text: definition of drug and medicine and what is the diference between them?   a drug is anything besides food that alters the way your body runs.  a medicine is a type of drug designed to help you in a certain way (fighting off disease for example).  but there are other types of drugs too, illicit drugs that will make your body respond a certain way which is not necesarily to help you.  a medicine is a drug, but a drug is not necesarily a medicine.