Can Human Allergy Medication Be Harmful for Pets? Our Experts Explain!

April 12, 2024


While changes in seasons are often welcomed, they can also bring on the all too familiar ‘allergy symptoms’ for some people. There are many kinds of medications, both over the counter and prescription, that can be used for allergy treatment, but it is important to exercise caution as there can be toxicity concerns for pets associated with common allergy medications. When purchasing over the counter medications, pay close attention to the formulations, as there can be additional active and inactive ingredients of concern for pets that are easy to overlook. To help you out, our experts at the ASPCA Animal Poison Control Center (APCC) take a look at some of the most common allergy treatments.

Antihistamines: When pets ingest a large dose of single-ingredient antihistamines (examples: cetirizine, diphenhydramine), the most common symptoms seen are lethargy, gastrointestinal upset and unsteadiness when walking. Antihistamines can also come in combination products that include decongestants and pet parents will often unknowingly purchase these combo antihistamines without realizing (example: pseudoephedrine). Pet exposures to some decongestants can be serious causing agitation, restless behavior, elevated heart rate and sometimes even tremors/seizures. Sometimes over the counter (OTC) antihistamines are recommended by veterinarians but always be sure to administer medications to your pet only under the direct supervision of a veterinary professional.

Cough Drops: Generally, pet exposures to cough drops tend not to be as serious as exposures to other OTC medications, however, there are a few ingredients to be aware of. Xylitol is a sugar alcohol that is sometimes used in cough drops. When dogs ingest xylitol, they can be at risk for gastrointestinal upset, low blood sugar and liver damage, which can be life-threatening. Also be mindful of cough drops that have anesthetic or ‘numbing’ properties from added medications (example: benzocaine), as these can affect the cardiac and respiratory systems when ingested by pets.

Decongestant Nasal Sprays/Redness Relief Eye Drops: Some nasal sprays and eye drops contain medications such as oxymetazoline, xylometazoline, tetrahydrozoline and naphazoline. These are often marketed to help treat ‘stuffy nose’ and ‘red eyes’ as they function to constrict local blood vessels, decreasing congestion and redness. When ingested by pets, these ingredients are rapidly absorbed and can cause vomiting, weakness, panting, agitation, low heart rate and low blood pressure, even in very small quantities.

Cold/Flu Medications: Cold/flu medications are commonly used by people to treat allergy symptoms. The formulations and available options for cold/flu medications are variable and numerous, but can often include mixtures of acetaminophen, ibuprofen, phenylephrine, pseudoephedrine, dextromethorphan, diphenhydramine and doxylamine. The risks vary based on the product but can include vomiting and stomach ulcers, changes in heart rate and blood pressure, kidney or liver injury and potentially neurologic signs.

Be sure to keep these items out of paw’s reach, and if administering allergy medications to your pet, always be sure to do so only under the direct supervision of your veterinarian.

If you have any reason to suspect your pet has ingested something toxic, please contact your veterinarian or the ASPCA Animal Poison Control Center’s 24-hour hotline at (888) 426-4435.