It is not illegal. Cyproheptadine hydrochloride, the effective component of Apetamin fattening agent, is easy to produce adverse reactions after taking it. This drug is a prescription drug in China and must be used under the guidance of a doctor. Do not take it by yourself, so it is not illegal to buy a fattening agent. As of 2022 10, China has never approved any kind of fattening drugs, and all the "fattening drugs" that users come into contact with are not regular drugs.