Grapes are toxic to cats and should be completely avoided. Although there are fewer documented cases compared to dogs, grapes can cause vomiting, diarrhea, lethargy, abdominal pain, decreased appetite, dehydration, and potentially kidney problems in cats. Even small amounts might pose a risk, and products containing grapes like raisins, grape juice, or trail mix should also be kept away from cats. If a cat eats grapes or shows symptoms like vomiting or lethargy, immediate veterinary attention is necessary. Additionally, grapes and grape stems can also be a choking hazard for cats.