How do I prevent hairballs, and how should I use hairball supplements?

Quick answer

Cats swallow fur while grooming, and it clumps together in the stomach to form a 'hairball,' which they then vomit up. But vomiting too often, or a hairball that fails to pass, can be dangerous if it blocks the intestines. Daily brushing to remove loose fur is the fundamental solution — pair it with a fiber-rich hairball-control food or hairball supplement (like a laxative-type gel) to help it pass through naturally in the stool.