Is Cystopteris fragilis toxic to cats?

Mildly. The ASPCA lists cystopteris fragilis as mildly toxic to cats — a chewing cat typically gets mouth irritation, drooling, and vomiting rather than a medical emergency, but it is still best kept out of reach. Cystopteris (bladder fern) is not individually listed in the ASPCA Toxic/Non-Toxic Plant database for cats, dogs, or horses, so its safety is unconfirmed. Many true ferns are non-toxic, but because this genus is unlisted, treat it with caution, discourage chewing, and verify with a vet before exposing pets.

Cystopteris (bladder fern) is not individually listed in the ASPCA Toxic/Non-Toxic Plant database for cats, dogs, or horses, so its safety is unconfirmed. Many true ferns are non-toxic, but because this genus is unlisted, treat it with caution, discourage chewing, and verify with a vet before exposing pets. Signs usually appear soon after chewing rather than hours later — watch for drooling, pawing at the mouth, vomiting, loss of appetite, or unusual lethargy after your cat has had access to cystopteris fragilis.

Stay calm. Remove any plant from your cat's mouth and take the plant away. Note how much was eaten and when, and do not induce vomiting unless told to. Call your vet or the ASPCA Animal Poison Control Center on (888) 426-4435 and follow their advice; a leaf or photo helps the vet treat it correctly.

The ASPCA classification Growli uses applies to both cats and dogs: Cystopteris fragilis is mildly toxic to dogs as well. See the full cystopteris fragilis pet-safety guide for both species.

For a similar look without the risk, see the best cats-safe plants list — every plant there is ASPCA non-toxic to cats and dogs.