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Medicines to treat disease

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Drugs in the body - legal drugs (teacher explanation for this page is recommended)

Medicines are taken to treat disease and, although they may have side effects, they generally make ill people better. Drugs, on the other hand have no beneficial effects on the body.

Cigarettes and alcohol are legal drugs.


The animation starts with normal breathing. When you smoke you breathe tobacco smoke down into your lungs – the animation shows this happening. Tobacco smoke contains harmful chemicals. One of these, tar, coats the air sacks in the lungs. This damages them and can lead to diseases such as cancer. 

Other chemicals are absorbed into the blood, one of these is nicotine. Nicotine affects your brain and makes you feel relaxed, but it is also addictive. Addictive drugs change the chemical processes in your body so that you may become addicted to them (dependent on them). If you are addicted to a drug you cannot manage properly without it. Once you are addicted to a drug, you generally need more and more of it to keep you feeling normal. When addicts try to stop using drugs they usually feel very unwell. They often have aches and pains, sweating, shaking, headaches and cravings for their drug. These are known as withdrawal symptoms. This makes it hard for many people to stop smoking. 

Nicotine and other chemicals also affect other parts of your body and can cause heart disease and other diseases of the circulatory system.

Drinking Alcohol

Alcohol is a drug which you drink. The animation shows a drink going down into the stomach and then into the rest of the gut. Alcohol is absorbed into your blood through the walls of the stomach and the small intestine.

Alcohol travels all around the body in your blood stream – shown on the animation. From your blood the alcohol passes easily into nearly every tissue of your body including your nervous system and brain. It slows down your reactions. It can make you lose your self-control. When you have had too much to drink you lack judgement and often make stupid or dangerous decisions (you are drunk).

Alcohol is poisonous, but your liver can usually break it down and get rid of it before it causes serious harm. If you drink large amounts of alcohol your liver simply cannot cope and you suffer from alcohol poisoning. This can quickly lead to unconsciousness, coma and death.