Herbal preparations and pharmaceuticals can contain related compounds yet sit under entirely different rules. The division is drawn by what the product claims rather than by what is in it.
The claim defines the category
A product that states it treats, prevents or cures a named condition is generally classified as a medicine, whatever its ingredients.
The same substance sold without that claim usually falls into a food or supplement category with far lighter requirements.
This is why supplement labelling is written so carefully, using general language about function and avoiding any named condition. The wording on a pack is a legal artefact, drafted to stay on one side of a line that has nothing to do with the contents.
Pre-market approval is the real difference
A medicine must be assessed before it is sold. The manufacturer submits evidence and cannot market the product until a regulator agrees.
Supplements in most markets require no such approval. Responsibility for safety sits with the manufacturer, and regulators act after products are on sale.
The practical consequence is that the burden of proof runs in opposite directions in the two systems.
Plant material is genuinely hard to standardise
The compounds in a plant vary with variety, growing conditions, harvest timing and how the material is dried and stored.
Two batches of the same herb can therefore differ substantially in composition even with identical processing.
Producers address this by standardising to a marker compound, which controls one constituent while leaving the rest of the mixture to vary. Where the marker is not the active constituent, standardisation delivers consistency in the measurement rather than in the product.
Enforcement happens after sale
Regulators in supplement markets act on adverse reports, testing programmes and label reviews once a product is available.
That model finds problems eventually but only after exposure, and it depends on reporting systems that capture a small share of incidents.
Recurring findings include products containing less of the named plant than stated, and products found to contain undeclared pharmaceutical ingredients. The second category is the more serious, because a buyer avoiding a drug may be taking one unknowingly.
Traditional-use registration sits between the two
Several jurisdictions created a middle category for products with a long documented history of use in a tradition.
These schemes require quality and manufacturing standards and permit limited claims, without demanding the trial evidence a new drug would need.
The registration attests that the product is made consistently and has been used in a particular way, which is a narrower statement than the packaging usually implies to a buyer.