2. The definition of "drug"

The word "drug" means anything that, even in small amounts, produces changes in the body, the mind or both. This definition, however, does not clearly separate drugs from what we usually think of as food. The difference between a drug and a poison is also unclear. All drugs become poisons in large amounts, and many poisons are useful drugs in carefully controlled amounts. Is alcohol, for instance, a food, a drug or a poison. It can be any of the three, depending on how we use it.