Understanding drug harm

In 2010, experts compared twenty drugs in a UK study. They considered harm to users and harm to others, including health problems, addiction and social harm. These different harms were combined into a score. To understand the chart, we therefore need to look beyond the height of each bar and ask what kinds of damage a drug can cause.

Alcohol is a good example because its effects can reach far beyond the person drinking. It can affect judgement and reactions. A person who drives after drinking may injure passengers or other road users. Harmful drinking can also contribute to violence, family problems and difficulties at work. Alcohol is widely used, so its effects can reach many people. Several criteria for harm to others in this study take the number of people using a drug into account. This helps explain why alcohol has such a high overall score.

Heroin shows why harm to users also needs careful attention. It can cause addiction and dangerously slow breathing. An overdose can be fatal. Injecting drugs carries an additional risk of infection, especially when equipment is shared. These are serious risks for the person using the drug. However, addiction can also damage relationships. As Jörg’s story shows, relatives may be frightened and worried about someone they love. Other drugs have different physical risks: cocaine is a stimulant, but it can put serious pressure on the body, cause heart problems and increase the risk of a stroke. Feeling active does not mean being safe.

Some damage develops more slowly. Smoking tobacco may not cause an immediate crisis, but it can cause cancer after years of use. Nicotine addiction can make stopping difficult. Other people may also be harmed when they breathe in second-hand smoke. This shows why long-term effects matter when drugs are compared. Cannabis and LSD have different patterns of harm again. Cannabis can affect memory, attention and coordination, which may make learning or everyday activities more difficult. LSD does not typically lead to addiction, helping us understand one reason for its lower rating. However, it can cause intense fear and strongly change a person’s perception of reality. A lower rating does not mean that every experience is safe.

The scores are expert assessments, not percentages. They combine different harms in a particular social context. They do not predict what will happen to one person after taking a drug once. The chart is a starting point for comparing and discussing harm, but it cannot tell us everything about an individual person’s risk.