Last updated : September 24, 2017

What is a drug?

A drug is any substance that, when taken or administered into the body has a physiological effect.

A psychoactive or psychotropic drug affects mental processes and can influence mood, behavior, cognition and perception.

What are the laws about drugs?

Legal drugs

Some drugs, such as alcohol, caffeine, nicotine and various prescribed and over-the-counter medications, are legal but may be subject to restrictions based on age, location of use, driving and point of sale regulations.

The active ingredients in legal drugs can be regulated and controlled; the alcohol content of drinks or the milligrams of nicotine in cigarettes.

Illegal drugs

Other drugs such as cannabis, amphetamines, ecstasy, cocaine and heroin, are illegal. They are not subject to quality or price controls and the amount of active ingredient is not consistent. A person using illegal drugs can never be sure of how strong the drug is, or what is actually in it.

Different batches of an illegally manufactured drug may have different amounts of the drug and other unidentified additives.

Federal and state laws provide penalties for possessing, using, producing, selling or driving under the influence of illicit drugs. Penalties can include fines, imprisonment, rehabilitation orders and disqualification from driving.

Some states and territories have programs that refer people with a drug problem to treatment and/or education programs where they can receive help rather than going through the criminal justice system.

Why do people use drugs?

People use drugs for many reasons; to relax, for enjoyment, to be part of a group, out of curiosity, as a coping mechanism or to minimize physical and/or psychological pain and trauma.

They use drugs for the benefits (perceived and/or experienced), not for the potential harm. This applies to both legal and illegal drugs.

Types of drug use 

These are some of the different categories of drug use. People may use drugs in one or several categories, and one stage will not inevitably lead to another.

Experimental use: a person tries a drug once or twice out of curiosity.

Recreational use: a person chooses to use a drug for enjoyment, particularly to enhance a mood or social occasion.

Situational use: a drug is used to cope with the demands of particular situations.

Intensive use or ‘bingeing’: a person consumes a heavy amount of drugs over a short period of time, and/or uses continuously over a number of days or weeks.

Dependent use: a person becomes dependent on a drug after prolonged or heavy use over time. They feel a need to take the drug consistently in order to feel normal or to avoid uncomfortable withdrawal symptoms.

How could drugs affect you?

The effects of any drug vary from person to person. How a drug affects a person can depend on their size, weight and health, also whether the person is used to taking the drug, and whether other drugs are in their system at the same time.

The effects will also depend on the amount taken. It can be hard to judge how much of an illegal drug has been taken, as they are uncontrolled, so quality and strength will vary from one batch to another.


These include alcohol, benzodiazepines (minor tranquillisers), cannabis, GHB, heroin, morphine, codeine, methadone, and some inhalants.

Depressants do not necessarily make a person feel depressed. They affect the central nervous system, slowing down the messages between the brain and the body.

They can affect concentration and coordination. They slow down the person’s ability to respond to unexpected situations. In small doses they can cause a person to feel more relaxed and less inhibited. In larger doses they can cause drowsiness, vomiting, unconsciousness and death.


These include caffeine, ephedrine, nicotine, amphetamines, cocaine and ecstasy (MDMA).

Stimulant drugs speed up the messages between the brain and the body. The can make a person feel more awake, alert, confident or energetic.

Large doses of stimulants can cause over-stimulation, causing anxiety, panic, seizures, headaches, stomach cramps, aggression and paranoia. Long-term use of strong stimulants can also cause these effects.


These include ketamine, LSD, datura, magic mushrooms (psilobycin) and mescaline (peyote cactus). Cannabis and ecstasy can also have hallucinogenic qualities.

Hallucinogens distort a person’s perception of reality. People who have taken them may imagine they see or hear things, or what they see may be distorted. The effects of different hallucinogens vary.

There is no safe level of drug use. Use of any drug always carries some risk—even medications can produce unwanted side effects. It is important to be careful when taking any type of drug.

Other effects of drug use

Pregnancy and breastfeeding

Many drugs can cross the placenta and affect the unborn child.

Read more about the effects of drugs on pregnancy and breastfeeding.

Drugs and driving

It is dangerous to drive after taking drugs. The effects of drugs can affect driving ability, increasing the chance of an accident.
Symptoms of withdrawal and ‘coming down’ after drug use can also affect driving ability.

Read more about the effects of drugs on safe driving.

Drugs and the workplace

Under occupational health and safety legislation, all employees have a responsibility to make sure they look after their own and their co-workers’ safety.

The effects of drugs, and the symptoms of coming down and withdrawal, can affect a person’s ability to work safely and effectively.

Find out about the Alcohol and Drug Foundation’s Good Hosts program, assisting organisations to manage alcohol-related risk in the workplace.

Read about the risks and responsibilities involved with alcohol in the workplace.

Tolerance and dependence

There is evidence that after prolonged use, many drugs can cause dependence. People who use a drug regularly can develop dependence and tolerance to it. This means they need to take larger amounts of the drug to get the same effect.

Dependence on a drug can be psychological, physical, or both. People who are dependent on the drug find that using the drug becomes far more important than other activities in their life. They crave the drug and find it very difficult to stop using it.

People who are psychologically dependent on a drug may find they feel the urge to use it when they are in specific surroundings, such as socialising with friends.

Physical dependence occurs when a person’s body adapts to a drug and gets used to functioning with the drug present.

Getting help

In Australia, there are many different treatment options for drug problems. Some aim to help a person stop using a drug, while others aim to reduce the risks and harm related to their drug use.

Read more about treatment.


If a dependent person stops taking a drug, they may have withdrawal symptoms and cravings while their body gets used to functioning without the drug.

Note: Seek medical advice for withdrawal from alcohol or benzodiazepines, as it may cause seizures.

Read more about withdrawal.

What to do if you are concerned about someone’s drug use

If you are concerned about someone’s drug use, there is help available. Contact the alcohol and drug information service in your state or territory.

What to do in a crisis

Always call triple zero (000) if a drug overdose is known or suspected and remember that paramedics are not obliged to involve the police. If someone overdoses or has an adverse reaction while using GHB, it is very important that they receive professional help as soon as possible. A quick response can save their life.

Read more about overdose.

Preventing and reducing harms

Many Australians take at least one psychoactive drug on a regular basis—they might take medication (i.e. over-the-counter or via a prescription), drink alcohol, smoke tobacco or use an illegal drug. All drugs have the potential to cause harm. As use increases, so does the potential for harm.

Australia’s national drug policy is based on harm minimisation. Strategies to minimise harm include encouraging people to avoid using a drug, through to helping people to reduce the risk of harm if they do use a drug. It aims to reduce all types of drug-related harm to both the individual and the community.