A drug is a substance which is taken into the body. Some drugs are taken for illnesses and some are taken for fun. Usually a doctor will give you a drug for an illness to make you well. People take drugs for fun because they affect their body or thoughts in unusual ways. Fun drugs are called "recreational" and drugs for illnesses are called "therapeutic".
Drugs can be taken by eating, smoking or injecting them. Drugs often have bad effects as well as the good effect - these bad effects are called side-effects.
Drugs need to be taken in theright amount. The amount of the drug you take is called a dose. If you take too much of a drug, you can get very sick or even die. If a doctor tells you how much of a drug (the right dose) to take, you should only take that amount. It is also very important to keep taking the drug until the doctor says to stop, because even if you feel better you may still be sick. When a doctor tells you what drug you need to take, how much, and for how long, it is called a prescription.
Drug-Substances other than food that change the structure or function of the body or mind.