How Much Benadryl Should You Give Your Dog?

Introduction: Is It Safe to Use Human Medicines on My Dog?

The very idea of using a medicine that is intended for humans on a dog might seem strange. In most cases, it’s not a good idea to share medicines with your pets. Aside from a few broad similarities, their bodies do not work in the way that our bodies do.

However, dogs are not all that different from humans. We are both mammals, we are both omnivores, and we even have most of the same organs. As such, there is some crossover between human and canine medicine. The use of Benadryl is one such case.

Why Would I Give Benadryl to a Dog?

Allergic problems of all sorts are common to dogs, and that’s where the usefulness of Benadryl shows itself. If you don’t know what Benadryl is, it’s actually a trade name for a substance called diphenhydramine.

Diphenhydramine is an antihistamine, which means that it fights the substances which cause allergic reactions. Histamines, oddly enough, are part of your body’s natural defense system. However, they are also the source of your irritations.

Things like sneezing, itching, and weeping are ways in which the body can rid itself of allergens. The sneeze is meant to flush allergens from your nose. The itch is meant to make you scratch the allergens off your skin. The weeping flushes the eyes similarly.

A brown Pitbull is sad

However, when you have already identified and removed the source of the reaction, you don’t need these unpleasant reactions to exacerbate your issues. All of this applies to a dog just as well as it applies to a human.

Benadryl is beneficial for dogs who are suffering from an allergic reaction because it will treat most of the symptoms. These symptoms include swelling, itching, hives, redness, runny nose, watery eyes, coughing, and sneezing.

Sometimes, Benadryl is also used in the treatment of mast cell tumors. When these tumors are removed and broken down, the dog’s body reacts with a huge histamine release. Obviously, this makes the use of an antihistamine necessary.

Some people choose to give their dogs diphenhydramine as a soothing agent. For dogs that suffer from frequent motion sickness, this medicine is said to provide relief. Some have also used it as an anti-anxiety medication since it does tend to calm an animal.

I would recommend against using Benadryl as an anxiety medication. Diphenhydramine is an antihistamine first and foremost. The soothing effect is the result of the drowsiness factor, a side effect which is listed on every bottle of Benadryl.

This is why it is not recommended to drive a motor vehicle within several hours of taking this medicine. If your dog has some anxiety issues, drugging them up is not going to help, and could end up causing serious health problems.

Anxiety problems in a dog are often simply the result of human behaviors. It is the nature of a dog to mold itself to the ways of its master. As such, a dog that has been abused or neglected will tend to be much more fearful and anxious.

Anti-anxiety medications cannot remove the underlying psychological trauma and are thus nothing more than a band-aid on a larger issue. Your dog probably just needs more attention, more affection, and possibly a better diet.

There is some argument for the use of diphenhydramine for motion sickness. I have a dog that has a terrible problem with motion sickness. Every time I try to take her anywhere, I can be sure that a puke-fest will ensue…all over my car.

That being said, I think I would rather just put down some newspaper in the floorboard, rather than to medicate my pet without a real medical need. However, extreme cases of motion sickness might make this medicine handy as a short-term solution.

Benadryl Is Not Officially Approved for Animal Use

A cute dog on a yellow sofa

It should be noted that the FDA (Food and Drug Administration) has not approved Benadryl for veterinary use. However, the process of approval is a long and complex one, so it’s not that surprising.

Given the lack of FDA approval, it is surprising to see that a number of studies have been done on this subject. Diphenhydramine has been tested on canines repeatedly, and the results have been published in respected publications.

Since the studies have generally shown it to be safe, we can only assume that there is a bureaucratic hold-up. I have personally given Benadryl to dogs, cats, and even a lizard, so I am convinced that it is safe if used in the proper dosage.

Benadryl Is Commonly Used by Many Veterinarians

In spite of the FDA’s lack of approval, many veterinarians use diphenhydramine to treat allergic symptoms. For mild cases of allergic irritation, it would be difficult to find something more appropriate.

Obviously, a severe allergic reaction would require a much more serious remedy. If there is no need to bring out the heavy artillery, your vet might decide that Benadryl (or something much like it) is a good choice.

Are There Any Side Effects?

Diphenhydramine has a tendency to cause drowsiness. It has this effect on both humans and dogs. Benadryl has long been known for its tendency to cause mid-afternoon naps. Likewise, your dog is likely to get a little sleepy.

That being said, there are certain medical conditions that can be complicated by the use of an antihistamine. These include glaucoma, heart issues, prostate issues, bladder obstruction, seizures, hypertension, allergic lung disease, and pregnancy.

If any of the above applies to your dog, you should not use Benadryl or any other form of diphenhydramine. There are plenty of alternatives that can take the place of this medication if it seems dangerous to the health of your dog.

Other common side effects of diphenhydramine include dry mouth, trouble urinating, excessive drooling, increased heart rate and quickened breathing. So, if you see just a little bit of any of these, don’t worry too much. These are completely normal.

What Does a Benadryl Overdose Look Like?

You need to know the signs of diphenhydramine overdose so that you can take action immediately if your dog shows these signs. The first thing to look for is a rapid heartbeat, even if the dogs’ body is at rest.

If your dog has taken too much Benadryl, their pupils will be extremely dilated. They will probably be breathing heavily, and they will likely seem agitated. Constipation also tends to result, although this is a less obvious sign.

In extreme cases, Benadryl overdose can lead to seizures and even to death. There is at least one study that proves the possibility of fatal diphenhydramine poisoning in a canine, but these researchers were looking at a deliberate case of animal murder.

It is safe to say that it would take a pretty big dose to kill your dog, but this will vary somewhat depending on what breed your dog may be, and upon how old they are. Obviously, puppies and small dogs are more at risk.

In certain rare cases, a dog might have an allergic reaction to the Benadryl. It is very interesting to consider that diphenhydramine, a useful medicine against allergic reactions, will actually cause a reaction in certain cases.

The Importance of Dosage:

A cute dog lying near an owner

Since we are using Benadryl in a manner that was not intended by its makers, it is very important to exercise caution. While I have been unable to find any cases of dogs being harmed by diphenhydramine, it always pays to be on the safe side.

The safest dosage is 0.4 milliliters for every pound of your dogs’ weight. So, for instance, if your dog weighs 30 pounds that would be 12 Ml of liquid. Make sure to weigh your dog accurately before figuring the dosage.

Be careful when you buy your Benadryl because there are some extra-strength versions that might be harmful to a dog even when used at normal dosages. There also might be special formulations designed for special problems, so avoid these too.

The best way to choose the right product is to make sure that it contains no active ingredients other than diphenhydramine. Generic versions of Benadryl are still based on the same active ingredient and are usually suitable for our purposes.

What if you aren’t using liquid? That’s a good question. If you are using solid tablets, you will likely have an easier time getting your dog to eat the medicine. The formula to follow here is 1 milligram for every pound of your dogs’ weight.

So for a 30-pound dog, you would use 30 Mg. For those of you that use only the metric system, this comes out to about 2 milligrams per kilogram. That being said, the dosage can be as high as 4 milligrams per kilogram if the situation calls for such.

Diphenhydramine and Benadryl are also available in the form of creams, ointments, gels, and sprays. These products are meant for external use only, and so you don’t have to be quite as careful about dosage. Just use enough to cover the affected area lightly.

If you are using a combination of these products, take special care and lower the dosage on both products. Remember, these products are all going to end up in the same bodily system. In general, combining these products might be a bad idea.

How Can I Test This Medicine Without Risking My Dogs’ Life?

If you are not able to find or afford a quality veterinarian, you may have to do a small test to figure out if your dog is hyper-sensitive or allergic to this medication. If done properly, this method is safe and effective.

Start by getting a little bit of the Benadryl cream. A gel or spray would also work. Shave a tiny part of your dog’s skin and apply the product. The shaving is necessary so that you can see the results as clearly as possible.

You could just apply the cream to their belly, as these are usually free of hair, but the skin of a dog’s underbelly tends to be quite sensitive. As such, I try to avoid doing a test in that area.

When you apply the product for the first time, use only a tiny amount. Check your dog after a couple of hours and see if the medicine has irritated their skin. If this is the case, do not use diphenhydramine on your dog again.

If there is no irritation, apply the product again. This time, add a little bit more. As before, observe the dogs’ skin after a few hours to determine results. If several tests are performed and no skin irritation is observed, we can safely rule out an allergy.

When you move to the internal dosing, do as before and start with a tiny amount. Make sure you are well below the normal recommended dosage. Observe your dogs for any signs of a bad reaction (listed above), and gradually bring them up to the standard dosage.

Conclusion: Always Play It Safe

It is important that you always consult your veterinarian before using any kind of medicine on your dog. At the very least. You should make a phone call and check to see if your vet would recommend against the use of Benadryl.

While this medicine is safe for most dogs, your vet will be familiar with your dog’s overall health. As such, they can do a better job of determining whether or not this medicine is right for your pet.

With a few cautions and a little common sense, this can be a useful remedy. I would stop short of endorsing this remedy 100%, but it does seem to be effective, and most veterinarians seem to agree that it is safe. So I say instead: Use but use with care.

1 thought on “How Much Benadryl Should You Give Your Dog?”

  1. I love my dog but I don’t usually have the money to pay vet bills. Any suggestions? There is no vet where I live that let’s a person make payments!!


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