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Can You Give Dogs Benadryl for Allergies or Stress?

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Benadryl, also known as diphenhydramine, is an antihistamine often used to help both dogs and humans mitigate allergy symptoms and help them sleep. While many veterinarians believe that Benadryl is safe for dogs, it is also essential to consult your vet before giving your dog any product, especially if your dog is taking other types of medicine. 

Dogs and humans react differently to most medicines, though, so it is important not to assume your dog will respond to Benadryl the same way you do. Broadly, Benadryl is considered safe for your dog, but there are underlying conditions that may make it inadvisable, including low blood pressure, pregnancy, or cardiovascular issues.

How Does Benadryl Work? 

At the most basic level, Benadryl blocks histamines from the receptors in your body, relieving allergy symptoms. In dogs, Benadryl is most commonly used to help with canine allergic reactions such as itching and hives but can also help limit sneezing, red eyes, and a runny nose.

Benadryl can also be highly effective in mitigating issues with environmental allergies. Still, if your dog is struggling with breathing, Benadryl will not be as effective, and you should seek immediate advice from your veterinarian. If you decide to give your dog Benadryl, keep an eye on them to see if they have an adverse reaction to the medicine. 

One other common reason that your veterinarian may recommend Benadryl is for stress or anxiety, nerves, or motion sickness. If your dog is scared of loud noises or being in the car or is just generally nervous, it is reasonable that you may want to use Benadryl to sedate them. 

Temporary or occasional use is recommended, so there may be other more beneficial remedies for your dog that might calm rather than sedate. 

What Are the Side Effects of Benadryl on Dogs?

Some dogs actually have an opposite reaction to Benadryl and become more hyperactive rather than sedated. Other side effects include dry mouth, increased heartbeat, issues with urination, and even rapid breathing. 

Some signs that you gave your dog too much include tremors, constipation, being overly agitated, increased heartbeat, and dilated pupils. If you think you may have given them too much, reach out to your veterinarian or veterinary emergency clinic immediately. 

Finally, some dogs, just like some humans, may be allergic to Benadryl, so if you are giving your dog Benadryl for the first time, make sure that you keep an eye on them to see if they are negatively reacting. 

Are Time-Release Capsules of Benadryl Better for Dogs?

One important thing to note is that you should never use time-release capsules with dogs because dogs absorb medication differently than humans do. Time-releasing capsules could give your dog too much at one time and cause an adverse reaction or fatal overdose

Some liquid Benadryls contain alcohol, so make sure that if you choose a liquid version, you choose a non-alcoholic, children’s version as a safer option. 

What Can Dogs Be Allergic To?

Dogs, like humans, can develop allergies to a wide range of substances. This section will take a close look at common causes of allergies in dogs. 


Dogs can be allergic to ingredients in their diet, such as chicken, beef, grains, or dairy products. Food allergies can manifest as skin issues, gastrointestinal problems, or chronic ear infections.

Environmental Allergens

Pollens, molds, dust mites, and other environmental allergens can trigger allergic reactions in dogs. These allergies often lead to symptoms like itching, sneezing, and runny noses.

Insect Bites

Fleas, ticks, and mosquito bites can cause allergic reactions in dogs, resulting in itching, hives, or even more severe responses.


Like humans, dogs can have adverse reactions to medications, which may manifest as allergic symptoms, including rashes, swelling, or digestive issues.

Chemicals and Household Products 

Exposure to certain cleaning agents, detergents, or fragrances can also trigger allergic reactions in dogs, leading to skin irritations or respiratory problems.

What Induces Stress in Dogs?

Stress in dogs arises from a multitude of sources. Firstly, loud noises, including thunderstorms, fireworks, or disruptive construction sounds, can be profoundly distressing for our canine companions. 

Separation anxiety, another common trigger, occurs when dogs are left alone for extended periods, leading to heightened stress and anxiety. Changes in environments or moving to a new home can be unsettling for dogs, causing stress. 

Social stress is often induced through interactions with unfamiliar dogs or people, particularly affecting dogs lacking proper socialization. Medical issues, encompassing pain, illness, or general discomfort, can also induce stress in dogs. 

Finally, past traumatic experiences, such as accidents or abuse, may result in long-lasting stress, affecting the overall well-being of our furry friends.

Wrapping Up 

Benadryl, or diphenhydramine, can be a useful tool for managing allergies and stress in dogs. It blocks histamines, providing relief from allergy symptoms, and can also help calm anxious dogs. However, it’s essential to consult with a veterinarian before giving any medication to your dog, as individual reactions can vary.

Understanding the potential allergens and stressors in your dog’s environment is crucial for their well-being. Allergies can be triggered by various factors, including food, environmental elements, insects, and medications. Identifying and addressing these allergens can help improve your dog’s quality of life.

Stress in dogs can result from numerous sources, such as loud noises, separation anxiety, new environments, and medical issues. Recognizing the causes of stress and implementing appropriate strategies, including potential medication under veterinary guidance, can help alleviate your dog’s discomfort.

Always monitor your dog for any adverse reactions when using Benadryl, and seek immediate veterinary attention if you suspect an overdose or severe side effects. Ultimately, we at ElleVet believe that a veterinarian’s guidance is essential to ensure your dog’s health and well-being when using Benadryl or any other medication.


Antihistamines – NHS

Canine Allergic Disease | Cornell University College of Veterinary Medicine

​Dog Constipation: Causes, Diagnosis, and Treatment | AKC

Fatal diphenhydramine poisoning in a dog | NIH

The ElleVet Team
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