If a cat bites a flea, you can apply medicine with anti-inflammatory and swelling ingredients, such as green ointment, Fengyoujing, etc. It is best to choose an ointment with milder ingredients to avoid irritating the affected area. At the same time, the cat should be dewormed to avoid recurrence. If the cat is bitten by fleas, it is usually best to deworm the cat once a month to avoid being infected with parasites. You can use special flea-killing drugs for the cat. If there are many fleas, you can give the cat a medicated bath.