When your cat is throwing up, it's usually a yellowish-greenish bile or liquid. This type of vomit is often clear and has a sour smell. If your cat is throwing up too much or if the color is turning darker, it could be a sign that their stomach is upset due to parasites or a more serious health issue. You should take your cat to the vet as soon as possible. Another type of unhealthy cat throw up is a thick, pasty substance that looks like coffee grounds. This type of vomit is usually caused by bleeding in the stomach or intestines, and it's important to take your cat to the vet right away. You may also notice that your cat is throwing up food in chunks. This can happen if your cat is having trouble digesting food, or they may be eating too fast. If your cat is throwing up food chunks, it's a sign that they may be having an issue with their digestive system and you should take them to the vet. Finally, if your cat is throwing up blood, this is a serious sign of illness and you should take them to the vet immediately. Blood in the vomit can be a sign of an ulcer, a tumor, or another serious health issue.