If your cat is vomiting hair, try giving it hairball medicine or changing its diet to a hairball remedy food. This can help the hair break up and pass through the digestive system without upsetting the stomach. Often, this is all it takes to stop frequent vomiting.
If your cat is vomiting but does not appear to have hair or other items that cannot be digested in its vomit, it may be a sign of a health problem or disease such as kidney or liver disease, feline panleukopenia, nervous system disorder, inflammatory bowel disease or other condition.
Pay attention to how often your cat vomits, and if it appears to be related to eating or other activities. This will help your vet pinpoint the cause of the vomiting. If your cat continues to vomit, you will need to take him to the vet. If he is vomiting blood, the situation is urgent and he should be seen immediately.
Unless you are sure about the cause of vomiting and it is not serious, you should take your cat to the vet so proper treatment can begin and your cat can find relief. If the cause is infection, treatment can make a difference almost immediately, so the sooner you get him to the vet, the sooner he can feel better.