What does it mean to prescribe or administer medication "off-label"?

Prescribing a medication “off-label” is a common practice in the medical field.  More than one in five outpatient prescriptions written in the U.S. are “off-label”.  What does it mean to prescribe or administer medication “off-label”? Drugs apply for FDA approval for the treatment of a specific condition.  This is a costly and rigorous process which involves proving the safety and efficacy of said medication for a specific condition. When a drug is prescribed “off-label” the drug does have FDA approval, however that approval was for the treatment of a condition other than the one for which your doctor is prescribing it.  For instance, Propranolol is a beta-blocker which has FDA approval for the treatment of hypertension and the prophylaxis of angina pectoris.  It has also been shown to be very effective in treating performance anxiety and is commonly prescribed for this even though it does not have FDA approval for treatment of anxiety.  This is an “off-label” administration. Ketamine is another such drug. It is an FDA approved anesthetic and pain medication which has been shown "off-label" to be 70-80% effective in treating mood disorders.