It's National Indoor Plant Week. Across a Decade of Poison-Control Calls, the Single Most Common Thing a Cat Got Into Was a Lily.

National Indoor Plant Week runs the third week of September, which this year started Monday. [1] It is a good week to take stock of what is on the windowsill — and a better one if you live with a cat.

The plant that shows up more than any other

Between 2005 and 2014, the ASPCA Animal Poison Control Center logged 241,253 calls involving 253,138 animals. [2] For cats, plants and mushrooms accounted for 28.27% of exposures, second only to human medications. [2]

And when the researchers ranked individual substances instead of broad categories, the most common single exposure for cats across that entire decade was not chocolate, not a cleaning product, and not one of the trendy houseplants. It was Lilium — true lilies — at 5.86% of cat calls. [2]

Plants and fungi still accounted for 7.5% of the more than 376,000 cases ASPCA Poison Control handled in 2025. [3]

Nearly half of exposed cats showed kidney injury

A 2025 study from the University of Pennsylvania School of Veterinary Medicine followed 112 cats treated after lily exposure. Acute kidney injury developed in 46.9% of the cats hospitalized on intravenous fluids and 43.8% of those treated as outpatients with fluids under the skin. [4]

The study's headline finding was reassuring in one sense: outpatient treatment produced comparable kidney outcomes, which matters for families without access to a 24-hour hospital. Survival was 100% in the inpatient group and 87.5% in the outpatient group, and the authors reported a higher overall rate of kidney injury than had been previously documented. [5]

Every part of a true lily is toxic to a cat — petals, leaves, stem, pollen, and the water in the vase. Cats have been poisoned by drinking vase water or by grooming pollen off their own fur. [6] Treatment started within roughly 18 hours is what prevents the kidney damage; when treatment is delayed, the outcome is often fatal. [6]

The genera worth memorizing are short: Lilium (Easter, Asiatic, tiger, stargazer) and Hemerocallis (daylilies). Convallaria, lily of the valley, is a separate problem — it contains cardiac glycosides, so the concern is stomach upset and an irregular heartbeat rather than the kidneys. [6]

The popular houseplants are a milder story

Several plants sold under the word "lily" are not lilies at all. The peace lily (Spathiphyllum) and the Peruvian lily (Alstroemeria) both fall outside the dangerous genera. Peace lilies contain insoluble calcium oxalate crystals, which cause immediate mouth pain, drooling and vomiting — genuinely unpleasant, but serious injury is very rare. [6] Peruvian lilies may cause stomach upset without being life-threatening. [6]

That same calcium oxalate mechanism covers most of the plants that fill a fall houseplant order: pothos, philodendron, monstera, dieffenbachia, ZZ plant. A pet who chews one is usually in pain rather than in danger, and the pain itself tends to stop the chewing quickly. They are still worth putting out of reach, and still worth a call to your vet — but they may not warrant the alarm a true lily does.

For dogs, the plant to know is the sago palm

Sago palm shows up in garden centers as a tidy little indoor palm, and it is in a different category entirely. In a study of 130 dogs published in the Australian Veterinary Journal in 2020, 107 dogs — 82.3% — developed clinical signs, and overall mortality was 12.3%: two dogs died and 14 were euthanized. [7]

Two findings from that paper are worth carrying around. Activated charcoal reduced the odds of mortality by 82%, which is an argument for going in early rather than waiting to see how the evening goes. And a low platelet count, along with elevated ALT on the first bloodwork, marked the dogs who did worst. [7]

What to do this week

• Start with the cut flowers, not the pots. The dangerous lilies mostly arrive as bouquets. Check a new arrangement for Lilium and Hemerocallis before it goes on a table, and remember the vase water counts.
• If a cat has any contact with a true lily, treat it as time-sensitive. Pollen on the coat, a chewed leaf, a sip from the vase. The 18-hour window is the whole reason to call before symptoms appear. [6]
• Photograph the plant tag when you bring something new home. A name is far more useful to a vet at 10pm than a description of a green leaf.
• Keep the number somewhere findable. ASPCA Animal Poison Control Center: (888) 426-4435. [3]

Most houseplants are fine, and the ones that are not tend to be specific and identifiable. Indoor Plant Week is as good an excuse as any to walk the room once and know which is which.

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Sources

1. National Day Calendar, "National Indoor Plant Week — Third Week in September"
2. Swirski AL, et al., "Companion animal exposures to potentially poisonous substances reported to a national poison control center in the United States in 2005 through 2014", Journal of the American Veterinary Medical Association, 2020
3. ASPCA, "The Top 10 Toxins of 2025"
4. dvm360, "Outpatient treatment for lily toxicity in cats"
5. Veterinary Practice News, "Outpatient treatment may be viable for lily toxicity in cats, study reveals" — reporting on Prevalence of acute kidney injury and outcome in cats treated as inpatients versus outpatients following lily exposure, JAVMA, 2025
6. ASPCA, "Which Lilies Are Toxic to Pets?"
7. "The characterization of cycad palm toxicosis and treatment effects in 130 dogs", Australian Veterinary Journal, 2020