Most people take medicines only for the reasons their doctors prescribe them. But an estimated 20 percent of people in the United States have used prescription drugs for nonmedical reasons. This is prescription drug abuse. It is a serious and growing problem. Abusing some prescription drugs can lead to addiction. You can develop an addiction to: Narcotic painkillers Sedatives and tranquilizers Stimulants Experts don't know exactly why this type of drug abuse is increasing. The availability of drugs is probably one reason. Doctors are prescribing more drugs for more health problems than ever before. Online pharmacies make it easy to get prescription drugs without a prescription, even for youngsters.