off-label

[awf-ley-buh l, of‐]
adjective Informal.
  1. of, relating to, or denoting a drug prescribed for a particular indication even though the drug has not yet received approval from the Food and Drug Administration for that disease, condition, or symptom.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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Contemporary Examples of off-label