Many dog owners medicate their dogs using medication, such as aspirin and diarrhea medication for humans. It is not uncommon for people to then assume that because these medications are safe for dogs that they are also safe for cats. To be perfectly clear, many medications that are safe for dogs, are not safe for cats, and should never be used on cats without proper veterinarian instruction.

Acetaminophen

An example would be Tylenol. Used as pain killers, these are toxic to cats. Acetaminophen can damage the red blood cells, even one pill is enough to do serious damage. It should be considered highly toxic to cats.

NSAIDs

NSAID stands for non-steroidal anti-inflammatory drug. Examples of this would be Aspirin, Advil, Aleve, and Motrin. These are often used to relive pain, or control a fever. In cats NSAIDs can cause stomach ulcers and kidney failure.

Sleeping Pills

These will not necessarily make a cat sleepy, they can make the heart race and may cause liver failure.

Anti-Depressants

Giving your cat an anti-depressant may not cheer your cat up, it could kill your cat. Veterinarians will sometimes prescribe them, under a specific dosage, but more than that could be fatal. Effexor tastes particularly good to cats however it can be poisonous to a cat.

Diarrhea Medication

At one time some diarrhea medicines, such as Kaopectate, were safe for cats, however currently none are. Many diarrhea medications have changed their ingredients and now include bismuth subsalicylate, which is toxic to cats.

Toothpaste

While not a medication as such, it should be noted that human toothpaste contains ingredients that are toxic to both cats, and dogs, as such you should stick to only using a toothpaste made for pets.

Shampoo

Again not a medication, however using human shampoo when bathing a cat can dry out a cat's skin and fur. If you must use human shampoo use baby shampoo and rinse well.

Note – If your pet has accidentally swallowed any pill for humans, contact your veterinarian immediately. In the United States and Canada there is a Pet Poison Hotline at 1-800-213-6680. All in all it is generally not considered a good idea to offer medication to a pet without talking to your veterinarian.

Keep all your medication out of reach of your cat, never leave a pill on the counter where a playful cat could find it (and lick it), and do not store medication in a plastic bag, cats often chew plastic bags and could swallow loose pills.