Plants Safe for Cats: Toxic Plants in the House and Garden

Curiosity killed the cat, but the biggest danger to a beloved pet could in fact be the seemingly benign plants lurking in a home.

Most cats are fastidious creatures, and because they tend to be careful about what they eat, poisoning is generally rare, according to the International Cat Care Organization.

However, to be on the safe side, here is a list of the most common plants toxic to cats to avoid growing in your home or garden.

cat in grass
A domestic tabby cat sits in the grass surrounded by pink flowers. C P George/Getty Images

Are lilies poisonous to cats?

Lily toxicity is particularly dangerous for cats and can result in death. The entire lily plant is toxic: from the stem to the flowers, leaves, bulb, pollen and even the water in the vase, warns American Kennel Club Chief Veterinary expert, Dr. Jerry Klein.

"Signs may start with drooling and vomiting, painful abdomen, abnormal heart rates but can lead to serious complete urine shutdown production, which is usually fatal, within 48 hours," Klein told Newsweek.

Consumption most commonly occurs when pollen that has fallen from the plant is licked off the cat's fur during grooming, according to U.K. charity Cats Protection.

Klein concurred, explaining that flower arrangements are the most common cause of lily exposure to cats.

"Every part of the lily is extremely dangerous for cats," cat behavior expert and author Pam Johnson-Bennett told Newsweek. "Even coming in contact with the pollen can cause acute kidney injury."

There are many varieties of lilies, but the most dangerous and potentially fatal are true lilies. These include tiger, day, Asiatic, Easter and Japanese show lilies.

Bearded sword lily
A bearded sword lily blooms in a field. Lily toxicity is particularly dangerous for cats and can result in death. TF-Images/Getty Images

Tulip and hyacinth

These colorful flowers are harmful to many pets—mainly because of their bulbs, which are toxic if ingested.

"These plants usually contain specific toxins throughout the plant (glycosides), but the compounds tend to have much more concentrated alkaloids in the bulb," Klein told Newsweek.

"Glycoside toxicity is usually exhibited with gastrointestinal signs such as drooling, vomiting and diarrhea but can range to neurologic and cardiac changes in extreme cases."

Tulips and hyacinths also contain the alkaloid Tuliposide A, Klein added.

As the bulbs are more commonly dug up by curious dogs in the back garden, these flowers usually pose less of a risk to pet cats.

Tulips and hyacinths
Tulips and grape hyacinths seen at a floral display in Turkey. The bulbs in particular are poisonous to cats if eaten. Tim Graham/Getty Images

Oleander

This popular ornamental garden plant is considered to be toxic to cats as it contains cardiac glycosides—organic compounds that have the potential to cause gastrointestinal tract irritation, abnormal heart function, hypothermia and even death.

Cardiac glycosides inhibit the sodium/potassium pump in cells, causing hyperkalemia (high potassium) and increasing intracellular calcium, which can lead to cardiac irritability and arrhythmias, according to the ASPCA Animal Poison Control Center. Glycosides also decrease sympathetic tone and increase vagal tone, resulting in bradycardia (slow heart rate) and heart block.

Symptoms to look out for include vomiting, diarrhea, bradycardia or tachycardia (fast heart rate), blood pressure changes or lethargy.

oleander
An oleander bush in a California garden. This popular ornamental plant is considered toxic to cats as it contains cardiac glycosides. George Rose/Getty Images

Autumn crocus

These pretty plants contain colchicine, which is extremely toxic to cats. It can cause multiple organ damage such as kidney and liver damage, severe and bloody vomiting, diarrhea and respiratory failure, the ASPCA notes.

Symptoms might be delayed for several days, so it is important to seek veterinary attention if you suspect your cat has ingested the plant.

saffron flower crocus sativus
These pretty plants contain colchicine, which is extremely toxic. Patrizia Piccini/Getty Images

Iris

The iris can cause tissue irritation when consumed or come into contact with. Ingestion can result in drooling, vomiting, diarrhea and lethargy, according to the Pet Poison helpline.

Iris Flower
A yellow flag iris in bloom in Oxfordshire, U.K. The iris can cause tissue irritation when consumed. Tim Graham/Getty Images

Peace lily

This houseplant is found in many homes and offices. Despite its name, it is not actually in the Liliaceae family.

"Peace Lilies contain calcium oxalate crystals which cause burning and irritation of the mucous membranes of the mouth, the esophagus and the stomach leading to salivation, vomiting, diarrhea," Klein told Newsweek.

Signs of toxicity include burning and irritation of the mouth, tongue and lips, excessive drooling, vomiting and trouble swallowing.

Peace Lily
A peace lily seen in the Kyoto botanical garden in Japan. Eric Lafforgue/Getty Images

Rhododendron

The entire genus of this plant species is extremely dangerous to most pets, including cats. Eating even a few leaves can cause vomiting, diarrhea, drooling, paralysis, shock, coma and death, the American Kennel Club warns.

"Azaleas and Rhododendrons contain a neurotoxin called Grayantonin, a toxin that affects the body's sodium channels which can then affect muscle tissue of the heart and skeletal muscles," Klein told Newsweek. "All parts of the plant can be toxic and even small ingestions of the plant are dangerous to cats."

Ingesting as little as 0.2 per cent of an animal's body weight can result in poisoning, according to the Pet Poison helpline. With treatment, prognosis is fair.

The Purdue University College of Veterinary Medicine states: "These ornamental shrubs aren't commonly nibbled on but they can cause fatal heart problems in dogs, cats and pet birds."

Azaleas, in the same family as rhododendrons, are just as dangerous.

rhododendrons
A rhododendron bush. The entire genus of this plant species is extremely dangerous to most pets. Tim Graham/Getty Images

Foxglove

Although beautiful with their delicate trumpet-like blossoms, all parts of these flowers— from the seeds to the petals—are extremely toxic to cats and to humans. Ingestion can cause cardiac failure and even death, the Pet Poison Helpline warns.

The plant contains cardiac glycosides such as digitoxin. These naturally occurring poisons affect the heart.

Foxglove flower
Foxglove flowers grow in Northallerton, England. All parts of these delicate flowers - from the seeds to the petals - are extremely toxic. Ian Forsyth/Getty Images

Castor bean

This plant contains ricin, one of the most poisonous naturally occurring substances known. The seeds from the castor bean, ricinus communis, are particularly harmful to cats, the Department of Animal Science at Cornell University warns.

Luckily, the castor bean is not so common in residential gardens and is more commonly found in parks and other outside areas.

castor bean
The seeds from the castor bean plant, ricinus communis, are poisonous to cats. AARON MASCHO/Getty Images

Cat owners should consult the comprehensive list of potentially toxic plants put out by the ASPCA Animal Poison Control, Johnson-Bennett told Newsweek.

If you allow your cat outdoors or have cats who come into your yard, check the ASPCA list before planning your garden, she suggests.

"When it comes to having indoor cats, the safest route is to make sure there is no access to any plant," she added. "Even plants not listed as poisonous may still cause gastrointestinal upset if chewed."

Himalayan cat
A purebred Himalayan cat sits in a garden. Viviane Moos/Getty Images