Cat Prescription and Non-Prescription Drugs to Avoid

There are many kinds of cat prescription and non-prescription medications that cause unnecessary negative side effects and are often considered to do more harm than good. Some of these drugs are simply outdated; newer, more effective drugs with fewer unwanted side effects have been invented to treat the same diseases that the now outdated drugs were created to treat. Others have long-term side effects that were not identified until after they were approved.

Never give your cat any drug that was not designed for use in felines. Some substances can be beneficial in one species, and can be used in medications for that species, but the same substance could be poisonous to a similar species, so a medicine that cures symptoms in you may only make the same symptoms worse in your cat.

Pain Relievers

You should definitely never give your cat Tylenol because it can quickly cause death, even at small doses. Tylenol contains acetaminophen, which can act as a mild pain reliever for humans, but is very toxic to felines. If you cat ingests just one regular-strength Tylenol pill, it could experience increased respiratory rate, overly-stimulated mucous membranes, hypothermia or tachycardia, while two or more pills can cause depression of the central nervous system, excessive vomiting, swelling, excessive salivation, diarrhea, coma, or possibly even death. Drugs containing acetylsalicylic acid and salicylate, such as aspirin and Pepto-Bismol, are also off-limits to cats, as they can cause vomiting, anorexia, lethargy, or death.

Theobromine and Caffeine

While theobromine, an alkaloid commonly found in chocolate and coffee beans, does not cause the same effects in humans as caffeine, the two chemicals are structurally similar and they cause basically the same effects in cats. Theobromine and caffeine have very strong effects in felines: in small doses, it over-stimulates the central nervous system, causing excitability, nervousness, and shaking or tremors, while in high doses, the chemicals can cause cats to go into a seizure, coma or cardiac failure, possibly leading to death.


Piroxicam is sometimes used in cats for the treatment of certain kinds of cancer, but it can cause extensive gastrointestinal irritation, including ulceration and nephrotoxicity in many cats, so it is generally only used if the cancer does not respond to other treatments. If your cat is taking piroxicam, make sure to give it plenty of fluids, as the side effects are much more likely to occur in dehydrated animals.

Treatment after a Cat Ingests Toxic Substance

For many drugs that are toxic to felines, there is no cure once the animal has eaten the chemical. The best you can do is take your cat to the veterinarian, where they can have their stomach pumped, and the remaining chemicals of that have not been absorbed by the cat's body can be removed. From there, you can only hope that not enough of the drug has been absorbed by the cat's body to cause permanent damage.

Just because a drug works well in humans does not mean it will be beneficial for cats. Never give your cat any medication that was designed for humans and not approved for use in cats. Always research or consult a veterinarian about the indications and possible side effects of any drug you decide to administer to your cat.