Generally, cats need external parasite treatment every month and internal parasite treatment every three months. However, if a cat is anemic, thin, malnourished, sick, unhealthy, or has just been vaccinated, deworming is not recommended.
If your cat vomits or becomes lethargic after deworming, this is likely normal. You can give your cat probiotics to help ease the burden on its digestive system and allow it to recover gradually. It's recommended to consult a veterinarian about the specific deworming intervals, which should be adjusted based on your cat's health condition and living environment.
