How Much Benadryl Can I Give My Dog?

Why pet owners are switching to online vet care with Dutch

  • Prescriptions delivered free to you

  • Fast access to Licensed Vets over video

  • Unlimited video visits and follow-ups

As a dog parent, it’s only natural that you wish to provide your pup the best life possible. However, from time to time, your dog may develop an illness or get hurt and you may want to give them Benadryl. How much Benadryl can you give your dog? 

Benadryl is a very common medication that is sold over the counter. As an antihistamine, there are many people who take Benadryl to deal with allergic reactions, itching, cold symptoms, and even pain. There are also some situations where Benadryl can help with insomnia. Even though Benadryl can be beneficial to people, it does not necessarily mean that it is always appropriate to give to dogs.

If you decide to give your dog Benadryl, you must make sure that you do so safely. It is a good idea to reach out to your veterinarian to make sure you have a safe dose in mind. If you are curious about how much Benadryl can be safely given to dogs, take a look at the information below.

What Is Benadryl Used For?

Common conditions in dogs that can be treated by Benadryl

There are several common situations in which a pet owner can give their dog Benadryl.1 A few examples include:

  • Hives: If you notice that your dog is developing hives, they could be having an allergic reaction to something. Hives can be a symptom of a more serious reaction, but you may want to start by giving your dog Benadryl. Don't forget to reach out to your veterinarian to make sure there isn't something else you should be doing to address the situation. 
  • Swelling and inflammation: You might also notice that your dog has developed swelling and inflammation. Swelling and inflammation could be signs of an underlying allergic reaction as well. Benadryl could help treat this issue, but you may want to reach out to your veterinarian to learn more about the problem. 
  • Runny nose and eyes: If you notice that your dog has a runny nose or watery eyes, it could be a sign of seasonal allergies. Even though there are plenty of other issues that can cause this problem, you might be able to help your dog by giving them Benadryl. Remember that Benadryl can make your dog sleepy, so be sure to keep an eye on them. 
  • Coughing: Some pet owners give their dogs Benadryl if they are coughing. There are countless reasons why a dog might start coughing, and Benadryl is a helpful cough suppressant. Remember to talk to a professional to get to the root of why your dog is coughing so much. 
  • Sneezing: If you notice that your dog is sneezing continuously, you might be looking for a way to make them more comfortable. Benadryl could be beneficial in this situation. Do not forget to talk to your vet to make sure you know why your dog has started coughing. 
  • Anaphylactic reaction: Benadryl is sometimes a part of the treatment plan for an anaphylactic reaction. Anaphylaxis is a very severe allergic reaction. It can have a significant impact on your dog's ability to breathe, and it could create a life-threatening situation. Your dog will need to be treated by a veterinarian with adrenaline shots and IV fluids, but Benadryl could be a good emergency fix until you can get to the animal hospital. Always take your dog to an emergency vet if you feel like their allergies are making it hard for them to breathe.2

These are just a few of the most common examples in which it can be helpful for you to give your dog Benadryl. Every dog is different, and it is important for you to think carefully before you start giving your dog Benadryl. Not only does your dog need the accurate dose of Benadryl to safely treat their condition, but you should also make sure that they are not suffering from an underlying medical condition that needs a different treatment plan.

If you are wondering how much Benadryl to give a dog, it is critical to talk to a veterinarian about what dose is appropriate. It depends on your dog and their medical history.

Recommended Dosage For Dogs

So, how much Benadryl can I give my dog? You need to make sure you follow all of the recommended guidelines noted by your veterinarian. No matter how confident you are in your measuring skills and mathematical calculations, you always need to talk to your veterinarian before you give your dog Benadryl.

You can give your dog 0.9 to 1.8 mg of Benadryl for every  pound of their weight

In general, you should give your dog 2 to 4 mg of Benadryl per kilogram of body weight or 0.9 to 1.8 mg per pound of body weight.3 Here is an example calculation below:

Your dog weighs 100 pounds. 100 pounds x 0.9 mg of Benadryl = 90 mg of Benadryl. The recommended range is 90 mg to 180 mg of Benadryl per dose.

You can do the same calculation if you prefer to use kilograms. Remember that this is only the recommended dose. You may want to start with a lower dose, only increasing it if you feel like your dog is not getting any better. You also need to talk to your veterinarian to see if there are other issues you need to consider. For example, your dog might be taking other medications that can impact the rate at which their body metabolizes Benadryl. Most importantly, you must ensure that you keep your dog safe. 

You also need to understand how long it takes Benadryl to act and how often you should give your dog Benadryl. How often can I give my dog Benadryl? This is something that only a veterinarian can answer. Always talk to your veterinarian before you decide to give your dog Benadryl. 

Side Effects Of Benadryl

If you are curious about how much Benadryl to give a dog, you need to be aware of some side effects as well. Understand that the vast majority of dogs will tolerate Benadryl just fine. At the same time, there are a few common side effects that you might notice. 

Common side effects of Benadryl

Some of the most common examples of Benadryl side effects include3:

  • Drowsiness: Benadryl is something that will make just about anybody tired. Therefore, expect your dog to want to go to sleep after taking Benadryl, particularly if your dog is taking it for the first time. 
  • Dry mouth: Benadryl can also cause dogs to have a dry mouth. If you notice that your dog is continuously licking their lips, this could be the Benadryl working. You may want to provide your dog with some extra water after giving them Benadryl as well. That way, your dog will stay comfortable. 
  • Urinary retention: It is also not unusual for Benadryl to cause dogs to retain urine. If you notice that your dog is not going to the bathroom as often, you may want to give your dog a few extra minutes outside. Reach out to your veterinarian if you notice that your dog is still not going to the bathroom very often.
  • Hypersalivation: Benadryl can also cause dogs to develop hypersalivation. This means that your dog will produce an increased amount of saliva. If you notice that your dog is drooling more often, you may want to give them a bit more space to be comfortable. If you believe it is a more serious issue, consider reaching out to your veterinarian for more information. 
  • Increased heart rate: Benadryl can also cause a significant increase in heart rate. Pay attention to your dog’s body language and behavior. If they are exhibiting unusual behavior and seemingly in distress, notify your veterinarian as soon as possible.
  • Rapid breathing: Benadryl can also cause faster, more labored breathing in dogs. Your dog may be panting and using their stomach muscles to breathe. Keep a close eye on your dog and reach out to your vet with any questions or concerns.

These are just a few examples of the most common side effects caused by Benadryl. Even though these side effects tend to be relatively mild, it is also possible that your dog may develop more serious side effects as well. In some cases, your dog can even overdose.

Signs Of A Benadryl Overdose

If your dog is in danger of a Benadryl overdose, they will exhibit certain signs.4 To ensure your dog’s safety and well-being after taking Benadryl, look out for these key indicators:

  • Rapid heartbeat: A fast heartbeat can be normal, occurring due to excitement or after vigorous exercise, but a rapid heartbeat can be dangerous. If you notice a change in your dog’s behavior or that they are starting to panic, touch their chest to feel their heartbeat. If their heart is beating too fast for you to count, reach out to an emergency vet as they could be overdosing from Benadryl.  
  • Dilated pupils: Take a look at your dog's eyes. If you notice that your dog has dilated pupils, or pupils that cover most of their irises, there could be something wrong. Dogs’ eyes are very sensitive to light, so it is abnormal for your dog’s pupils to be dilated in a bright room. This could be a sign of a Benadryl overdose and should not be overlooked.
  • Agitation: Agitation is also a very common side effect of a Benadryl overdose. If you notice that your dog appears confused or anxious and cannot seem to sit still, they may be experiencing an overdose. 
  • Constipation: Constipation is also a telling sign of a Benadryl overdose. If you believe your dog is having difficulty going to the bathroom and they have not produced stool in a substantial amount of time, you may need to take them to the emergency veterinarian. Constipation is a worrying issue that could lead to more serious health complications. 
  • Seizures: If your dog is overdosing from Benadryl, they may be prone to seizures. There are different types of seizures, but the most common example is a tonic-clonic seizure. This takes place when your dog loses all control and begins to shake all four extremities continuously. This is an emergency, and you need to reach out to your veterinarian.

It is crucial to know the correct dose of Benadryl to administer to your dog. Always check with a veterinarian if you are unsure to avoid a Benadryl overdose. Knowing the telltale signs of a Benadryl overdose in dogs can also help you save your dog’s life in case of an error or emergency. Even if you give your dog the correct dose of Benadryl, you need to know how long the medicine stays in their system and how often you can give them Benadryl to ensure their safety.

Signs of Benadryl overdose in dogs

How Often Can I Give My Dog Benadryl?

So, how often can you give Benadryl to your dog? Even though the recommendation is 2 to 4 mg per kg of body weight, giving your dog Benadryl too frequently can also lead to an overdose. Typically, you are allowed to provide your dog the recommended dose two to three times a day as needed, but it is always good to err on the side of caution so that your dog has time to process the medication in their body.3 It is also important to remember that no matter what medication you are giving your dog, there are always side effects to consider.

If you want to give your dog three doses of Benadryl per day, you may want to stick to the lower end of the recommended range. On the other hand, if you are fine giving your dog one dose per day, then you may be able to increase it to the larger end of the recommended range above.

No matter how much you trust your math, you need to reach out to a veterinarian for clarification before you move forward. Even though Benadryl can be found over the counter, it is also possible for a dog to overdose on Benadryl. If your dog is prescribed any other medication, you need to pay even more attention as it could react poorly with Benadryl.

How Long Does Benadryl Last In A Dog?

If you are curious about how much Benadryl to give a dog, you may also be wondering how long Benadryl will last in their bodies. There are a lot of factors that will play into how long it takes your dog to metabolize Benadryl. Every breed is different, and your dog may have other medical issues that affect the situation as well. However, in general, you should expect the effect of Benadryl to last between eight and 12 hours in dogs.1 

If you believe that your dog is experiencing side effects stemming from Benadryl, you need to give your dog a few hours to metabolize the medication. Your dog should eventually make a recovery. However, if you believe that your dog is still having symptoms 24 hours after their last dose of Benadryl, it is time to reach out to your veterinarian. You need to make sure that your dog is not experiencing dangerous side effects or complications. Benadryl should wear off completely after 24 hours.

Dog in cone looking up into the camera

Factors To Take Into Consideration

Before you decide to give your dog Benadryl, you always need to talk to your veterinarian. You must make sure you are not overlooking anything important, and you need to make sure that Benadryl is safe for your dog. Some of the most important factors that you need to think about before you give your dog Benadryl include:

  • Other medications: If your dog is taking any other medications, you should always talk to your veterinarian to make sure that they are able to take Benadryl. Even though your vet should have a list of other prescription medications, you need to disclose any herbs, supplements, or over-the-counter medications as well. Your vet needs to ensure that Benadryl will not interact with anything else your dog takes. Always disclose all medications and supplements to your vet before you start giving your dog Benadryl. 
  • Possible underlying conditions: You also need to think about possible underlying conditions that could be causing your dog’s symptoms. Even though Benadryl may be able to address some of the symptoms they are experiencing, it will not necessarily fix the underlying condition. You need to talk to your vet to ensure your dog's symptoms are not a sign of something more serious. 
  • Prior medication history: Your vet may also ask you to think about other medications your dog has taken in the past. Your veterinarian will be curious about this because it can help them deduce how your dog will respond to Benadryl. Think about other medications your dog has taken in the past and how well they have worked. 
  • Possible allergies: If your dog has a history of allergic reactions, you need to talk about this with your veterinarian. Your veterinarian will want to gauge the possibility of your dog developing an allergic reaction to Benadryl. Even though it is unusual, a dog allergy is still something you need to be vigilant about. 
  • Potential side effects: Your veterinarian will also talk with you about possible side effects. Even though most Benadryl side effects are mild, there are rare situations in which dogs can develop more serious reactions. Your veterinarian will want to make sure you understand what to do in the event of serious side effects. 

After you have discussed these issues with your veterinarian, they should let you know if it is safe for you to give your dog Benadryl. Then, based on what your vet says, you can move forward accordingly. Remember that you must monitor how your dog responds to Benadryl. If you feel like something is changing, you should let your veterinarian know right away. 

How Much Benadryl Can I Give My Dog?: FAQs

There are several common questions that people ask about giving Benadryl to dogs. Some of the most important questions include:

What happens if I give my dog too much Benadryl?

If you give your dog too much Benadryl, you must be vigilant for signs of an overdose. There are several common symptoms of a Benadryl overdose in dogs. Some of the most common symptoms include a rapid heartbeat, dilated pupils, agitation, seizures, and constipation. If you believe you have spotted any of these symptoms, you need to contact an emergency vet as soon as possible. Your dog may need to go to the emergency room. You should always talk to your vet before you give your dog a new medication, including Benadryl. 

Will Benadryl calm a dog down? 

It is possible that Benadryl can help your dog calm down. One of the most common side effects of Benadryl is sedation. You may notice that your dog gets a bit drowsy after taking Benadryl. If you believe your dog needs help sleeping, you must talk to your veterinarian first. Make sure it is the best option for your dog before you start giving it to him or her. 

What’s the best way to sedate a dog?

You must talk to your veterinarian if you want to sedate your dog. Trying to sedate your dog on your own can be very dangerous. You run the risk of causing a dangerous reaction, so you need to work with your veterinarian closely if this is your goal. The only person sedating a dog should be a veterinarian, which can only be done in a very tightly controlled environment.

Dog sleeping on the ground with tongue out

Final Notes

Benadryl is a very popular medication and many people tend to use it to treat their own issues. Although it is sold over the counter, it is important to remember that it is still a powerful medication, especially when given to dogs. To safely administer Benadryl to your dog, you must understand when you can give your dog Benadryl, how much Benadryl you can give your dog, and how often your dog can have Benadryl. Knowing the signs of a Benadryl overdose can also help you save your dog in case of an emergency. 

If you want to learn more about giving Benadryl to your dog or other over-the-counter medications that dogs can safely consume, ask Dutch. Dutch is a powerful and accessible resource for all pet owners. Our licensed vets can teach you how to provide your dog with the care they need and come up with a treatment plan that best suits your canine companion. For example, you might be interested in using Benadryl to treat conjunctivitis in dogs. Or, you might be curious about what it means if you see yellow dog poop. Many people even turn to Dutch to answer the question, “what vaccines do puppies need?” 

Before you give your dog any medication for the first time, it is important to talk to your veterinarian. You can access a lot of helpful information on Dutch’s blog. To ensure you provide your dog with the quality care they need, take a look at everything that Dutch has to offer. 



  1. Burke, Anna. "Benadryl for Dogs." American Kennel Club, 23 Apr. 2021,

  2. Tizard, Ian. "Disorders Involving Anaphylactic Reactions (Type I Reactions, Atopy) in Dogs." Merck Veterinary Manual, Oct 2020,,-atopy-in-dogs.

  3. "Antihistamine Dosages." Merck Veterinary Manual,

  4. Malmanger, Ellen. "Benadryl Overdose in Dogs." PetMD, 29 Sept. 2021,

Memberships to keep your pet healthier

billed $132 yearly
20% off of all memberships
billed monthly

All memberships include:

  • Fast access to licensed vets
  • Virtual care for up to 5 pets
  • Customized Rx treatment plans
  • Unlimited video calls & follow-ups
  • Guaranteed low prices on medication
  • Free shipping on every order

Frequently Asked Questions

Who is Dutch?

Dutch is an online veterinary pet telehealth service, created by pet parents and board-certified veterinary specialists. We use a science-backed approach to provide pets relief for their everyday physical and behavioral health issues. Dutch connects you with licensed veterinarians over video chat and messaging to help you get care for your dog or cat quickly wherever you are — without the stress or expense of a vet visit. We also partner with pharmacies who can deliver prescription medication (in applicable states only) and over-the-counter treatments directly to your door. Dutch isn’t a veterinary practice or pharmacy, but a company that helps facilitate these services for pet parents to make veterinary care more accessible to all.

What is a visit with Dutch like?

When booking a video call with a vet, you'll be asked a few questions about your pet’s health issue. Depending on the issue, you may also be asked to fill out a longer questionnaire about their symptoms and share photographs of them so our veterinarians can better understand what’s going on. You’ll then pick an appointment time that works best for you.

During your video call, one of our licensed veterinarians will talk to you about the symptoms your pet is experiencing, ask you questions, review your pet’s medical history if you’ve provided it, and answer any questions you have. The vet will ask to see your pet and their environment. And they may ask you to perform some simple checks on them if needed.

After your video call, the vet will send you a message with a custom treatment plan to help your pet feel better, including a link to buy any recommended prescription or over-the-counter medications. Place your order and we’ll ship it free.

How much will it cost for Dutch to treat my pet?

The Dutch membership starts at $11/mo for unlimited access to the vet. No more long waits for appointments or surprise bills.

In addition to the base membership plan, our veterinarians may also recommend additional medication (Rx and/or OTC) that you will have the option of adding to your plan at an additional cost.