Cats can eat vitamin C, but not human vitamin C. The amount of vitamin C a cat needs differs from a human's, so the dosage cannot be accurately determined, and overfeeding can be harmful. If you want to supplement your cat's vitamin C intake, it's recommended to buy cat-specific vitamin tablets from a reputable pet store. Furthermore, in feline medicine, vitamin C is primarily used to treat methemoglobinemia caused by acetaminophen poisoning. 
Why it's not recommended to give cats vitamin C:
1. Cats can synthesize some vitamin C on their own, so they rarely suffer from vitamin C deficiency.
2. Vitamin C has an unpleasant taste and is quite irritating to the cat's oral mucosa, making it resistant to feeding. Forced feeding may cause a decrease in appetite.
