Many things are toxic to cats. Many of the medications and compounds that are safe for people and even dogs are poisonous to cats. The following is a partial list of items that may be around your home that many people don't realize are toxic to cats. There are many other things that are also toxic.
Acetaminophen - This popular human pain reliever can cause life-threatening damage to the liver and blood of a cat.
Benzocaine - This is a topical anesthetic found in many first aid creams, sprays and gels, such as Orajel. It can cause dangerous damage to red blood cells even if applied topically.
Lily Plants - There are different types of plants termed lilies. True lilies, such as Easter lilies, tiger lilies, Asiatic hybrid lilies, and daylilies are deadly to cats. The Lily of the valley plant is also toxic. Others, such as calla lilies and peace lilies are not true lilies, and ingestion only results in mild gastrointestinal upset. If you suspect your cat ingested part of a lily plant, it is important to be able to tell your veterinarian exactly what kind of lily it was.
Phosphate enemas - People will sometimes try to treat a cat they feel to be constipated with an enema made for children, such as a Fleet Enema. Many of these products contain phosphate which when given in this fashion can have a life-threatening toxic effect.
Kaopectate, Pepto-Bismol and Aspirin - These products all contain salicylate that can be toxic to cats.
Meloxicam - You are likely to see mixed and confusing reports about this pain reliever, which is still often used in cats. Careful and correct dosing and administration of this product is often effective in controlling pain in cats. There are reports of toxic events also. Do not give Meloxicam to your cat unless you have received precise instructions from your veterinarian.