A cat that has a fever after taking Miao San Duo may be due to adverse reactions or allergic reactions. Some kittens with relatively weak constitutions will experience vomiting, diarrhea, poor spirits, etc. after taking Miao San Duo. This usually takes about a day. It will get better, but some cats will also have fever, red and swollen eyes, itching, shock, etc. This is an allergic reaction and needs to be sent to a pet hospital for treatment immediately, otherwise it will be life-threatening.