indication

An indication is the reason to use a drug: the disease, condition, or situation for which the drug is the right tool. If a drug is a tool in a toolbox, the indication is the job it is meant for. A hammer's 'indication' is a nail; a drug's indication might be high blood pressure, infection, or pain.

In regulated medicine, the approved indication is the specific use that a regulatory agency has reviewed and authorized after seeing evidence that the drug is safe and effective for that purpose. The approval is usually quite precise, naming the condition and often the patient population, severity, or line of treatment. This approved indication appears on the official label and shapes how the drug is marketed.

Indication is the opposite of contraindication, a situation in which the drug should not be used. The two together frame appropriate prescribing. Note that a drug can be legitimately used outside its approved indications, called off-label use, when good clinical judgment and evidence support it; the indication on the label is a regulatory statement, not the full boundary of medical practice.