B1.3 The Use and Abuse of Drugs

B1.3 The Use and Abuse of Drugs



Drugs affect our body chemistry. Medical drugs are developed and tested before being used to relieve illness or disease. Drugs may also be used recreationally as people like the effect on the body. Some drugs are addictive. Some athletes take drugs to improve performance. People cannot make sensible decisions about drugs unless they know their full effects.


Types of drugs

  • Medical drugs:
    • Prescribed – a doctor must provide a prescription for these to be obtained.
      • Eg antibiotics and strong pain killers such as morphine.
    • Non-prescribed – these can be bought in a chemist without a prescription.
      • Eg pain killers such as aspirin and paracetomol, and cough medicine.
    • Recreational drugs:
      • Legal – eg alcohol, caffeine, nicotine
      • Illegal – eg ecstasy, cannabis and heroin


Drug trials

  • Scientists are continually developing new drugs.
  • When new medical drugs are devised, they have to be extensively tested and trialled before being used.
  • Drugs are tested in a series of stages to find out if they are safe and effective.
  • New drugs are extensively tested for toxicity, efficacy and dose:
    • in the laboratory, using cells, tissues and live animals
    • in clinical trials involving healthy volunteers and patients.
      • Very low doses of the drug are given at the start of the clinical trial.
      • If the drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug.
      • In some double blind trials, some patients are given a placebo, which does not contain the drug.
      • Neither the doctors nor the patients know who has received a placebo and who has received the drug until the trial is complete.



  • Thalidomide is a drug that was developed as a sleeping pill.
  • It was also found to be effective in relieving morning sickness in pregnant women.
  • Thalidomide had not been tested for this use.
  • Unfortunately, many babies born to mothers who took the drug were born with severe limb abnormalities.
  • The drug was then banned.
  • As a result, drug testing has become much more rigorous.
  • More recently, thalidomide has been used successfully in the treatment of leprosy and other diseases.



  • Statins are a relatively new group of drugs used to lower blood cholesterol levels.
  • A high cholesterol level increases a person’s risk of having a heart attack or stroke.
  • The long-term use of statins reduces the risk of such an event and can increase the life expectancy of people with a history of heart disease.
  • People are concerned that these drugs could encourage people to lead an unhealthy lifestyle in the belief that they can reduce their cholesterol levels.


Drug Abuse

  • Some people use drugs recreationally.
  • Some of these recreational drugs are more harmful than others.
  • Some of these drugs are legal, such as alcohol and nicotine.
  • Some of these drugs are illegal such as ecstasy, cannabis and heroine.
  • Some of these drugs are prescribed but are not taken sensibly, such as sleeping tablets, antidepressants and strong pain killers such as morphine.
  • The overall impact of legal drugs on health is much greater than the impact of illegal drugs, because far more people use them.


Addiction and Withdrawal

  • Drugs change the chemical processes in people’s bodies.
  • Drugs work by affecting synapses.
  • Some drugs make them work faster (eg, caffeine).
  • Some drugs make them work slower (eg. cannabis).
  • Drug abusers may become dependent or addicted to the drugs.
  • They may suffer withdrawal symptoms without them.
  • Heroin and cocaine are very addictive.
  • There are concerns about the possible progression from people taking non-addictive recreational drugs to addiction to hard drugs.
  • For example, cannabis is referred to as a gateway drug; it is thought that it leads to people taking cocaine or heroin.


Effects of drugs

  • Alcohol affects the nervous system by slowing down reactions.
    • It helps people relax.
    • Too much may lead to lack of self-control, unconsciousness or even coma.
    • Long term abuse eventually damages the liver and brain.
  • Nicotine is the addictive substance in tobacco smoke.
    • This makes it difficult for people to stop smoking.
    • Nicotine patches and nicotine chewing gum can be used to help people stop smoking.
  • Tobacco smoke contains carcinogens, which are chemicals that cause cancer:
    • The link between smoking tobacco and lung cancer has been known about for about 100 years.
    • However, this was only gradually accepted.
  • Tobacco smoke also contains carbon monoxide which reduces the oxygen-carrying capacity of the blood.
    • In pregnant women this can deprive a fetus of oxygen and lead to a low birth mass.
  • Ecstasy, cannabis and heroin may have adverse effects on the heart and circulatory system.
  • Cannabis smoke contains chemicals which may cause mental illness in some people.


Drugs in sport

  • There are several types of drug that an athlete can use to enhance performance.
  • Some of these drugs are banned by law and some are legally available on prescription.
  • All are prohibited by sporting regulations.
  • Examples include:
    • Stimulants that boost bodily functions such as heart rate;
    • Anabolic steroids which stimulate muscle growth.
  • Athletes in major sporting events have to be willing to give a blood or urine sample so that they can be tested for these drugs.

Some scientists work to develop drugs that cannot be detected by these tests.