How Much Benadryl for a Dog: Treat Allergies and Motion Sickness the Right Way

giving behadryl to a dog
Anna Smith
Written by Anna Smith

Just like any other member of the family, our dogs can get sick. We know how very tempting it can be to reach into the first aid cabinet and treat the dog ourselves—especially if vet help is not readily available for one reason or another. There are human medications that are safe for dog use, and Benadryl is one of them. But before you administer any, it’s important to know how much Benadryl for a dog is safe and how much is too much.

Dogs can react to medicine very differently from humans, and the wrong dosage can be fatal. However, as long as it is administered properly, human medicine like Benadryl can be given to your pooch to treat allergies, travel anxiety, and motion sickness.

behadryl pills

When it comes to giving your dog human medicine, it is always best to consult the vet first, but if all you need is a general guideline on Benadryl dosages for dogs to make sure you’re helping your dog instead of harming him, you’ll find what you need right here.

In this article, we will uncover exactly how much Benadryl is safe for a dog. We will also give you tips on how to administer Benadryl the right way. You’ll also need to know the possible side effects of the drug on your pooch so that you know what to expect.

What Does Benadryl Treat In Dogs?

dog sneezing

First thing first, Benadryl is really safe for dogs. It contains an active ingredient called diphenhydramine that is safe for dogs to ingest—unlike other cold, cough, or flu medicines.

When dogs are given Benadryl, it acts like an antihistamine that reduces the effect of histamine in the body. Therefore, Benadryl is used to treat all sorts of allergies. Benadryl can alleviate symptoms like:

  • Runny nose and eyes

  • Coughing

  • Sneezing

  • Hives

  • Swelling and inflammation

  • Redness

  • Anaphylactic reaction

See Also: Dog Allergy Testing

This medication can also be given to dogs with mast cell tumors to help relieve effects of the massive histamine dose released by mast cell degranulation. For this treatment, Benadryl is used as an adjunct treatment.

Veterinarians also give diphenhydramine during heartworm treatment as it as it helps prevent allergic reactions due to the therapy.

Benadryl can also cause drowsiness in dogs, which is why it is commonly used to calm anxious pets. Diphenhydramine can relieve symptoms of mild to moderate anxiety due to travel and can help relieve motion sickness in the car or an airplane.

See Also: Dog Car Sickness

Perhaps you’re asking: “How much Benadryl for a dog to go to sleep?” For the answer, you should check out the table below.

How to Give Benadryl to Your Dogs

weigh pug up

Before giving your dog Benadryl, it is important to make sure that the product contains only diphenhydramine. In some countries, this ingredient has fallen out of use. In the UK, for example, their Benadryl contains cetirizine—which might not be safe for dog use.

Now that you’ve ensured that diphenhydramine is the only ingredient in your Benadryl, here are the steps you need to follow when giving your dog this medicine:

Step #1: Determine the Right Dosage Based on Your Dog’s Weight

The first step is to weigh your dog. The amount of medicine your dog needs depends on his size. Find out the answer to your question about how much Benadryl for a dog in mg by perusing the table below:

Size of the Dogmg (milligrams)
30 lbs. or smaller10 mg per dose
30 - 50 lbs.25 mg per dose
50 lbs. and over50 mg per dose

If you want to be more precise, you can follow this simple formula: 1mg of Benadryl for every 1 pound of body weight. If you’re asking how much Benadryl for a 10-pound dog, the answer is 10mg. or 16 mg if he is 16 lbs. and 35 mg if he is 35 lbs. The typical dose is three times a day every 8 hours.

Note that the table above only applies in general situations. To be 100% sure, you should go to your vet first before administering Benadryl or any other medicine. The time-release effects of drugs are not absorbed the same way by dogs as humans, so it might affect the dosage.

Also, your dog’s condition and other medication can affect the efficiency of the drug. For example, your dog might be taking medicine for joint pain or other medication due to injury or surgery. Different kinds of drugs react differently with each other and mixing them together with Benadryl could have adverse effects on your dog’s health.

If you’re wondering how much children’s Benadryl for dog is ideal, the answer also varies because this variety is best suited for very small dogs. You have to be very careful when it comes to puppies and their medicine because they are not yet fully developed.

Step #2: Choose Liquid or Powder

Once you know your dog’s weight and you have an approximation of the dosage based on the table above, select the right kind of Benadryl for your dog. You can choose between liquid and powder Benadryl.

For those wondering how much liquid Benadryl for a dog is ideal, we would like to say that it is generally easier to give dogs the drug in pill form because dogs don’t like the taste of liquid Benadryl.

Also, if you want to know how much Benadryl for a dog in ml is ideal, the answer is a bit trickier because the strength statement of every liquid medicine bottle is different, and that affects the conversion from mg to ml. You should consult the vet to get a precise answer.

On top of that, liquid Benadryl also contains alcohol—which might not be safe for dogs. Ideally, the Benadryl should be in pill or capsule form and should only contain diphenhydramine as an active ingredient.

Step #3: Help Your Dog Take His Meds

sneakng the benadryl in ham

Now that you have the right dosage, you need to sneak it into their food so that your dog will take his medicine without a fuss. It is possible to give your dog Benadryl without food, but it is easier this way, and it also decreases incidents of drooling and vomiting.

You can sneak the Benadryl in a piece of bread slathered generously with peanut butter. Your dog will happily gobble it up by himself, and he will be on his way to feeling better. If you’d rather make him swallow the pills directly, check out the best way to do that in the article below.

See Also: How to Get a Dog to Swallow a Pill

Step #4: Monitor the Aftereffects

labrador dog is sick

Watch closely for your dog’s reaction. Benadryl is generally safe—especially if the correct dose is administered—but any medication can cause a reaction if your dog is allergic to it.

Instead of giving your dog his entire Benadryl dose the first time, test it first. Give him a small dose of Benadryl first and then wait a couple of hours before giving him the whole dose. This should rule out Benadryl allergy on their part.

Watch out for stomach issues like vomiting and diarrhea. You should also take note of behavior changes like disinterest in food or trouble breathing or a fast beating heart. Call your vet if your dog is experiencing any of these reactions.

On the other hand, there are some mild side-effects that you shouldn’t be too worried about—the most common of which being drowsiness. This is also the reason why Benadryl is given as an anti-anxiety medication as it calms both dogs and humans down. In fact, some companies market diphenhydramine as a sleep-aid for people.

The second most reported side-effect is disorientation. This is why it is important to observe your dog after giving him the medication. Disoriented dogs can be dangerous if left unsupervised. It is also good to note this before giving him a second dose so that you are prepared.

Other side-effects include:

  • Dry mouth

  • Breathing problems

  • Lack of appetite

  • Agitation

  • Urinary retention (not peeing)

  • Constipation

  • Increased heart rate

  • Hypersalivation

  • Sedation

Most side effects occur within one hour after administration of the drug, so it is important that your dog is monitored during this period.

If your dog is not suffering from any of the above complications, repeat Step 3 again until there are no more symptoms. However, if your dog is still unwell after 48 hours, it’s time to consult the vet.

Do’s and Don’ts of Giving Benadryl to Dogs

breaking down the tablet

Giving your dog Benadryl is safe, but it is still important to be careful. Keep these tips in mind when giving your dog a dose of this medication.


  • Follow the right dosage for your dog. It is advisable not to exceed three doses per day.

  • Break down the tablet before hiding it in their food so that they won’t notice the taste. If possible, be generous with the peanut butter or give it with their favorite food or treat so that they will be more inclined to finish the whole snack or meal.

  • Make sure that your pet has a full stomach before ingesting Benadryl. The drug can cause a loss of appetite or nausea so make sure that they are well fed.

  • Make sure that the label only mentions diphenhydramine as the active ingredient before giving your dog the Benadryl.


  • Give Benadryl to a puppy without consulting a vet. Puppies are like human babies and, like them, there are medicines that they cannot take.

  • Let your dog take a human cough, cold, or sinus medicine. Diphenhydramine is safe for humans and dogs, but not all medications are safe for dogs.

  • Give your dog liquid Benadryl. If possible, give your dog pills or capsules instead. Liquid Benadryl has a high concentration of alcohol which might not be safe for dogs. Also, most dogs don’t like the taste.

  • Exceed the recommended dosage. Overdosing can be dangerous and can lead to fatalities. The topic of overdosing will be explored further below.

Possible Dangers of Giving Benadryl to Dogs

pregnant dog lying

It is possible to overdose on Benadryl. The most dangerous symptom of overdose is hyper-excitability of the central nervous system (CNS). This can be deadly. If you think your dog has overdosed on Benadryl, contact your veterinarian at once.

Symptoms of overdose you need to watch out for include:

  • Dilated pupils

  • Agitation

  • Rapid heartbeat

  • Seizures

It is also possible for your dog to be allergic to Benadryl. If you think your dog is having an allergic reaction to the medication, contact your vet immediately. Keep an eye on your dog if it is his first time taking Benadryl to make sure that he is not allergic to it.

Do not give Benadryl to your dog without consulting a vet if he has the following conditions:

  • Severe heart failure

  • Hypertension

  • Pregnancy

  • Allergic lung disease

  • Bladder neck obstruction

  • Prostatic hypertrophy

  • Angle-closure glaucoma

Wrap Up

giving pill to a dog

Giving Benadryl to dogs can help alleviate symptoms that they are experiencing and make them feel more comfortable. It will also help calm you down as you watch them deal with their allergies.

Some dogs are also administered this drug when they suffer from motion sickness, and they need to be calm for a road trip or an airplane ride. Benadryl is also used as therapy medication for other conditions like tumors. Benadryl is a common drug. However, it is still important to be vigilant.

As stated above, Benadryl has certain side-effects such as disorientation and loss of appetite that could be dangerous if it is not monitored properly. The wrong dose or overdosing can also become dangerous for your dog, so being precise is very important if you’re treating your dog without consulting a vet first.

In the end, it is still better to err on the side of caution and bring him to the vet if he is sick. If your veterinarian prescribes Benadryl, he/she will be able to come up with a more precise dosage and instructions on how and for how long you need to administer the drug. Your vet is also the best person to advise you on how you can care for your pet while he is sick.

Dogs are faithful companions and as such are worthy of our care and affection. Knowing how to properly take care of them when they are sick is the least we can do for our best friend. Keeping the above tips in mind will help you take care of your dog when he is sick and help prevent untoward incidents in your home.

Have you tried giving Benadryl to your dog? How did he react? Do you think you will still give this medicine to your dog in the future? Tell us by leaving your comments below. Before you go, we recommend you check out this article on giving dogs fish oil to keep them in good health and prevent unwanted illnesses.

About the author
Anna Smith
Anna Smith

Anna Smith resides in beautiful Santa Monica, CA, where she works as a Pet Nutrition Expert in a leading retail pet store. She is responsible for nutritional strategies for different breeds and development of new products on the market in compliance with Association of American Feed Control Officials. Anna's passions are education about proven methods and best practices in the industry and her dog Max, who is always well-fed.