What are illegal drugs?

What are illegal drugs?

A drug is a substance that affects the way the body functions. If a drug is classified as ‘illegal’, this means that it is forbidden by law. Different illegal drugs have different effects on people and these effects are influenced by many factors. This makes them unpredictable and dangerous, especially for young people.

The effects of a drug are influenced by:

• The type of drug
• How much is consumed
• Where the person is when the drug is being used
• What the person is doing while using the drugs
• Individual characteristics such as body size and health vulnerabilities
• How many different drugs are taken at one time (See Polydrug use: Factsheet)

Types of illegal drugs

Below are some types of illegal drugs. Click the link to find out more about each drug, its effects and potential harms. 

• Cannabis (Marijuana)
• Cocaine
• MDMA/Ecstasy
• GHB
• Hallucinogens
• Heroin
• Inhalants
• Ketamine
• Methamphetamine

Drugs and their classification

Depressants are drugs that slow down the central nervous system and the messages that go between the brain and the body. These drugs decrease people’s concentration and slow down their ability to respond. The name ‘depressant’ suggests that these drugs can make a person feel depressed, but this is not always the case. The term depressant purely refers to the effect of slowing down the central nervous system. Some examples of depressants include: alcohol, opioids (e.g., heroin), barbiturates, GHB.

Stimulants (also referred to as psychostimulants) are drugs that stimulate the central nervous system and speed up the messages going between the brain and the body. These drugs typically increase energy, heart rate and appetite. Some examples of psychostimulants include: methamphetamine (speed, ice, base), cocaine, dexamphetamine, caffeine, nicotine, MDMA/ecstasy.

Hallucinogens are drugs which typically alter how a person perceives the world. These drugs can change the way a person sees, hears, tastes, smells or feels different things, including experiencing things that aren't there at all. Some examples of hallucinogens include: ketamine, magic mushrooms, LSD.

To find out more, read our Hallucinogens factsheet. 

Illegal Drug FAQs

Read our factsheets to find the answers to some frequently asked questions about illegal drugs:

• What happens if I am caught with an illegal drug? Read Drug and alcohol use and the Law: Factsheet
• What if I can't say no? Read Making Choices: Factsheet
• How to help a friend or family member with their drug or alcohol use
• How do I help someone who has taken an illegal drug?

Evidence Base

This factsheet was developed following expert review by researchers at the Matilda Centre for Research in Mental Health and Substance Use at the University of Sydney, the National Drug & Alcohol Research Centre at the University of New South Wales, and the National Drug Research Institute at Curtin University.

See Teacher Booklet, Parent Booklet or Student Booklet for more information.