Benadryl for Dogs – Can you Give it? Is it Safe? What Dosage?

Benadryl for Dogs – Can you Give it? Is it Safe? What Dosage?

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Benadryl for dogs written beside a puppy sneezing over a flower

Photo Credit: © / Yarvet


Most people have heard of and have probably taken Benadryl before. It’s a great way to treat a range of human conditions including hay fever, motion sickness and allergies, but – is Benadryl safe for dogs?

If you take your dog to a vet with a condition such as swelling or itching, it’s common for them to recommend giving Benadryl to your pet to help them feel more comfortable.

While it’s always important to listen to your vet and realize that they really do know best, this recommendation for human medication does still leave many dog owners wondering how safe it is to give their pet medicine designed for human consumption.

This article has been created to help you understand what this drug is designed to do, and whether or not it is an effective and safe medicine for dogs.

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What is Benadryl?

Benadryl is an antihistamine which, in humans, is used to help get rid of a wide range of complaints. The name of the drug used in Benadryl is Diphenhydramine, and there are quite a few other brands that also use this drug, including Nytol, Panadol and Benylin.

There’s an enormous range of Benadryl products available from pharmacies, but most forms of the antihistamine also contain the active ingredient Cetirizine (another form of antihistamine), and some also contain Acetaminophen and Pseudoephedrine.

These last two ingredients, Acetaminophen and Pseudoephedrine, are not safe for dogs!

Because of the availability of different products from the Benadryl brand, if your vet recommends you give it to your dog, remember to ask which form you should be giving them. Also, make sure you read the labels of the products carefully before buying.

We will cover pill and liquid forms later in the article.


What is Benadryl For? What Can it treat?

Because it is an antihistamine, most people take it because of allergies such as hay fever, or to minimize irritation caused by allergy to pets, etc.

There are, though, a whole host of complaints tackled by this drug that most people are less aware of, including:

  • Swelling
  • Vomiting
  • Hives
  • Hyperactivity
  • Travel sickness
  • Insomnia
  • Anxiety and stress

How Does Benadryl Work?

When we are affected by any allergy or inflammation, our body’s natural defense is to release a chemical called Histamine.

While this chemical is designed to help us recover from the original problem, unfortunately, it does cause a host of issues itself for most people.

Swelling, itchiness, increased heart rate and even increased stomach acid secretion are all reactions to the natural chemical Histamine.

When Histamine releases into our bodies, it can attach itself to 2 different types of receptors – H1 or H2.

If it reaches the H1 receptors, you might experience symptoms like itching, swelling or difficulty breathing.

H2 receptors cause a very different reaction, with symptoms being linked to heart rate and acid secretions in the stomach increasing.

Although there are huge differences between humans and our canine friends, dogs also have H1 and H2 receptors in their body, that respond in very similar ways to the ones found in people.

To help combat the unwanted symptoms caused by our production of Histamine, many people opt to take an Antihistamine drug, which helps block the actions of the Histamine chemical and relieves us of the symptoms.

This is the same reason dogs are prescribed the drug – to help relieve reactionary symptoms to Histamine.

There are several types of antihistamine drugs, designed to tackle the varied symptoms people face. Benadryl is a brand of Diphenhydramine, which is excellent for reducing problems like itchiness and swelling caused by the H1 receptors.

Benadryl is designed to counteract the problems caused by H1 receptors only, so this drug is not useful for tackling increased heart rate or issues with stomach acid.


Can I Give My Dog Benadryl? Is Benadryl Safe for Dogs?

Vets recommend Benadryl for dogs on a fairly regular basis, so the very broad answer to this question is, yes – in SOME situations, Benadryl is safe to give to dogs.

There are, though, a lot of things you need to check carefully before you go ahead and administer this drug to your pet.

The most important thing to look for is that the particular Benadryl product you have only contains Diphenhydramine.

Cetirizine is an active ingredient in some Benadryl products that can be used for dogs in specific circumstances, but it won’t treat the issues present if your vet has recommended Benadryl.

So steer clear of any products also containing Cetirizine, there’s no need to expose your dog to unnecessary drugs that won’t help them!

Acetaminophen and Pseudoephedrine are also found in some Benadryl products, and while these are a great addition for humans, they are not safe for dogs. If given to dogs, these drugs are considered to be toxins.

The most common problems caused by these two additional drugs are liver damage, and increased heart rate and blood pressure. So just be very careful to look at the ingredients in the product you are hoping to buy.

Even if you’re happy that you have the right product to give to your pet, you simply must still speak to your vet before ever administering it.

There are circumstances where this drug would not be recommended, so get a professional opinion before ever giving it a try.

Can you Give Dogs Benadryl Made for Human Consumption?

There are currently no products of this nature made specifically for dogs, so if your vet does recommend it, the medication made for humans is the only available ‘over the counter’ option.

Currently, the FDA have not approved the use of Benadryl for dogs. However, it is commonly recommended by vets because of its ability to help relieve a range of issues with very few significant side effects.

Make sure you only administer the type of product advised by your vet – the time-release capsules, for example, are a very popular form of the medication for humans, but for dogs they can because a health risk.

If you do give your dog a capsule, they’re likely to receive a dose that’s too high if they chew it, and if swallowed whole, it’s unlikely it will be properly digested which could result in another trip to the vet!

What Specific Things Can Benadryl Treat in Dogs?

Food Allergies

Always check with your vet that any allergies aren’t causing your dog more serious issues, but if this isn’t the case, Benadryl is commonly recommended for this reason.

Bee Stings and Insect Bites

If your dog is not having a severe reaction to a sting or bite, Benadryl can be used to help relieve the irritation caused by common critters.


Benadryl won’t get rid of hives quicker than they would normally disappear on their own, but the drug can make your dog much more comfortable while hives are present.

Reactions to Vaccinations

Some vets recommend giving a dose of Benadryl before arriving for vaccinations to help prevent the onset of any side effects or discomfort caused by the injection.

Calming During Thunderstorms and Fireworks

The drug has a calming effect on dogs and will often make them sleepy and sedated, so it can be useful if your dog finds occasions like storms or fireworks stressful.

If you know there’s an occasion like this coming up, speak to your vet, and stock up on the medication in advance to help keep your dog calm and settled!

Motion Sickness

Because of the effects on the brain and nervous system, this drug is commonly recommended to combat motion sickness.

Benadryl takes about 30 minutes to take effect, so if traveling is an issue, remember to administer the dose half an hour before setting off.

Before Flying

Being helpful for both motion sickness and calming dogs makes Benadryl good medicine to administer before flying to help them pass the time quickly and calmly.

Benadryl Dosage for Dogs – How Much Should You Give a Dog?

Before using any dosage guidelines, make sure you check with your vet, as there is a range of circumstances that might change the amount you should administer.

For a healthy dog, you should weigh them, and per 1 pound of body weight, you should administer 1mg of Benadryl (referring to the products only containing diphenhydramine).

The average size of a Benadryl tablet is 25mg, so if you have a 25-pound dog, you should give them 1 tablet.

In rare occasions such as in response to a snake bite, a single dose may need to be doubled to help make your dog comfortable.

Obviously, if you think your dog has been bitten by a snake, emergency veterinary advice is required.

How Often Can You Give a Dog Benadryl?

The recommended dosage for dogs is the correct amount administered 2 or 3 times per day, with a gap of 8 to 12 hours between doses.

Benadryl should not be given to your pet more than 3 times in any 1 day.

If your vet has recommended giving your dog the drug for a set number of days, make sure you complete the course suggested and don’t stop giving it if your pet starts to seem better.

It may be that the antihistamine is just making them more comfortable and able to cope better with their original symptoms.

If you use Benadryl for dogs on a long term basis, be aware that the effectiveness might start to lessen over time.

If your dog has a condition that needs antihistamines to treat them over a longer period of time, ask your vet for other antihistamine products that you can ‘swap in’ to give them a break from the Benadryl.

Benadryl for Dogs Side Effects

As with any medication, there is a range of side effects that may affect your dog.

Every animal (and human) can respond to drugs differently, so your pet may experience none, some or all of these symptoms:

  • Sleepiness / sedation
  • Lack of interest in food
  • Diarrhoea
  • Sickness
  • Producing less urine than usual
  • Dry mouth

If your dog seems to be having a strong reaction to Benadryl, it may be that they’re very sensitive to it, so speak to your vet again for recommendations of different forms of medication to try.

What Dogs Should NOT be Given Benadryl?

If your dog has any existing disorders or is already taking medication, it may not be recommended for them to take Benadryl.

You shouldn’t administer the drug to your dog if they have any of the following conditions, or have suffered from them in the past:

  • Lung disease
  • Heart disease
  • Glaucoma
  • High blood pressure
  • Enlarged prostate
  • Known sensitivity to diphenhydramine

Pregnancy is also something to consider – the complications caused by needing medication during pregnancy are very similar to those we see in humans!

In general, medication that’s not essential should be avoided to try to keep the unborn puppies as healthy as possible during gestation.

It is not recommended that you administer Benadryl to a pregnant dog, but depending on the individual circumstances, your vet may decide that the need outweighs the risks.

Just make sure you’re very clear in your consultation that your dog is, or may be pregnant if this is the case.

Can You Give A Dog Liquid Benadryl?

Benadryl produce a liquid form of the medicine, and the one specifically designed for children can also be given to dogs as it is alcohol free.

If you decide to use the liquid form, do make sure you work out the correct dosage.

5ml of liquid Benadryl medication should contain 12.5mg of diphenhydramine, and the dosage should be worked out at 0.4ml of medicine per pound of your dog’s weight.

Can You Give A Dog Benadryl Pills?

It is safe to give your dog Benadryl in the form of a pill, as long as it is not the slow-release capsule form.

Check the label carefully to make sure you have selected the right product from the Benadryl range.

How to Give Your Dog Benadryl

If you opt for Benadryl in a pill form, the easiest way to get your dog to swallow them is by hiding it in their food. Most dogs will swallow tablets like this without any issues.

If your dog is more particular and notices you’re trying to sneak something into their dinner, you may need to try a tastier treat to hide it in!

Give them their favorite food, making sure they eat some of the non-medicated portion first, so they don’t realize something is different.

You can also play with your dog and get them to catch a treat if you’re struggling to get them to take pills.

If you can hide their tablet in something tasty that you can throw, just give them a few treats to catch, and sneak the medication into one of the chunks.

If you’re opting for the liquid form rather than pills, the easiest and most accurate way to administer it to your dog is by using a syringe.

It’s very easy to measure out the correct dosage using this method, and most dogs are happy to take the fluid this way.

If you have issues getting your dog to take medication from a syringe, try training them to take water from one first so they get used to the process and sensation of it being squirted into their mouths.

Once they are trained, if you do need to administer medication, they shouldn’t notice the change from water to medicine enough for it to bother them.

Can a Dog Overdose on Benadryl? What to Look for, What to Do?

It is possible for dogs to overdose on Benadryl, and if they do, the consequences can be severe.

If you think your dog may have overdosed on the drug, contact your vet immediately to seek further advice.

If you can get your dog to a professional quickly after a possible overdose, it’s likely they will be able to recover. Cases have been reported of dogs surviving a dosage 16 times higher than recommended with immediate hospital treatment.

Common symptoms that your dog may have received too much of the drug are:

  • Difficulty breathing
  • Fast or irregular heartbeat
  • Tremoring muscles / muscle spasms
  • High temperature
  • Extreme fatigue

A less common side effect of overdosing on this drug is also high blood pressure, which may lead to seizures and other more serious issues.


If you feel your dog may benefit from taking Benadryl, the most important thing to remember is to speak to your vet first. Discuss their symptoms and medical history to discover whether this medication is best.

Don’t make this decision yourself; it must be the advice and decision of your vet!

If you’re unsure about the dosage to give your dog, your vet will easily be able to advise you. They can give you an up to date weight for your pet, and tell you what that translates to in mg or ml of the medication.

Under the direction of a vet, Benadryl is generally a very safe drug to give to dogs, and can offer relief for a huge range of symptoms.

Serious side effects are extremely rare, and usually easy to treat, so just monitor your dog carefully if you’re administering the drug for the first time.

With Benadryl only taking 30 minutes to take effect, you should see your dog settle down and become less concerned with their symptoms relatively quickly, so you can relax knowing they’re as comfortable as possible.



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