Not all lily species are poisonous to cats. Calla, Peace and Peruvian lilies are not ‘true’ lilies, and while they may irritate the mouth if eaten, and cause pain, salivation and facial swelling, they do not cause the serious kidney signs associated with true lily poisoning.
True lilies include Easter, Rubrum, Asiatic, Day, Stargazer, Japanese and Tiger lilies. These lilies are poisonous to cats and this includes their petals, leaves, pollen and even water from the vase. Lilies can drop a lot of pollen, and cats can walk through this or brush against the flowers, getting pollen on their coat. One of the most common ways for cats to ingest lilies is as they clean pollen from their fur.
If you do receive lilies, cutting out the stamens can reduce the pollen drop and therefore the risk. However, as all parts of the lily are toxic and even lilies which are not ‘true’ lilies can cause discomfort, not bringing lilies into a house with cats is considered the safest and recommended course of action.