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What is a drug?

Overview of the categorisation of drugs.
© University of Hull

When we talk about drugs and drug use we often only think about ‘hard’ drugs and this raises a range of different opinions and possible stereotypes. However, a drug is any chemical substance that causes a change in a person’s mental or physical state. So this could be the caffeinated drink you have at lunch time or the early morning coffee. Therefore, a clear distinction needs to be made and to do this we can use the terms licit and illicit. For this topic, we will be discussing illicit drugs.

The Drug Wheel Please use the Zoom on your browser to view the image above in more detail.

Pharmacologically drugs impact upon the body in different ways. The outer ring of this image identifies substances into categories while the inner rings note particular psychoactive substances within each category. For example, heroin is an opioid while alcohol is a depressant.

Legally drugs are classified by the Misuse of Drugs Act, 1971. Class A substances are deemed to be the most harmful and these include substances such as heroin and crack cocaine. However, substances such as alcohol and tobacco are not covered within the Misuse of Drugs Act.

© University of Hull
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