Every pet owner wants the best for their dog. Benadryl®, or diphenhydramine, is one of very few over-the-counter drugs designed for humans that some veterinarians may have pet parents administer to their dogs at home.

Benadryl® can be used to help keep your pup calm; it can also be used if your dog was stung by an insect, or is having a mild allergic reaction. While Benadryl® is generally well-tolerated by dogs, it’s not necessarily the answer to every issue. How much Benadryl® can you give to your dog, how often should you give it to them, and is it safe to use on your particular pet?

For some dogs, Benadryl® might have the opposite intended effect. It can make your pet more anxious, and should not be used with animals who have certain health conditions. We will discuss when Benadryl® is safe and effective to give to your dog, when different treatments should be used, and if your veterinarian is okay with it. Here are a few things to keep in mind before giving Benadryl® to your dog.

 What Is Benadryl®?

Benadryl® is an antihistamine that prevents the body’s H-1 receptors from reacting to histamine. It eases nausea and vomiting by inhibiting the brain’s vomiting center (your chemoreceptor trigger zone) and reduces how the body’s balance center (the vestibular apparatus in your ear) responds to motion.

Your veterinarian might recommend Benadryl® to your pup to treat or prevent mild allergic reactions, or to reduce the nausea and vomiting that’s associated with motion sickness. Benadryl® might also be recommended for vestibular disease. Your veterinarian might recommend allergy shots for dogs or other treatments besides Benadryl®.

 Is Benadryl® Safe for Dogs?

Benadryl® is safe for dogs under the strict direction of your veterinarian.

As an antihistamine, Benadryl® can be safe for dogs when used with guidance, based on your pet’s medical history and needs. It’s most commonly used to manage allergies, itching, mild anxiety, and nausea. It is also recommended for anxious dogs.

Before you decide to liberally give your dog Benadryl®, speak with your veterinarian and get their clearance first. Because of your dog’s health and medical history, a trusted vet must give the go-ahead.

 What Does Benadryl® Treat in Dogs?

Benadryl® can be a great treatment for dogs with mild or moderate allergies. In most cases, seasonal allergies, environmental allergies, food allergies, and reactions to snake or insect bites can be treated with Benadryl®.  It’s also commonly used to treat itchiness caused by skin allergies.

Benadryl® can treat or reduce many symptoms in dogs, including:

  • Coughing
  • Sneezing
  • Hives
  • Redness
  • Runny nose and eyes
  • Swelling and inflammation
  • Anaphylactic reaction

When Owners Shouldn’t Give Benadryl®l to Dogs

Always consult with your veterinarian before giving your dog any kind of medication or supplements. You don’t know how Benadryl® or other medications can mix with what your dog is currently taking, and your dog’s health could be adversely affected.

Benadryl® should be avoided if your dog has:

  • Certain health conditions
  • Cardiovascular disease
  • High blood pressure
  • Liver disease
  • Seizures
  • Allergies to antihistamines
  • Pregnancy or post-pregnancy
  • Conflicting medications
  • Antidepressants
  • Potassium supplements
  • Gastrointestinal medications prescribed by a vet

When Owners Shouldn’t Give Benadryl®l to Dogs

 What Kind of Benadryl® Should I Give My Dog?

Only give your dog Benadryl®  prescribed by your veterinarian, such as diphenhydramine capsules for dogs. Avoid liquid Benadryl® as it contains sodium which can cause side effects in your pup. Any form of Benadryl® that contains alcohol should also be avoided. If your pup needs liquid diphenhydramine, they will prescribe it and give it to you.

 How often can I give my dog Benadryl®?

As with any medication, only give your dog a dose of Benadryl® that’s been prescribed by your veterinarian. If you have questions, ask. Additionally, there are formulations that when combined with other medications become dangerous, such as Tylenol. Make sure that the Benadryl® tablets you give your pup contain only diphenhydramine and not alcohol or sodium.

A practical dose of Benadryl® is 1 mg per pound of your dog’s weight and should be given two to three times a day (every 8-12 hours). Reach out to your veterinarian if you have any questions or concerns.

 Side Effects of Benadryl® for Dogs

Benadryl® should have a few side effects at normal doses, such as drowsiness or unsteadiness. When you give your pet too much Benadryl®, they may show signs of:

  • Pronounced sedation or agitation
  • Severe unsteadiness
  • Disorientation
  • Increased or unusual aggression
  • Slowed breathing
  • Vomiting
  • Diarrhea
  • Seizures

How to Spot a Benadryl® Overdose

Your dog can experience a Benadryl® overdose if the dosage guidelines aren’t followed. The following are signs of a Benadryl® overdose:

  • Agitation
  • Excessive excitement
  • Seizures
  • Pronounced sedation
  • Diarrhea
  • Vomiting
  • Constipation
  • Abnormal blood pressure
  • Hypotension
  • Abnormal heart rate

Are there Alternatives to Giving a Dog Benadryl®?

While Benadryl® is over-the-counter and convenient, diphenhydramine has been around for some time. Continued research has helped to develop new treatments that can be more effective than Benadryl®.

Different types of treatments are the best way to manage a dog’s allergies, per the instructions of your trusted veterinarian. Medicated shampoos, supplements, and prescription medications can work together to reduce your dog’s allergies and allergic reactions. Prescription anti-anxiety medications combined with behavioral programs will do an overall better job than simply giving your pupper more Benadryl®.

If you have any questions, speak with your local trusted veterinarian. Paoli Vetcare has decades of experience helping pets and pet owners, and we are more than happy to answer any questions you might have about Benadryl® or other medications. There are many ways to keep your dog healthy and happy, and we want to work with you to provide your pet with the best treatments possible for a superior quality of life.

Dr. Erin Downes VMD

Dr. Erin Downes graduated valedictorian from the University of Pennsylvania School of Veterinary Medicine in 1992. She and her husband, Dr. Jay Rowan are the owners of Paoli Vetcare | Main Line Vet & Animal Hospital.