Benadryl For Dogs: Dosage And Safety Information

Benadryl can be used for dogs, and the recommended dosage is typically about 1 milligrams per pound of body weight for a dog. Or in other words: 10 milligrams per dose (given 2 to 3 times a day) for dogs 30 lbs or smaller, 25 mg per dose for dogs which are between 30 to 50 lbs and 50 mg per dose for dogs 50 lbs or over.


“The world would be a nicer place if everybody had the ability to love as unconditionally as a dog.” — M. K. Clinton

While this is the general guide for dogs based on their size, it is recommended that you contact your veterinarian to get more information about the correct dosage as well as the safety information for your dog. While this is the short answer, to understand when and why you may want to give Benadryl to your dog, it’s important to be acquainted with Benadryl’s function and use.

What is Benadryl and How Does It Work?

Benadryl is the brand name for various antihistamines. Antihistamines are a class of drugs used to combat the effects of allergic reactions, such as hives, sneezing, nasal congestion, or swelling. The class of drugs is referred to as antihistamines because they counteract the activity of histamine receptors within the body.

Histamines are chemicals your body produces as a defense mechanism against allergens, things that could possibly harm you. The function of histamines is to kickstart a process that will remove the allergens from your body. This is done through various bodily functions such as creating tears, sneezing, or itching. What people refer to as allergies are often the overreaction of the body to compounds typically seen as harmless, like pet dander or pollen. Antihistamines are typically used to combat allergies by interrupting the reception of histamines in the body.

The skeletal structure of diphenhydramine. Photo: Public Domain

Antihistamines attempt to block, or reduce, the reception of histamines, which in turn helps decrease the severity of allergy symptoms. Allergy medicines can substantially reduce the manifestation of symptoms like watery eyes, running nose, rashes and swelling due to hay fever, dust, food allergies, and pet dander. However, there are limitations to what antihistamines can accomplish and they often can’t prevent every symptom you are suffering from.

Benadryl is simply one type of antihistamine, the brand name for the antihistamine known as diphenhydramine. In addition to the treatment of symptoms of allergies, diphenhydramine is sometimes used to treat vomiting, nausea, and dizziness. As with all medication, there are possible side effects to the use of Benadryl or other diphenhydramines. Drowsiness, dizziness, and dry mouth are the most common side effects.

Why Would You Give Your Dog Benadryl?

As previously mentioned, Benadryl is an antihistamine used to treat allergic reactions. This includes the allergic reactions your dog may have to certain chemical compounds. While most human medication isn’t fit to be consumed by dogs, diphenhydramine is a drug that works in dogs as well as in humans. Benadryl or other diphenhydramines can be used to treat the swelling your dog may experience from some insect stings or bites, as well as environmental allergies and motion sickness (such as those that occur during car rides or plane rides). It is frequently used to help minimize the side-effects of reactions to vaccines or other treatments.

“The more I learn about people, the more I like my dog.” — Mark Twain


You may wish to give your dog Benadryl if your dog is suffering from one of the following symptoms of an allergic reaction: a runny nose, watering eyes, redness of the eyes, sneezing, coughing, swelling, inflammation, coughing, hives, itching. Some dogs also suffer from anxiety (which may manifest itself during events like thunderstorms) and since Benadryl is a mild sedative, it may have a calming effect on them.

Administering Benadryl (Diphenhydramine)

The standard tablets of diphenhydramine bought in a drug store are typically around 25 milligrams. This would be the appropriate size for a 25-pound dog. Be sure to double-check the dosage before you give your dog any over the counter medication. (Be aware that some packages of diphenhydramine are combined with other medications, like Tylenol. Give your dog only tablets which contain diphenhydramine by itself.)

Photo: MabelAmber via Pixabay, CC0

When administering Benadryl, give your dog a small amount of the Benadryl at first, not the full dosage. As with the administration of any medication, closely observe your dog for the first few hours after the drug has been administered. This is to ensure that your dog doesn’t have a bad reaction to the medication, or that their allergic reaction continues to worsen. If your dog does not have any adverse reactions to a small dose of Benadryl, you will be safer giving them the full dose.

You may wish to ensure your dog has a full stomach before you give them a dose of diphenhydramine. Diphenhydramine often causes nausea, but having a full stomach before consuming the drug can help prevent this effect.

It is recommended that you avoid liquid diphenhydramine. Liquid diphenhydramine often comes in the form of gel caps, and it frequently has a high concentration of alcohol content, which is dangerous for dogs. Do not give Benadryl to puppies without consulting a veterinarian first. Puppies, much like baby humans, have delicate and still developing bodies that can’t tolerate many medications.

“Dogs have a way of finding the people who need them, filling an emptiness we don’t even know we have.” — Thom Jones

Don’t give your dog diphenhydramine without first consulting a veterinarian if your pet has certain conditions like cardiovascular disease, high blood pressure, and glaucoma. Be especially sure to contact a vet before administering Benadryl if your dog has one of the following conditions: angle-closure glaucoma, heart failure, allergic lung disease, prostatic hypertrophy, bladder neck obstruction, pregnancy, seizures. In general, it is good practice to contact your vet before you give your dog any medication.

Diphenhydramine is only effective in mild to moderate cases of an allergic reaction. If your dog is having a severe reaction to an allergen – either difficulty breathing or facial swelling – take your dog directly to the vet. You should also take your dog to the vet if your dog displays any signs of severe reactions to the Benadryl. While Benadryl is typically safe for your dog to consume, some dogs can have allergic reactions to the Benadryl itself or over-consume the drug. Signs of severe allergic reactions include seizures, rapid heart rate, constipation, agitation, and dilated pupils. Take your dog to the vet immediately if they display any signs of these reactions to Benadryl.



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