How Much Benadryl Should I Give My Dog?

Posted by Stacey Venzel

Most of the time, if your dog needs medication, you'll need to take him to the vet, since most human medications aren't safe for pets. However, Benadryl can help to relieve some allergy symptoms in dogs and, when given at the correct dose, it's safe for dogs, too. Just as you'd keep Benadryl in your medicine cabinet for your own potential allergic reactions, it's a good medication to have on hand as a just-in-case for your dog.

Keep in mind that Benadryl is a temporary fix, and if your dog has an ongoing reaction or skin irritation, he'll need an appointment with the vet. If your dog is having a truly severe reaction, take him to the vet or at least give your vet's office a call before you give him Benadryl.

Determining the right Benadryl dose

Before you give your dog an antihistamine, make sure you have the right amount.

Like most medications, the given dose is based on the dog's body weight. The standard Benadryl dosage for dogs is one mg/pound of body weight.

Available over-the-counter, most Benadryl tablets are 25 mg each--but it is important to always check the label ( a children's Benadryl might be best for small dogs). Abiding by the one mg/pound dose, one 25 mg tablet would be the correct dose for a 25-pound dog. The dose can be repeated twice in the day.

How Benadryl is used in dogs

Benadryl, also known by its common name diphenhydramine, is an antihistamine. That means it is typically used for allergic reactions.

Benadryl Dosing

Skin conditions and allergies that cause itchiness, sensitivity, sneezing or a runny nose can sometimes be treated short term with Benadryl. Inflammation or swelling caused by bee stings, for example, is another use for Benadryl in dogs.

While Benadryl overdose in people typically results in drowsiness and muscle spasms, it can be toxic in dogs. Adverse side effects in dogs from too much Benadryl include vomiting or nausea and a rapid heartbeat.

If your dog is ever sick from riding in the car, you can also proactively try Benadryl as it may help with motion sickness as well as seasonal allergies. Dog owners should always talk to their vet about using anything over the counter even if it's being used proactively for motion sickness (as mentioned above)!

Safety issues and cautions with Benadryl 

Allergic reactions can also be dangerous, so use your best judgment to determine if the dog's symptoms warrant emergency care. It is always best to check with your pet's veterinarian before administering medication, especially if the animal has a medical history or is taking any other medications.

My dog Sherman was stung by a bee (or what we think was a bee) when he was digging a hole in the backyard. I dosed Benadryl proactively before I saw any signs of inflammation where the insect bite occurred. I made sure to watch for dry mouth, difficulty breathing, rapid breathing, hyperexcitability, urinary retention or drowsiness which are both common side effects of Benadryl. It's better to be safe than sorry but always important to make sure the dosage of Benadryl works ok for your dog and they don't have any adverse side effects or adverse reactions.

Staff note: Vets have been known to prescribe Benadryl for other health conditions besides allergies and motion sickness in dogs - in fact, it has been used to treat dogs with mast cell tumors.

Your vet may also need to administer your dog Benadryl under the skin with an injection which will work quickly rather than an oral dose so follow up with them either way especially if it's an emergency. Benadryl for dogs shouldn't be given casually!

READ MORE: 4 Essential Tips for Giving Your Pet Medication

Has Benadryl worked to help your pet? Tell us in the comments below.

WATCH NOW: Pets Lead to Good Health


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How Much Benadryl Should I Give My Dog?