Dogs Can Take Some Common Allergy Medications: Vets Share Everything You Need to Know 

Have you ever taken your dog for a vet visit and, upon explaining that your pup suffers from allergies, been told you could give them Benadryl? It can be shocking at first to hear that an over-the-counter allergy medication for humans can also be given to dogs, but this is certainly not to say that every antihistamine is safe for Fido. It is critical not only to consult your veterinarian before giving any medication to your dog, but to carefully follow directions for appropriate dosages and ingredients.

Which antihistamines are safe to give a dog?

Veterinarians say Benadryl (diphenhydramine), Zyrtec (cetirizine) and Claritin (loratadine) can typically be safely administered to dogs to ease symptoms of environmental allergies as well as allergic reactions. For example, maybe your dog goes outside and their eyes or skin become irritated, or they’re stung or bitten by an insect and experience hives or swelling. Experts note, though, that Benadryl is only effective for temporary relief of mild to moderate allergies and reactions, and won’t have a significant impact on dogs with severe allergy symptoms. With proper doses and no added or harmful ingredients, unhealthy side effects have rarely appeared in dogs who have taken these medications.

Effectiveness of antihistamines in dogs

While generally safe to administer to your dog with your vet’s guidance, these medications are not long-term cures for severe allergies.

Grant Little, DVM, veterinary expert with JustAnswer, notes that these products only help reduce histamine release which is seen with acute allergic flare ups from pollen in the air, bee stings or similar issues. For dogs with chronic allergies who are scratching their skin or ears, these medications won’t provide sustainable relief.

“Zyrtec seemed to have the best response, but it was minimal in treating canine atopic dermatitis (the most common form of canine allergies) and even some studies showed that the placebo was better anecdotally than the treatment group according to the owners,” says Little. “I never recommend these medications as a blanket treatment for allergies.”

Symptoms like itchiness, red skin, sneezing and coughing usually signal the need for an actual long-term treatment plan, Little says.

How to safely administer antihistamines to dogs

1. Check the ingredients

After you have discussed giving antihistamines to your dog with your veterinarian, the next vital step is to check labels and confirm that the ingredient list does not include any added decongestants or pain relievers which can be harmful and potentially toxic to dogs.

“They are mixed in with some of the allergy medications (such as benadryl – D), and would be very problematic if given to your dog,” says Little.. “I do not recommend giving these over the counter medications. If this is accidentally given, you must seek out emergency care or call poison control to get clarifying steps on what to do next.”

2. Give the proper dose to your dog

Figuring out the appropriate dose of antihistamine depends on the dog’s weight. For Benadryl, for example, veterinarians typically recommended 1 mg. per pound of body weight every eight to twelve hours as needed.

Medications and ingredients your dog should never ingest

It’s important to note that antihistamines which can be given to canines are the exception and not the rule, as most over-the-counter human medications are not safe for dogs.

“Keep in mind that there are NO safe OTC medications that can be given to dogs for pain,” says Dr. Liza Cahn, veterinary contributor for Embrace Pet Insurance. “Tylenol, non-steroidal anti-inflammatories (such as Advil, Motrin, Aleve, etc), Aspirin, and cold/flu/allergy medications are especially dangerous. You also need to keep an eye out for other toxic ingredients that may be used in human medications, such as xylitol. This artificial sweetener causes a dangerous and potentially fatal drop in blood sugar in dogs.”

Dr. Cahn suggests contacting your vet or a pet poison hotline immediately (noting that there is a fee, generally around $85, for this service). Two options she recommends are ASPCA poison control and the pet poison helpline.

Symptoms of adverse reaction to medication in dogs

Another necessary step is to monitor your dog after giving them medication to ensure they don’t experience abnormal or dangerous side effects. The most common side effects from these medications in dogs are drowsiness and digestive issues including vomiting, diarrhea and loss of appetite. Other possible signs of an adverse reaction include drooling, incoordination, seizures, hives, swelling, difficulty breathing, jaundice, changes in urination and changes in behavior, says Dr. Cahn, and some medications can also have long-term consequences such as liver damage and gastrointestinal ulceration, which may not be immediately noticeable.