How are medicines classified in Hong Kong, and how are “prescription-only medicines” and “over-the-counter medicines” defined?

Medicines in Hong Kong are classified mainly according to their safety risks and whether they contain ingredients listed in the Poisons List. Broadly, they fall into three categories. The first is “prescription-only medicines”, which may be purchased only on a prescription issued by a Hong Kong-registered doctor and under the supervision of a registered pharmacist at a registered pharmacy. They are usually Part I poisons in Substance A of the Poisons List, used to treat more serious conditions and carrying a high risk of misuse. The second is “medicines that may be sold under the supervision of a pharmacist”. These do not require a prescription but must be purchased at a pharmacy under the supervision of a registered pharmacist. They usually comprise Part I poisons in Substance B of the Poisons List. The third is “non-prescription medicines”, also known as proprietary medicines or over-the-counter (OTC) medicines. These may be purchased freely at pharmacies, medicine shops and even some supermarkets and convenience stores. They can be further divided into “Part II poisons” and “non-poison” medicines. This classification system seeks to balance convenient access to medicines with safety, ensuring that higher-risk medicines are used with professional guidance.