I think I can safely say that most people feel comfortable using over the counter (OTC) medications themselves and would consider giving them to their pets.
OTC medications are convenient because they can be purchased without a prescription from the veterinarian, they are widely available for purchase and often cost less than prescription drugs. When used as part of a comprehensive treatment plan that is developed based on your pet’s physical exam findings and diagnostic test results they often work well. Drugs like famotidine, omeprazole, RestoraLAX and certain antihistamines are dispensed regularly, but the safest way to use them is under the supervision of your veterinarian with an ongoing doctor/patient relationship.
The concern I have about OTC medication is that because they can be purchased without a prescription, they can be used to treat animals without an accurate diagnosis or weight. If used to treat the wrong disease, used at the wrong dose or given to a species that will not tolerate the medication at any dose (Tylenol toxicity in cats) then we can be doing more harm than good to our pets.
Sometimes OTC medications are pet specific drugs that cause problems because they are meant for dogs but are given to cats. Topical flea/tick medications containing permethrins kill cats. De-wormers are usually safe, but if given to pregnant or nursing pets, negative outcomes are more likely to occur. More often OTC medication errors occur with medication labelled for human usage. The safety studies, dosing recommendations and known side effects attributed to these drugs are based on adult dosing so trying to find a safe dose for a small cat or dog can be challenging. Using children’s medication makes dosing easier, but if flavoured with xylitol (sugar alcohol used to replace sugar for flavouring) it is toxic to pets. It can quickly cause hypoglycemia, seizures and death.
Commonly used OTC medications include NSAIDS like Aspirin, Ibuprofen and Naproxen. They help alleviate pain, so they are often given to older, arthritic pets. The concern is they have a very narrow dosing window and tend to cause more gastrointestinal irritation, GI ulcerations and potential kidney and liver failure than the NSAIDS prescribed by your veterinarian. Another commonly used OTC medication is the cough suppressant dextromethorphan (Robitussin DM, Benylin DM). People give this to their dogs to treat kennel cough. It may be helpful at the right dose but giving even a slightly high dose can cause agitation, hallucinations, trembling, vomiting and diarrhea. Now let us assume the dose of medication is correct and the weight of the animal is known. What else can go wrong? That coughing dog may not have kennel cough (wrong diagnosis). It could be heart disease, lung disease or pneumonia (just to name a few things that cause coughing). Even if the OTC medication does not harm the pet using it may delay getting to your veterinary hospital to get a correct and timely diagnosis so proper treatment can be started.
In closing, I want to reiterate that OTC medications are not always harmful to your pet. They have their place in treating many common diseases and conditions but OTC or not; they are still drugs. All medications have side effects, and all are potentially toxic to people and pets. My goal here is to urge you to see your veterinarian if your pet is not feeling well instead of reaching for an OTC treatment. As someone working in a veterinary hospital, I want to see pets get great medical care and treatment. Your veterinary team is trained to diagnose and treat your pet and educate you as an owner about the medications we prescribe. We can talk to you about potential side effects, expected outcomes of treatment and hopefully get your four-legged friend feeling better quickly. If you do decide to use an OTC medication, just remember that dogs and cats are not small people and they are more likely to have a negative outcome using OTC products than we might.
Written by: Dr. Pam MacKay, DVM