Drug is one of the medical profession's most valuable tools. Doctors prescribe drugs to treat or prevent many diseases. Every year, penicillin and other germ-killing drugs save the lives of countless victims of meningitis, pneumonia, and other dangerous infectious diseases. Vaccines prevent such diseases as measles, polio, and smallpox. Analgesics lessen or eliminate pain. The use of these and many other kinds of drugs has helped millions of people live longer, healthier lives than would otherwise have been possible.
Most of our useful drugs were unknown before the 1900's. For example, the sulfa drugs and antibiotics, our best germ-fighting drugs, did not come into use until the late 1930's and early 1940's. Before that time, about 30 percent of all pneumonia victims in the United States died of the disease. The new drugs quickly reduced the death rate from pneumonia in the United States to less than 5 percent.
Polio vaccine was introduced in 1955. At that time, polio virus infected about 30,000 to 50,000 people every year in the United States. By 1960, use of the vaccine had reduced the number of new polio cases in the United States to about 3,000 a year. In 1900, most Americans did not live past the age of 47. Today, Americans live an average of more than 70 years, in part because of the use of modern drugs.
But drugs can also cause sickness and death. Any drug, even a relatively safe one, may cause harm if it is used improperly. Aspirin, for example, is one of the safest and most useful drugs. Yet every year, aspirin kills children who mistake the tablets for candy and eat too many of them. Any drug can kill if it is taken in a large enough dose. In addition, the widespread misuse of alcohol, cocaine, heroin, and other addictive drugs has become a serious problem.
We generally use the word drugs to mean only medicines and certain other chemical substances that people use, such as alcohol or marijuana. But pharmacologists, the scientists who study drugs, consider all chemicals that affect living things to be drugs. For example, they classify insecticides, weedkillers, and a wide variety of other substances as drugs. Even the chemicals in automobile exhaust and other substances that pollute the environment act like drugs because they affect living things.
