A drug is a substance that alters the way your body works. The two main groups of drugs are:

  • Medicinal drugs – Used to treat, prevent or diagnose a wide range of conditions and diseases, and are typically prescribed by a healthcare professional.
  • Recreational drugs – Used for pleasure or enjoyment, and are not typically prescribed for any medical purpose.

Medicinal drugs

Pharmaceutical companies develop and produce medicinal drugs to treat various medical conditions and diseases. These drugs are prescribed by doctors to help reduce symptoms and improve the overall health and well-being of patients.

When drugs are prescribed, they must be taken correctly or they can result in harmful side effects or overdose.

There are many different types of medicinal drugs, each designed to treat specific conditions or diseases. Some common examples are:

  • Painkillers
  • Antibiotics
  • Vaccines


Painkillers are medications that generally relieve pain without addressing the underlying cause. Some examples of painkillers are paracetamol and aspirin, which can be used to treat headaches and sore throats.

Although painkillers can provide relief, it is important to address the underlying cause of the pain through proper treatment. It’s also important to follow the instructions when taking painkillers to avoid potential harm.

Recreational drugs

Recreational drugs are substances that people take for the pleasurable effects on their mind and body. These substances are not usually taken for medical purposes.

Recreational drugs can be legal or illegal, and they can be classified as either depressants or stimulants.

Legal drugs

In the UK, some examples of legal recreational drugs are:

  • Coffee
  • Caffeine
  • Tobacco

Legal recreational drugs, such as alcohol and caffeine, are widely available and socially acceptable. However, they can still lead to long-term health problems and may even cause death.

Alcohol, for example, can cause liver damage, high blood pressure, and addiction when consumed in excess. Caffeine can lead to insomnia, anxiety, and digestive issues when consumed in large amounts. Tobacco is also a legal recreational drug, but it is well-known to cause serious health problems such as lung cancer, heart disease, and stroke.

Illegal drugs

Illegal recreational drugs are substances that are banned by law due to their high potential for abuse and negative impacts on health. In the UK, some examples of illegal recreational drugs are cocaine, heroin and ecstasy.

These drugs are highly dangerous and addictive. They can also have severe consequences for both short-term and long-term health.

Classification of illegal drugs

In many countries, illegal drugs are classified into different categories or schedules based on their potential for abuse and the risks they pose to public health.

In the United Kingdom, for example, illegal drugs are classified into three main categories:

  • Class A – Considered the most dangerous and includes substances such as cocaine, heroin, and methamphetamine.
  • Class B – Less harmful but still posing a significant risk of abuse; includes substances such as amphetamines.
  • Class C – Considered the least harmful; includes substances such as anabolic steroids and some tranquillisers.


Repeated use of both medicinal and recreational drugs can lead to addiction. The person suffering from addiction will be dependent on the drug to the point where they will need it to feel normal.

When a person with an addiction does not have access to the drug, they may experience a range of negative symptoms, commonly known as withdrawal symptoms. These can include both physical and mental effects, and the severity of the withdrawal depends on the specific drug and the person’s level of dependence.