All parts of true lilies are acutely toxic to cats — even small exposures can cause fatal kidney failure

Which plants are affected

The most dangerous lilies are members of the genus Lilium and Hemerocallis:

Sources: ASPCA Toxic Plant Database and Cornell Feline Health Center.

Why lilies are so dangerous

The exact toxic compound in Lilium and Hemerocallis species has not been fully characterised, but its effect on cats is well-documented: it causes acute tubular necrosis — the death of cells in the kidney tubules — leading to rapid kidney failure. Remarkably, even tiny exposures can trigger this response. Licking pollen off fur after brushing against a lily is sufficient. Drinking water from a vase containing cut lilies is sufficient.

Dogs appear to be unaffected by these specific compounds. The toxicity is specific to cats (and some other obligate carnivores). It does not respond to antidotes — the only treatment is decontamination (inducing vomiting, activated charcoal) followed by aggressive IV fluid therapy to support kidney function. The sooner treatment begins, the better the prognosis. After 18 hours without treatment, the prognosis is poor.

Keeping lilies out of the home

The safest approach is to not bring Lilium or Hemerocallis species into a home where cats live. This includes cut flower arrangements — a single bouquet on a dining table is accessible to most cats. If you receive lilies as a gift, keep them outside, give them away, or discard them.

Florists and flower delivery services do not routinely label bouquets for pet safety. If you order flowers for a cat owner, request that lilies be excluded. Many UK florists now offer lily-free alternatives on request.