The British National Formulary (BNF) is a medical and pharmaceutical reference book that contains a wide spectrum of information and advice on prescribing and pharmacology, along with specific facts and details about all medicines, including indication(s), contraindications, side effects, doses, legal classification,  and generic formulations.

Though it is a national formulary, it nevertheless also includes entries for some medicines which are not available under the NHS and must be prescribed and/or bought privately. A symbol clearly denotes such drugs in their entry.

It is used by doctors (both general practitioners and specialist practitioners), and by other prescribing and non-prescribing healthcare professionals (such as nurses, paramedics, and pharmacists) to help them use drugs optimally to care for patients as appropriately as possible.