Is Benadryl Safe For Dogs?

When used properly, Benadryl, a common brand name for the drug diphenhydramine, is very safe for dogs. However, over the counter versions of Benadryl designed for humans often contains other medications like acetaminophen or pseudophedrine, which can be toxic for dogs.

If you're giving your dog Benadryl, its highly recommended that you purchase a 100% pure formulation designed to be safe for dogs (and cats). You can purchase generic Benadryl (Diphenhydramine) meant specifically for dogs here.

No drug is completely benign, so owners should consult with their veterinarians before giving this common antihistamine to their pets. They should also educate themselves about proper use of the drug, form and dosing, side effects and overdose symptoms.


In dogs, Benadryl is commonly used to treat the following conditions:

  • Vaccine reactions.
  • Insect stings and bites.
  • Some forms of allergic skin disease.
  • The inflammatory symptoms of mast cell tumors.
  • Reactions to blood transfusions.
  • Other allergic reactions.
  • Motion sickness.


Drugstores carry a variety of Benadryl products as well as generic products containing diphenhydramine.

Unfortunately, not all of these products are safe for dogs. Some contain other medications, such as acetaminophen or pseudoephedrine, which can be toxic to dogs.

Other formulations contain alcohol, which is not appropriate for use in dogs, and some children’s products contain artificial sweeteners or flavorings that are not safe for dogs.

Credit: Somecanuckchick

Owners should always check with their veterinarians before giving any drug to their dogs. When purchasing Benadryl or another antihistamine for use in dogs, owners should carefully read labels to make sure they are getting the product recommended by their veterinarians. You can order generic Benadryl designed specifically for dogs (and cats) here.


The usual dose of Benadryl for dogs (adult) is 2 to 4 milligrams per kilogram of body weight, which corresponds to a dose of 0.9 to 1.8 miligrams per pound of body weight, according to the Merck Veterinary Manual.

The actual dose for an individual dog can vary depending on the dog’s condition, history with the drug, other medications being given and any other health issues the animal has. Dog owners should consult their veterinarians for specific dosing instructions for their animals.


The most common side effects of Benadryl in dogs include the following:

  • Drooling.
  • Excitability.
  • Drowsiness.
  • Rapid breathing.
  • Rapid heart rate.
  • Depression.

Side effects usually occur within an hour of taking the medication and are typically mild. If a dog experiences severe side effects, the animal needs immediate veterinary care.


Benadryl is a very safe drug for dogs, and it is unlikely that an owner would deliberately give a dog enough of the drug to be dangerous. Because dogs often eat things they should not, however, accidental overdose does happen.

This almost always occurs when a dog gets into a box or bottle of Benadryl. For example, an article in the Journal of Veterinary Emergency and Critical Care describes the case of a young Labrador retriever that ate the equivalent of more than 16 times the maximum recommended dose of Benadryl and had to be hospitalized due to severe overdose symptoms.

Symptoms of a Benadryl overdose can range from moderate to severe and include the following:

  • Agitation.
  • Extreme drowsiness.
  • Aggression.
  • Abnormal heart rate.
  • Muscle tremors.
  • Increased body temperature.
  • Abnormal behavior.
  • Difficulty breathing.
  • Increased blood pressure.

Any owner who suspects his or her dog is suffering from a Benadryl overdose should contact a veterinarian immediately.

If the dog is having difficulty breathing, collapses, has seizures or develops other severe symptoms, the animal requires immediate emergency care.

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For more information on Benadryl and its use in dogs, see the following sites:

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