The general method for treating external parasites in cats is to apply the medication to the skin on the neck and then massage it in to allow the medication to penetrate the skin. External parasite treatment for cats is usually done once a month, but once every one or two months during winter when parasites are less prevalent. Some parasites are zoonotic (human and cat infestations are shared), so it's important to regularly disinfect the area where your cat lives and the utensils it uses. Washing your hands after playing with your cat is also an effective way to prevent parasites from spreading. 
What to pay attention to when deworming cats:
1. Dosage of deworming medication for cats. Deworming medication is toxic, so it is essential to administer it according to the instructions, especially for domestically produced deworming medications. Always weigh your cat before administering the medication and calculate the dosage based on their weight. Sometimes there may be leftover medication; if you feel it's wasteful, you can give it to stray cats.
2. Deworming your cat should be done regularly, about once a month. Cats are the definitive host for many parasites. Depending on the type of parasite, some have a life cycle of half a month, while others only last a week. Therefore, deworming once a month is absolutely necessary.
3. Never use external parasite treatments that are added to bath water. Cats have a very special skin structure, and toxic substances can penetrate into their bodies through the skin. In addition, cats have a habit of licking their fur, so using such parasite medications can lead to poisoning and death in cats.
