Off-label use of a prescription drug is when this drug is used for other indications that for those which it was approved, or that is given to a group for which it was not approved, or the dosage prescribed is different from the one mentioned. Off-label use of drugs is very common. In many countries, drugs need to show that they are effective against a given condition in clinical trials. Before these trials are done, drugs cannot legally be used for indications other than those for which they were tested. 