Occasional self-medication has always been part of normal living. The making and selling of drugs have a long history and are closely linked, like medical practice itself, with the belief in magic. Only during the last hundred years or so has the development of scientific techniques made it possible for some of the causes of symptoms to be understood, so that more accurate diagnosis has become possible. The doctor is now able to follow up the correct diagnosis of many illnesses with specific treatment of their causes. In many other illnesses, of which the causes remain unknown, it is still limited, like the unqualified prescriber, to the treatment of symptoms. The doctor is trained to decide when to treat symptoms only and when to attack the cause: this is the essential difference between medical prescribing and self-medication