The diarrhea should then clear up. It if doesn't, look for a cause other than dietary intolerance. One of the most common foreign bodies cats ingest is their own fur. Hairballs, or trichobezoars, are made up of loose fur, which the cat swallows as it grooms. Either the fur travels from the cat's stomach through its intestines and out of its rectum during defecation, or it irritates the lining of the cat's stomach to such a degree that the cat vomits up the ticklish sausage-shaped nuisance.
Occasional hairballs are nothing to be concerned about.
But to reduce the frequency of regurgitated hairballs, you can regularly comb your cat's coat to remove loose hair. Longhaired cats and cats with thick coats particularly benefit from regular combing. Most hair will pass in cats. It is our feeling that if hair continually lodges in the stomach, there may be something wrong with the stomach and its connection to the small intestine. This may require some investigation as to the underlying cause, namely endoscopy.