The term off label prescribing refers to use of a drug in a manner not approved by the regulatory authorities. The term also applies to the use of a marketed medication in a patient population, dosage, or dosage form that does not have regulatory approval. The practice of off label prescribing is widespread and is seen in almost all branches of medicine. The usage may be supported by strong scientific evidence and research but it does not guarantee the safety of the drug in a large population. Therefore this review focusses on usage of off label medications in different fields of medicine, the possible reason for the use and possible benefits and harms of off label prescribing