Benadryl for Dogs: When Can You Use it and Why? Will Benadryl Make My Dog Sleepy?

Does your dog have a problem with food, skin or flea allergies?

Is he itching, biting or clawing at his skin all of the time?

Maybe your dog has a problem with constant anxiety or restlessness?

If your answer was yes to any of the questions above, Benadryl for dogs could be an absolutely fantastic solution to your problems!

That being said, there are many things a responsible pet owner who truly cares about the well being and comfort of their dog should know about Benadryl before simply offering is on a whim.

Be the loving, caring and educated pet owner we know you are; find out below exactly what you are giving your pet, when to give it, and how it works!

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1. Quick Links to Our Picks

2. What is Benadryl

3. How Does Benadryl Work on Dogs?

4. How Does Benadryl Affect Dogs, and What is it Used for?

5. What Are the Side Effect of Benadryl?

6. Benadryl Dosage for Dogs. Symptoms of an Overdose.

7. Benadryl for Puppies

8. How Long Does Benadryl Last in Dogs?

9. 8 in 1 Excel Allergy Relief, Antihistamine

10. Questions & Answers

11. Conclusion

What is Benadryl for Dogs

Benadryl for dogs is a popular over-the-counter medication, but the main active ingredient is called Diphenhydramine.

Diphenhydramine for dogs is an antihistamine, often used to help relieve symptoms of allergies, hay fever, and the common cold by blocking histamines the body creates during allergic reactions.

It also helps treat nausea, vomiting, and dizziness, as well as help relaxation.

  • Sometimes, manufacturers will combine other drugs with Diphenhydramine in their Benadryl tablets; not all Benadryl is the exact same.
  • It’s important to make sure there is only Diphenhydramine in the tablets when medicating!

In general, the medication was designed for use with humans (but can be given to dogs), helping treat the list of symptoms below:

  • Rash
  • Itching
  • Watery eyes
  • Itchy eyes/nose/throat
  • Cough
  • Runny nose
  • Sneezing
  • Symptoms caused by motion sickness
  • Helps relax/ fall asleep (we write an article on how to help with anxiety)

Diphenhydramine for dogs is considered a first-generation ethanolamine-derivative antihistamine, meaning it can cross the ‘blood-brain barrier’ where others can’t.

This ability helps make Diphenhydramine pretty effective, but can also increase the risk of side effects over other medications that can’t cross the ‘blood-brain barrier’.

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How Does Benadryl Work on Dogs?

As a receptor antagonist, Diphenhydramine for dogs works by blocking the histamine receiving receptors in the body (either humans or dogs).

In turn, this helps with many of the symptoms associated with allergies, including:

  • Itching
  • Sneezing
  • Hives

The body still receives these histamines that are released during an allergic reaction, but the receptors are blocked from registering them.

It can be compared to attempting to leave a phone message on a mailbox that is full.

The cell phone answering machine still works, but the carrier automatically won’t accept it!

Variants of Benadryl for Dogs

  • Itch-Cooling Gel – Comprise camphor as one of its components, a substance that is poisonous to dogs.
  • Time-Release Capsules – A dog’s alimentary system is unable to completely digest capsules when gulped whole.
  • Liquid Benadryl – Generally keep high alcohol substance which is unsafe for dogs.

How Does Benadryl Affect Dogs, and What is it Used for?

Though Benadryl can be used with dogs, it might work to treat slightly different symptoms because dogs tend to react to allergies differently than humans.

Usually (not always) dogs show reactions through their skin via itching, redness, swelling, etc.

Humans, on the other hand, might have these symptoms in addition to dangerous swelling of the face and throat.

Benadryl is often used to treat dogs for:

  • Itching
  • Hives
  • Swelling and inflammation
  • Redness
  • Runny nose and eyes
  • Coughing
  • Sneezing
  • Anaphylactic reaction

Dogs suffering from seasonal allergies, food allergies, and mild allergic reactions to bites (such as flea bites) usually respond well to Benadryl.

It’s most commonly used to treat skin allergies.

One of the side effects of giving Benadryl for dogs is drowsiness, which helps with anxious dogs.

For example, owners might give their dogs Benadryl to help with travel or car anxiety, which is pretty common.

It can even help relieve motion sickness in dogs with that problem.

When Benadryl for dogs isn’t Enough

Though dogs suffering from allergic reactions usually don’t swell in the neck or face, especially not to the extreme that it blocks their airway, this does happen.

Benadryl isn’t going to help much if your dog’s throat is beginning to close, even if he is able to swallow it.

If this happens, it’s vitally important to get to a veterinarian as soon as possible so they can administer an intravenous injection in order to relieve the swelling!

What Are the Side Effects of Benadryl for Dogs?

Like most drugs, Benadryl for dogs isn’t 100% safe 100% of the time; although rare, there are side effects.

Just like people check with their doctors before starting a new medication, you should always check with your veterinarian to make sure there are no possible complications with other drugs your dog might be taking, or to make sure it won’t worsen a pre-existing condition.

Do Your Dog Has Following Conditions? Talk With Vet!

If your dog has any of the following conditions, make sure you talk with your veterinarian before using Benadryl for dogs:

  • Angle-closure glaucoma
  • Severe heart failure
  • Prostatic hypertrophy
  • Hyperthyroidism
  • Bladder obstruction
  • Seizure disorders
  • Liver disease
  • Kidney disease
  • Hypertension
  • Allergic lung disease
  • Pregnancy

You must avoid Benadryl with the cetirizine to give dogs with kidney or liver disease.

Common Side Effects

Common side effects associated with this allergy medicine and dogs (although rare in general) are:

  • Sedation
  • Dry mouth
  • Decrease in urination
  • Hypersalivation
  • Increased heart rate
  • Rapid breathing
  • Diarrhea
  • Vomiting
  • Loss of appetite
  • Sluggishness
  • Sleepiness
  • Allergic reaction

If your dog has an allergic reaction immediately take care from veterinary supervision.

Benadryl for dogs may react with these drugs

  • Selegiline
  • Depressants of the central nervous system
  • Furazolidone
  • Epinephrine
  • Amitraz
  • Warfarin sodium
  • Selegiline
  • Heparin sodium or calcium

Benadryl Dosage for Dogs. Symptoms of an Overdose.

Benadryl Dosage for Dogs

Benadryl Dosage for Dogs

The usual dosage is 1 mg per pound of bodyweight, given 2-3 times a day. You can see the dosage chart above.

If you’re wondering whether or not your dog can overdose, the answer is certainly yes.

Miss using more than one type of antihistamine at a time for this could conduct to overdose.

Overdoses can be very dangerous to life-threatening, which is one reason why it is so very important to contact your veterinarian before giving it out to your dog!

If/when your dog overdoses on tablets, symptoms will include a hyper-excitability of the dog’s central nervous system and can be fatal if not attended to a veterinarian immediately.

The risk of overdose increases when benadryl tablet or liquid or other antihistamine preparations are also given simultaneously.

Common symptoms of an overdose

  • Breathing seizures
  • Rapid heart rate
  • Extreme fatigue
  • Agitation
  • Rave
  • Constipation
  • Hyperthermia
  • High blood pressure
  • Muscle tremors

Since Benadryl for dogs is supposed to give a calming effect, the agitation/increased anxiety will often be a clear indication there is a problem.

It’s also possible that some dogs (although rare) may be allergic to the medication.

Thankfully, you now have a better idea of how an allergy works and how the body reacts to it!

Since Benadryl for dogs is used to treat allergies, this is certainly not a good thing; you should again consult your vet as soon as possible!

Benadryl for Puppies

Like young human children, a puppy’s immune system is weaker than adult dogs.

Now you know that you can give an adult dog Benadryl, but can you give it to a puppy also?

The answer to that question is yes – you can give Benadryl to puppies in some cases, but puppies younger than 4 months might have trouble handling the powerful antihistamine (again, it’s important to contact your veterinarian first).

That being said, due to their size, it is very easy to overdose, and an overdose can be worse for a 5-pound puppy than a fully grown adult.

Questions to ask yourself before giving these tablets to a small dog or puppy

  • The recommended dosage is 1 mg per pound of body weight.
  • Chewable adult tablets normally come in doses of 25 mg or sometimes (but less often) 12.5 mg.
  • Children’s Benadryl usually contains 12.5 mg of Diphenhydramine

If you’ve just given a 10, or even 15-pound puppy a full 25 mg. capsule/tablet, you’ve overdosed your dog.

If you’ve given a 5-pound puppy a full dose, and continue to offer the same dose as recommended for an adult dog or human, you might have just made the problem much worse.

Even if you chop the tablet in half, how can you be sure what the new dosage is?

You can’t be sure.

In the end, it is safer to avoid administering the remedy to very young puppies, which is probably what your veterinarian will tell you.

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How Long Does Benadryl Last in Dogs?

In dogs, Benadryl usually lasts 8-12 hours.

The keyword is usually!

This will depend on things like the amount given, size of the dog, how much food you gave along with the tablet, energy levels/ age of the dog, etc.

  • Normally 8-12 hours

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Questions & Answers

1. Can you give a dog Benadryl?

Yes! Dogs can take it, for much the same purposes as humans.

On the other hand, the dosage is different for dogs, or even a dog the same size.

Even if you think you know how much to give, it’s important to ask your veterinarian what the exact dosage for your dog should be.

Certain medical conditions contraindicate the use of benadryl, like high blood pressure or cardiovascular disease.

For a long time, and even to this day, countless pets suffer from allergies that could easily be treated with something as simple as Benadryl.


2. How much Benadryl can I give my dog?

Before anything else, this is a question for your veterinarian, just in case there is a complication with your particular pet or breed.

That being said, the usual dose is 1 mg per pound of body weight, given 2-3 times a day.

3. How often can I give my dog Benadryl?

Again, the normal dose for medicine given to a dog is 1 mg. per pound of body weight, given 2-3 times daily.

Just like most things, too much isn’t good; re-administering benadryl over and over if you don’t see an improvement right away is certainly a bad thing.

If you aren’t sure how much to give or if you’ve given too much to your dog, your veterinarian is only a phone call away!

Sometimes all it takes is one dose.

4. How much Benadryl for a 10-pound dog? For a 15 pound dog?

The standard dosage for dogs is 1 mg. per pound of body weight, given 2-3 times daily as needed.

For a 10 pound dog, that would be 10 mgs. and 15 mgs. for a 15 pound dog.

That being said, it is always important to consult your veterinarian before offering any drug to your pet, if only to make sure there would be no complications!

5. Is it safe to give Benadryl for dogs?

In most cases, yes.

Although sometimes other drugs besides Diphenhydramine (which is what you are focusing on) are contained within store bought these tablets.

You want to make sure this isn’t the case for your dog!

6. How much children’s Benadryl can I give my dog?

You might have a problem getting your dog to drink the liquid form of Children’s Benadryl, as they probably won’t like the taste.

That being said, this completely depends on the dosage for both liquid and solid forms.

On the benadryl homepage, the children’s version of the drug is listed as coming in quantities of Diphenhydramine HCl 12.5 mg.

Remember, the standard dose is one mg. per pound of body weight, 2-3 times daily.

So, the answer to this question will depend on the size of the dog.

7. Will Benadryl make my dog sleepy or tired?

Drowsiness is one of the side effects of Diphenhydramine (the main ingredient, and hopefully only ingredient, in Benadryl), so it will probably make your dog sleepy.

Of course, this isn’t 100% guaranteed to always make your dog tired; he might not become sleepy at all!

It also depends upon the age and size of your dog, and basic energy levels.

If your dog is eating a complete meal along with the benadryl, it will likely digest slower and may not make him tired.

If you want to make your dog sleepy, then you need to read this article about sleeping pills.

8. What are the doses of Benadryl for dogs, or what doses does it normally come in?

Adult Tablets: 25 milligrams
Adult Extra Strength Tablets: 50 milligrams
Children’s Tablets: 12.5 milligrams

9. How long does it take for Benadryl to work for a dog?

Usually, it takes about 30 minutes for Benadryl to start working. If it will not help in this time, you need to take your pet to Vet.

If you do not want the dog to be scared of fireworks, then you need to take pills 30 minutes before the start.

10. How much Benadryl for a dog to go to sleep? Does Benadryl make dogs sleepy?

Drowsiness is one of the side effects of benadryl. But we advise you to read the article about sleeping pills before giving benadryl.

11. How often can I give my dog Benadryl for allergies, itching or hives?

It is necessary to stick to the daily dose given to your pet.

12. How much Benadryl for a small dog?

It will depend on the dog’s weight and daily dosage.

13. Can you give a puppy Benadryl to sleep?

You can give benadryl for puppies in some cases, but it is very easy to overdose small puppy.

So it is safer to avoid administering the remedy to very young puppies.

14. How much liquid Benadryl to give a dog?

Liquid benadryl contains high alcohol content which is risky to dogs.

15. Is it ok to use Benadryl spray on a dog? Why or why not?

Dogs incline to lick off the medicament before it can take effect.

It is a good idea to put an E-collar on your dog or involve in some activism to keep him from licking the treated area.

Video: Hives, Allergies, Benadryl for Dogs

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In the end, Benadryl for dogs can be just as great for dogs as humans, treating things like:

  • Allergic reactions
  • Anxiety (ex.- travel or company)
  • Restlessness

However, like any drug, pet parents need to be cautious.

No matter the size of the dog or how much you think you know, you probably aren’t a doctor (let alone a veterinarian).

Call your vet first; it’s free, and won’t take up very much of your time at all!

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