The proper treatment for cat diarrhea depends on the underlying cause. Whether it's parasites, an allergic reaction, intestinal trouble or something else, it's important that you consult with an experienced vet regarding the health and treatment of your pet as soon as possible.
Before you can treat your cat's diarrhea, your vet will need to determine what's causing it so he can treat the underlying problem. For example, diarrhea can be caused by internal parasites, in which case your cat will need to take medication to kill those parasites. Diarrhea can be caused by a bacterial or viral infection, which might require antibiotics. Hyperthyroidism and inflammatory bowel disease also require medication.
Looking at Other Factors
A number of medications -- including antibiotics -- can cause diarrhea in cats. If your cat develops diarrhea after he starts taking medication to treat a condition, your vet might recommend switching to a different drug to see if that helps. Your cat could develop diarrhea if you suddenly switch to a new type or brand of food or if he develops an allergy or some sort of food intolerance you hadn't suspected.
Diarrhea in cats is often a sign of gastrointestinal problems, which is where probiotics come in. Probiotics are "good" bacteria that can help fix bacteria imbalance in the small intestine, as well as make the intestines healthier, increase the production of digestive enzymes and lower intestinal pH. Probiotics also might help to improve immune function. Your vet can recommend the right probiotic for your cat if he thinks taking these supplements might help solve the diarrhea problem.
Other Drugs Available
If the cause of diarrhea is connected to the gastrointestinal tract directly -- for example, if your cat is diagnosed with inflammatory bowel disease -- your vet might recommend a combination of immunosuppressive and anti-inflammatory drugs. Corticosteroids are an example of a commonly prescribed drug to treat inflammatory bowel disease in cats, although your vet can prescribe stronger drugs and sometimes combine them with antibiotics to achieve results faster.