HomeBehavior & trainingCan You Give a Dog Benadryl? Appropriate Benadryl Uses for Dogs

Can You Give a Dog Benadryl? Appropriate Benadryl Uses for Dogs

by Dr. Amy Fox, DVM, | February 27, 2024

Can You Give a Dog Benadryl? Appropriate Benadryl Uses for Dogs

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Benadryl is an antihistamine that can treat allergies, motion sickness, and temporary anxiety in some dogs. It is safe for many dogs when given at the correct dosage, but it is important to consult with a veterinarian before giving it to your dog to ensure it is safe for your dog, especially if they take other medications or have underlying health problems. Benadryl is not a cure for any underlying medical condition and should only be used as directed by a veterinarian.

Like all medications, Benadryl can cause unwanted side effects in some dogs and may cause adverse reactions in dogs with certain underlying health problems. If your dog experiences any side effects such as agitation, diarrhea, or loss of appetite, stop giving them Benadryl and contact your veterinarian.

The good news is that this medication (the generic name for which is Diphenhydramine) is readily available without a prescription in pill, tablet, and liquid formulations, and, most of the time, your vet will recommend that you purchase the same Benadryl used for humans at your local pharmacy. While there are a few dog-specific brands of Benadryl, these may be more expensive or harder to find. So, once you know it is safe and effective in your dog, Benadryl is great to keep on hand as part of your doggy first aid kit.

Benadryl’s Purpose and Calming Side Effect

Benadryl is primarily an antihistamine, which means it blocks the effects of histamine, a chemical released by certain cells of the immune system. The release of histamine triggers many unpleasant effects in the body, including inflammation, itchiness, swelling, and constriction of the airways. Antihistamines like Benadryl block this pathway and reduce those unpleasant effects, with varying degrees of success.

The main reason vets prescribe Benadryl for dogs is to treat allergies and/or itchy skin. It also can be used to reduce nausea and prevent motion sickness due to the effects it has on the brain. There are other drugs that have similar effects and may be more effective in dogs, so your vet may recommend a different antihistamine depending on your dog’s specific condition.

Occasionally, Benadryl is prescribed as a mild sedative or calming agent for dogs because a common side effect of this medication is drowsiness. That can help dogs feel sleepy, for example, during travel. It is not a preferred drug for this purpose because there are many other medications and behavior modification techniques that have specific anti-anxiety effects and are more reliable.

While many dogs will experience drowsiness, Benadryl can also have the opposite side effect and cause agitation in other dogs. If you are planning to try to use Benadryl for its sedating effects, try it at home prior to the event you really need it for to make sure it works on your pup.

Is Benadryl Safe For Dogs?

Many people wonder if Benadryl can hurt dogs, but Benadryl is safe for most dogs at the prescribed doses. While it can cause a number of side effects, most are mild and resolve as soon as the medication is discontinued. It can be more risky for certain dogs with underlying health problems such as dry eye, glaucoma, urinary problems, or seizure disorders since it can exacerbate these conditions. Here are some of the common Benadryl side effects in dogs:

  • Drowsiness

  • Agitation

  • Dry eye

  • Urinary retention

  • Loss of Appetite

  • Nausea/Vomiting

  • Constipation

  • Diarrhea

Benadryl can also be harmful if the dose is too high and/or if a pet parent is using Benadryl to treat a medical problem at home without veterinary guidance. For example, a dog that has a severe allergic reaction with facial swelling and/or hives may not respond to Benadryl alone and likely will need stronger medications to stop the reaction. These reactions can snowball and become life-threatening if a dog develops difficulty breathing, so trying to treat at home with over-the-counter Benadryl could put a dog at risk for serious complications. Any dog who is in distress or develops a new medical problem suddenly needs to see a vet first to get a thorough exam and diagnosis before trying an over-the-counter medication like Benadryl

How often can you give a dog Benadryl?

The Merck Veterinary Manual recommends administering the correct dose of Benadryl two to three times a day, but this dosage can vary depending on a dog’s weight and any other medical conditions they’re experiencing.

How much Benadryl can I give my dog?

A dog’s Benadryl dosage is based on their size and weight and may vary based on the condition being treated, so it is important to discuss your particular dog’s situation with your vet and troubleshoot any issues that may be related to dosing. Typically, dosages start around 2.2 milligrams per kilogram, which is one milligram per pound of body weight. A basic formula to figure this out is to use your dog’s weight in pounds as their dosage — so, a dog who weighs 10 pounds would receive a dose of 10 milligrams.

Can You Give a Dog Benadryl for Anxiety?

Yes and no. Benadryl is not an anti-anxiety medication, so it does not actually help your pup to feel less anxious. For dogs that are drowsy after taking Benadryl, the sleepiness masks their anxiety and makes them too tired to act anxious, but is it not actually helping the underlying problem. This may be fine in a pinch if, for example, you suddenly have to travel with your pet and can’t see your vet in time to get a more effective medication. However, keep in mind that not every dog is sedated by Benadry,l so it may not have the desired effect on your pooch at all.

Anxiety in dogs is a complex issue, just like in humans. It can be triggered by many different things, and dogs often need a multifaceted treatment approach. This may include behavior modification training to desensitize them to their triggers, using exercise and positive reinforcement to provide structure, and prescription medications to actually reduce their anxiety level enough for them to work through these other techniques. A dog with moderate or severe anxiety will not make progress with Benadryl alone. These can be challenging cases and are best treated with the help of your vet and a veterinary behaviorist.

Drug-Free Ways to Calm Your Pet

While many websites talk about how safe Benadryl is, responsible pet parents will always check with their vet before dosing their dogs with any medication. There are times when drugs will be a crucial part of their treatment plan, and for those cases, specific anti-anxiety drugs or sedatives will be the most effective choices. If you have a very active or anxious dog, there are also other important steps to take to work with them on these behaviors. These include:

More exercise

Giving your active dog plenty of time to burn off their energy is a great way to calm them down. Long walks, time at a doggy daycare, trips to the dog park, agility training, or tossing a ball around your yard are a few ways to allow your dog to be more active. Dogs need physical activity just like people, and some breeds need a lot more than others. If you have a high-energy dog, be sure you are giving them constructive outlets to exercise — otherwise, they may find destructive habits that are not to your liking.

Prevent boredom

Giving your dog’s brain a workout is just as important as giving their body a workout. A puzzle toy that makes your pup work for a treat is a great way to engage their brain and help curb boredom. Other ways to provide enrichment include training sessions to teach your pup new cues and tricks, time for socialization with other dogs, and sensory experiences with music, different scents, and/or flavors.

Proper training

One common complaint among dog parents with very active dogs is that it’s difficult to walk them because they are always pulling on the lead or otherwise engaging in unwanted behaviors. This conduct can be modified with proper training. Even the most energetic dogs can be taught to "leave it," "stay," and "sit," and most pet parents are surprised how quickly the training kicks in. Training is also very important for anxious dogs as behavior modification techniques can help your dog overcome fears, desensitize to triggers, and build confidence. Working with a behaviorist or trainer is a good idea in these cases as your dog’s anxiety should be properly diagnosed in order to craft the most effective training approach.

Change their food

This is one option that many pet parents don’t consider, but food can impact your dog’s behavior. It is important to ensure your dog is eating a complete and balanced diet suited to their life stage and needs. Dogs who are not eating an appropriate diet could be at risk for nutritional deficiencies, which can sometimes affect their behavior as well as their overall health. There are even some treats and diets out there formulated to provide calming effects, although many of these have not been rigorously studied to know if they are truly effective. If you’re not sure how to choose the best food for your dog, check out our dog and cat nutrition page or talk to your vet for advice.

Can You Overdose a Dog on Benadryl?

Yes, you can overdose a dog on Benadryl. An overdose can range from mild unwanted side effects to more serious health scares depending on how much a dog ingests.

It is very important to keep this medication, and all medications, safely out of your dog’s reach. Some human medications are highly toxic to dogs and even small amounts can cause fatal complications, so it is good to get into the habit of keeping all medications secured.

Also, be sure that if you are giving Benadryl to your dog, the only ingredient in the product is Diphenhydramine. Some products contain a combination of ingredients such as an antihistamine combined with a decongestant and/or fever reducer, and these other medications can be highly toxic to dogs.

What are the symptoms of Benadryl overdose in dogs?

If you suspect your dog has ingested too much Benadryl, whether by accident or a miscalculation, be sure to note down as much information as possible, including the specific medication your dog received, any other ingredients in the product, the strength of the medication, the formulation (such as pill versus capsule versus liquid), what time you believe the overdose occurred, and how much of the medication you believe your dog ingested. All of this information will help your vet create a treatment plan.

It is best to get your dog to the vet right away if you believe an overdose occurred instead of waiting for symptoms to set in. However, some common symptoms in dogs of an overdose of Benadryl include:

  • Agitation

  • Sedation

  • Excessive drooling

  • Rapid breathing

  • Rapid heart rate

  • Tremors

  • Seizures

  • Vomiting

Commonly Asked Questions

At what age can you give dogs Benadryl?

Benadryl is safe to give to dogs four months of age or older and may be used in younger dogs with your veterinarian’s supervision. Benadryl’s effects have not been thoroughly studied in very young puppies, so it is not clear if it’s completely safe for them.

Can you give a dog Benadryl for itching?

Yes, Benadryl is an antihistamine that is sometimes prescribed to dogs for itchy skin. It is always important to get a diagnosis from your vet first since certain skin conditions can be cured with a specific treatment, and Benadryl just temporarily relieves the itch. Also, some other antihistamines may be more effective in certain dogs.

Can you give a dog Benadryl for allergies?

Yes, Benadryl is an antihistamine that is sometimes prescribed for allergies in dogs. It is always important to get a diagnosis from your vet first since other conditions may seem like allergies but require different treatments. Also, some other antihistamines may be more effective in certain dogs.

Can you give a dog Benadryl for bee stings?

Yes, Benadryl is an antihistamine that can help with mild swelling related to bee stings in dogs. A dog that is stung by a bee and is acting completely fine may not need any treatment at all. A dog that has more severe signs of an allergic reaction, including any swelling of the face or difficulty breathing, needs to see a vet right away for more intensive treatment.

Can you give a dog Benadryl for pain?

No, Benadyl does not provide any pain relief for dogs. A dog that is in pain needs to be evaluated right away by a veterinarian in order to receive medications that are safe and appropriate to treat its pain. As a reminder, many human pain medications are highly toxic to dogs and should never be given to dogs


Diphenhydramine Intoxication in a Dog

Oral antiallergic activity in ascaris hypersensitive dogs

The influence of an antihistamine drug on the release of histamine in the unanaesthetized dog

Frontiers in Immunology:

The Role of Histamine and Histamine Receptors in Mast Cell-Mediated Allergy and Inflammation: The Hunt for New Therapeutic Targets

ASPCA Poison Control: Can you give your pets an Antihistamine

ASPCAPro: Antihistamine Toxicosis

Journal of the American Veterinary Medical Association: Evaluation of Diphenhydramine as  Sedative for Dogs

Dr. Amy Fox, DVM

Dr. Amy Fox, DVM

Amy Fox, DVM is a small animal veterinarian in New York City. She has worked in many different settings including shelter medicine, emergency medicine, general practice, and animal cruelty and forensics. She is especially interested in nutrition, preventative medicine and care for senior pets. Dr. Fox also enjoys writing about veterinary medicine and teaching. In her free time she loves to cook, garden, and go for long runs.