Prescribing according to diagnosis: how psychiatry is different

Most countries in the modern world have a formal system of medicines regulation. Medicinal drugs, or more specifically their formulation and dosage, are licensed or “labelled” for certain specific indications in which their use has been shown to be broadly safe and beneficial. Prescribers can, as a consequence, have confidence in the assumption that a drug licensed for a particular precisely defined ailment is likely to be effective in that condition. Outside this regulatory framework is a body of literature which may relate to other, unlicensed or “off‐label” uses. Sometimes the extra‐regulatory evidence base amounts to no more than a handful of case reports, but often there are published and successful randomized controlled trials. The licensed uses of a medicine are thus merely those for which formal approval has been sought and obtained by the manufacturer. Other beneficial uses are certainly not precluded by a drug's label.