Lighter than 30 lbs10 mg
Between 30 to 50 lbs25 mg
Heavier than 50 lbs50 mg

Every dosage of Benadryl must be 8 hours apart. Ideally, you are supposed to give three doses of Benadryl to your dog in a span of 24 hours.

Final Thoughts – Always Check With Your Vet!

Considering the fact that Benadryl is a rather controversial medicine, the best way to administer it would be by consulting your veterinarian and using as per prescription.

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