Final answer:
The prescription of a drug for treatment other than what's labeled by the FDA is known as off-label use. It is a common and legal practice in medicine.
Step-by-step explanation:
The Food and Drug Administration (FDA) approves prescription drugs for the treatment of specific conditions as stated on the drugs' labeling. However, a physician may prescribe a drug for an indication that is not included in the approved labeling. This practice is known as off-label use. It is not illegal and is a common practice in medicine to use drugs in ways that are found to be safe and effective, but that have not yet been approved by the FDA for that specific use.