They chemically kill physical or emotional pain and alter the mind's perception of reality. They make people numb. For drugs to be attractive to a person there must first be some underlying unhappiness, sense of hopelessness, or physical pain. Before we address the questions of cause, here is a little background information. In medical terms, a drug is any substance that when taken into a living organism may modify one or more of its functions.
Some drugs produce unwanted side affects.
Some drugs lead to an unhealthy dependency that has both physiological and behavioral roots. The mind is our most important tool. With our mind, we solve the problems we face in life. Drugs do several things that harm one's ability to think or to be fully aware of the present surroundings. These effects continue long after the effects of the drug appear to have worn off.