Clumping litter itself isn't inherently bad for cats, but some cats may experience issues if they ingest it. For most cats, using clumping litter is safe as long as they don't eat it. However, kittens or cats that are prone to eating litter might face health problems if they consume clumping litter, as it can cause gastrointestinal blockages. Always monitor your cat's behavior and consult a vet if you have any concerns.