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. The advance of technology has brought about much progress in some fields of medicine, including the development of scientific drug therapy. In many countries public health organization is improving and people's nutritional standards have risen. Parallel with such beneficial trends have two adverse effects. One is the use of high-pressure advertising by the pharmaceutical industry, which has tended to influence both patients and doctors and has led to the overuse of drugs generally. The other is the emergence of the sedentary society with its faulty ways of life: lack of exercise, over-eating, unsuitable eating, insufficient sleep, excessive smoking and drinking. People with disorders arising from faulty habits such as these, as well as from unhappy human relationships, often resort to self-medication and so add the taking of pharmaceuticals to the list. Advertisers go to great lengths to catch this market. Clever advertising, aimed at chronic sufferers who will try anything because doctors have not been able to cure them, can induce such faith in a preparation, particularly if steeply priced, that it will produce—by suggestion—a very real effect in some people. Advertisements are also aimed at people suffering from mild complaints such as simple colds and coughs, which clear up by themselves within a short time. These are the main reasons why laxatives, indigestion remedies, painkillers, tonics, vitamin and iron tablets and many other preparations are found in quantity in many households. It is doubtful whether taking these things ever improves a person's health; it may even make it worse. Worse because the preparation may contain unsuitable ingredients; worse because the taker may become dependent on them; worse because they might be taken in excess; worse because they may cause poisoning, and worse of all because symptoms of some serious underlying cause may be masked and therefore medical help may not be sought.