It's hard to narrow down which plants are toxic to cats since there are so many!
Here is a link to the complete list.
Common house plants that are toxic to cats:
Mildly Toxic Plants to Cats:
"Here are some of the most common plants poisonous to cats with mild symptoms: Philodendron, Pothos, Dieffenbachia, Peace lily, Poinsettia – Whether it comes from chewing on or ingesting the plants, all of these can lead to mouth and throat irritation, drooling and vomiting. Ficus and Snake (Mother-in-laws tongue) plants can result in vomiting and diarrhea, while Dracaena (corn plant) may cause vomiting, drooling, and staggering. Jade carries the same symptoms in addition to depression. Aloe plants can result in vomiting, diarrhea, lack of appetite, and staggering. Did you know that catnip can be mildly toxic too? While it’s normal for cats to appear “drunk” or somewhat “wild” when nibbling on the plant, too much within a short time can also result in vomiting and diarrhea."
Moderately Poisonous Plants for Cats:
"Ivy can cause vomiting, diarrhea, drooling, breathing difficulty, fever and muscle weakness. Azalea and rhododendrons can cause vomiting, diarrhea, hyper salivation, weakness, depression of the central nervous system and, in severe cases, death. Holly shrubs may result in digestive upset and nervous system depression. Norfolk pine causes vomiting, depression, pale gums and low body temperature. Euphorbia (spurge) plants result in mild to moderate digestive upset and excessive salivation."
Severely Toxic Plants to Cats:
"With exception to peace lily and calla lily, all other lily varieties are major threats to cats, causing kidney failure and death. It takes only a small amount to result in poisoning. Hydrangea shrubs contain a toxin similar to cyanide and can quickly lead to oxygen deprivation and death. All parts of sago palm are considered poisonous, with the seeds (nuts) being the most toxic part of the plant. Ingestion results in acute gastrointestinal symptoms, tremors and severe liver failure. Oleander, even in small amounts, can kill your cat. All parts are highly toxic, resulting in digestive problems, vomiting and diarrhea, irregular heartbeat, depression and death. Mistletoe can also lead to death. Other symptoms include digestive irritation, low heart rate and temperature, breathing difficulty, staggering, excess thirst, seizures and coma. In small doses, even a couple bites, the skunk cabbage plant can cause burning and swelling of the mouth and a choking sensation. Eating large portions of the leaves can, in extreme cases, be fatal. With any of these above severely poisonous plants for cats, don’t wait for major symptoms to appear. Take your cat to the vet, along with the plant (if possible) as soon as you can. Also, keep in mind that symptoms will vary from cat to cat, depending on their size and the parts or quantities of the plant ingested."
Common vegetable plants that are toxic to cats:
The green parts of Rhubarb plants, Tomato plants, Potato plants, and Zucchini Squash plant are toxic to humans, and all other animals.
Varieties of the Onion family including, garlic, chives, and leeks are toxic to animals.
Common herbs that are toxic to cats:
Spanish thyme and spring parsley are toxic to cats. Regular varieties of thyme and parsley are harmless to cats.
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