The Truth About Benadryl For Dogs

Read this before giving Benadryl to your pup❗

While you probably reach for the Benadryl any time your seasonal allergies kick in, you may have wondered if it’s OK for you to give a pill to your pup when she’s suffering from her own dog allergies.

The Dodo reached out to Dr. Michelle Burch, a veterinarian at Paramount Pet Health, and Dr. Brian Evans, a veterinarian and medical director at Dutch, to find out more about Benadryl for dogs.

Is Benadryl safe for dogs?

Benadryl (aka diphenhydramine), which is typically used by humans to help combat allergy symptoms, can also be used for dogs who have allergies under the guidance of your veterinarian.

“Benadryl can be very safe for dogs and is regularly given to treat a variety of allergic reactions,” Dr. Evans told The Dodo.

Some of the most common ailments that vets prescribe Benadryl for include:

  • Hives
  • Itchiness
  • Swelling and inflammation
  • Redness
  • Coughing
  • Sneezing

While generally Benadryl is perfectly safe for most dogs to take, there may be some situations (like medical issues — more on that below) when Benadryl wouldn’t be recommended for your pup.

“I recommend speaking with your veterinarian before administering to ensure your pet does not have an underlying disease or taking medication that may cause an adverse reaction,” Dr. Burch told The Dodo.

What exactly is diphenhydramine?

Diphenhydramine is an antihistamine. “The antihistamine will stabilize the H1 receptors, making them unresponsive to histamine, decreasing itching and reducing mild inflammation,” Dr. Burch said.

While diphenhydramine can help a dog who’s suffering from allergies, it should be used with caution in dogs with glaucoma, prostatic hypertrophy and urinary bladder obstruction, as it can make these medical issues worse.

What’s the Benadryl dosage for dogs?

When it comes to how much and how often to give your pup Benadryl, it’s best that you speak with your veterinarian on the appropriate dosing of Benadryl for your dog — however, there are some general rules you should be aware of.

“The most common dosage for dogs is 1 miligram per pound,” Dr. Burch said. So if you have a 25-pound dog, you should be able to give her 25 milligrams of Benadryl.

Additionally, Benadryl is most often given to dogs every 8–12 hours (or about three times per day).

Side effects of Benadryl in dogs

When taking Benadryl, it’s possible that your dog may experience some side effects (similar to how you might get sleepy when taking it yourself).

“The most common side effects of Benadryl are sedation, dry mouth and constipation,” Dr. Evans said. “However, some animals can have an opposite effect and become excited and/or agitated.”

Other common side effects of Benadryl include:

  • Incoordination
  • Behavioral changes
  • Pupil dilation
  • Increased heart rate
  • Urine retention

Rare side effects of Benadryl include:

  • Diarrhea
  • Vomiting
  • Changes to appetite

Benadryl overdose in dogs

While Benadryl is generally regarded as a safe drug for your pup, if too much is given — or your pet gets into a whole bottle — serious side effects can occur.

“Dogs who ingest a toxic amount of Benadryl may experience central nervous system, gastrointestinal, cardiovascular or cholinergic symptoms,” Dr. Burch said.

Central nervous system symptoms: sedation, agitation, hyperactivity, high body temperature, anxiety, aggression, incoordination, respiratory depression, coma and seizure

Gastrointestinal symptoms: vomiting and diarrhea

Cardiovascular symptoms: high heart rate and high or low blood pressure

Cholinergic symptoms: hallucinations, high blood pressure, high heart rate, cardiac arrhythmias, urine retention, dilated pupils, seizure and coma

“If you think your dog has ingested a toxic amount of Benadryl, I recommend contacting your primary veterinarian, emergency veterinarian, ASPCA Animal Poison Control or Pet Poison Helpline,” Dr. Burch said.

Generally, Benadryl is a great and effective tool to help your pup combat her allergies. Just make sure to consult with your veterinarian before giving her some.