Easter lilies and other lilies can be toxic to cats, causing kidney failure and death. All parts of the lily can be toxic, and eating just one leaf can result in severe poisoning. After eating a portion of an Easter lily, a cat will generally vomit and become depressed within 2 hours. The vomiting may subside, but the cat will not eat and continue to become more depressed.
Contact your veterinarian immediately if you know or suspect your cat has eaten any part of an Easter lily. Your veterinarian will start treatment that includes causing the cat to vomit by giving an emetic, administering activated charcoal and a cathartic (stimulates bowel movements), and giving subcutaenous or intravenous fluids. A cat must be treated within 18 hours of ingesting the plant, or the damage to the kidneys will be irreversible.
Other lilies which belong to this same plant species and are also toxic include tiger lilies, rubrum or Japanese showy lilies, and various day lilies. Many other bulb plants are also poisonous such as daffodils and hyacinths.