Although an isolated cough every now and then is likely perfectly normal, cats do develop medical conditions that result in coughing, according to VCA Animal Hospitals. If you notice your cat coughs with a wet sound or he produces phlegm or sputum, or the coughing is severe or lasts for more than a few days, VCA recommends seeking veterinary assistance.
Coughing is often the result of inflammation, which occurs with a variety of health conditions—such as upper respiratory infections, parasites like heartworms, asthma or bronchitis and even lung tumors. Your vet will most likely need to perform bloodwork as well as chest radiographs (x-rays) to determine the cause of coughing in your cat.
When your cat is coughing or presenting with clinical signs of illness, the best plan is to take your sick cat to a veterinary hospital to be diagnosed and treated.