Can I Give My Dog Benadryl and If So, How Much?

Benadryl, also known by its generic name diphenhydramine, is one of the few over-the-counter drugs that veterinarians routinely have owners administer at home.  While it is generally well tolerated and has a wide safety margin, there are a few things owners should keep in mind before dosing it at home:

1. What is Benadryl used for?

Benadryl is an antihistamine, blocking the H-1 receptors on smooth muscle and blood vessels. Some of its most common indications are the treatment of environmental allergies, allergic reactions to insect bites or stings, and pre-treatment of vaccine reactions. It also has some efficacy in the prevention of motion sickness in dogs and as a mild sedative.

2. When should I not use Benadryl?

Benadryl is contraindicated with certain conditions, such as pets with glaucoma, high blood pressure, and cardiovascular disease. It’s always best to contact your veterinarian for guidance before administering any medication to your pet, including Benadryl.

3. How much Benadryl should I give?

The standard dosage for oral Benadryl is 1 mg per pound of body weight, given 2-3 times a day. Most drug store diphenhydramine tablets are 25 mg, which is the size used for a 25 pound dog. Always double check the dosage before giving an over the counter medication. In addition, many formulations are combined with other medications such as Tylenol so make sure Benadryl tablets contain only diphenhydramine.

4. When should I contact my veterinarian?

Oral Benadryl is considered a mild to moderately effective antihistamine. If a pet is having an acute allergic reaction with facial swelling or difficulty breathing, skip the oral medications and go straight to the vet. Many allergic diseases require a combination of allergy medicine for dogs and treatment of underlying infections; if your pet is not responding to their prescription pet medication, talk to your vet for other options.