If you want a weight-loss drug, get a prescription at a hospital; don't buy from online shops that ship without one

Moderate value
Evidence B
Buys life
Costs a little
Takes some hours
No willpower

In plain words

Prescription drugs must be sold with a prescription, and when sold online there must also be a real prescription and real-name registration. A shop that asks no questions, wants no prescription and ships as soon as you order is either not selling the drug it says or is breaking the rules. If something goes wrong, no one answers for your dose and your contraindications. A registration fee of a few dozen CNY gets a doctor to take care of that step for you.

Cost: One registration, plus a trip there and back. A few dozen CNY and half a day.
What you get: The Measures for the Supervision and Administration of Quality of Drug Distribution and Use (《药品经营和使用质量监督管理办法》) provide that retail drug businesses must follow the system of separate management for prescription and over-the-counter drugs. This system divides drugs into two classes, one that must be bought with a doctor's prescription and one you can buy yourself. A pharmacy must sell prescription drugs only against a prescription, as required, and keep the prescription for no less than five years. When the pharmacist or other pharmacy technical staff are not on duty, a sign must say so, and prescription drugs may not be sold without their review. Prescription drugs may not be displayed on open shelves where customers take them themselves. Article 9 of the Measures for the Supervision and Administration of Online Drug Sales (《药品网络销售监督管理办法》) provides that when prescription drugs are sold to individuals online, the source of the prescription must be genuine and reliable and real-name registration must be used. Article 10 requires risk warnings to be prominently displayed on every drug display page. Before the prescription passes review, the package insert may not be shown and no purchase service may be provided; if the prescription hasn't passed, the page should not even offer a buy button. Article 8 provides that drugs under special state control may not be sold online. These include vaccines, blood products, narcotic drugs, psychotropic drugs, toxic drugs for medical use, radioactive drugs and drug precursor chemicals.
Notes: The legal provisions can be checked word for word, but no one has done a quantitative study of how many fewer problems there are when you take a drug by prescription than when you buy it yourself, so it is rated B as “hard to quantify.” The steroids and sex hormones discussed in §28.5, §28.7 follow the same rules. When it has truly reached the point of using drugs to lose weight, the doctor first looks at body mass index, whether you have other illnesses and whether there are conditions that rule out drug use, and then decides whether to prescribe and which one. That judgment cannot be bought.
Evidence grade: B : Supported by research but without a precise number, or based on small or single studies.
Sources: 国家市场监督管理总局 (2023). 药品经营和使用质量监督管理办法（总局令第 84 号）. https://www.gov.cn/gongbao/2023/issue_10846/202311/content_6917322.html
国家市场监督管理总局 (2022). 药品网络销售监督管理办法（总局令第 58 号，第八条至第十条）. https://www.gov.cn/gongbao/content/2022/content_5717002.htm

Translated from the Chinese original. Original book, section 28, tip 6. This section is about health and medicines. It is general information, not a substitute for a doctor’s diagnosis or prescription. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer