Cats can take multivitamins for a long time, but they should not use too much. It is best to buy multivitamins specially designed for cats and feed them according to the instructions to avoid improper dosage control. If a cat consumes excessive amounts of vitamins, it may develop symptoms such as vitamin poisoning, skeletal dysplasia, tooth loss, gastrointestinal dysfunction, and loss of appetite, and needs to stop taking vitamins immediately.