What medicine for a cat vomiting yellow foamy liquid?

A cat vomiting yellow foamy liquid may be caused by parasites, prolonged hunger, infectious disease, or pancreatitis. If vomiting is not frequent, withhold food temporarily, then give the cat some glucose and probiotics to settle the stomach, and watch its condition.

Once vomiting stops, feed small frequent amounts of warm-water-softened kibble. If vomiting is frequent, or comes with fever, arched-back abdominal pain, reduced appetite, or lethargy, take the cat to a vet promptly to determine the cause before considering medication.