What is a drug? Broadly, one could define a drug as any chemical substance that is not one of the basic nutrients (proteins, fats, carbohydrates, and vitamins and minerals) and that, when taken into the body, alters the body’s structure or function.
By that definition, though, ordinary table salt could be labeled a drug. And so could a host of other substances – pesticides, or the venom injected by a rattlesnake, for example – which might find their way into the body accidentally, with devastating impact.
But most people would not think of either table salt or pesticides as drugs, so we can narrow our definition a bit and establish a specific one for our purposes. The term drug, as used in the text, will mean nonfood substances that are deliberately introduced into the body in order to produce some physiological or psychological effect.
Drug Effects: "Targeting" Body Problem
"Take two aspirins and call me in the morning," says the physician in the old joke. But in real life a physician cannot be so casual. He or she must prescribe the right medicine for your particular problem, choosing from a huge assortment of drugs, each with its own specific effects in the body.
A fast range of medical conditions can be aided with specific drugs. Prescription drugs are available to:
relieve symptoms (examples: nasal decongestants; headache, relievers; lotions applied to itchy insect bites)
prevent illness (example, vaccines used against diseases such as polio)
control chronic conditions (examples; drugs used to control high blood pressure; anti-inflammatory drugs used for arthritic problems)
treat certain diseases (example: antibiotics used to treat tuberculosis)