Vague term with a variety of meanings depending on the social, medical and legal contexts. For some any use of illicit drugs equates to 'abuse', for others it relates to the excessive use of such drugs.


General term relating to the concepts of tolerance and dependence. According to the World Health Organisation (WHO) addiction is the repeated use of a psychoactive substance to the extent that the user is periodically intoxicated, shows a compulsion to take the preferred substance, has great difficulty in voluntarily ceasing and exhibits determination to obtain the substance by almost any means.


A drug that relieves pain.

Chasing the Dragon

A way of smoking heroin by placing the powder on foil and heating it from below with a lighter. Fumes are inhaled.


How a person feels when the effects of a drug start to wear off.

Controlled drug

A drug whose use is restricted under the Misuse of Drugs Act.

Dance drugs

Stimulant drugs, such as ecstasy, that are commonly taken in clubs.


A drug that dulls the central nervous system, slowing down heart and breathing rates and making the user feel relaxed and drowsy.


Removal of a behaviour or activity from the scope of the criminal justice system. Usually refers to an administrative decision has been made not to prosecute acts which nonetheless remain against the law.


State where the user continues the use of a substance despite significant health, psychological, relational, familial or social problems. Dependence is a complex phenomenon, which may have genetic components. Psychological dependence refers to the psychological symptoms associated with craving and physical dependence to tolerance and the adaptation of the organism to chronic use.


Neuromediator involved with the mechanisms of pleasure.


The process of coming off a drug and getting it out of the body.

Dual diagnosis

Means that both drug use and mental health issues are present and that there is a relationship between the two that makes it difficult to tackle the two independently.


A drug that affects the brain and causes distortions of perception.


The introduction of a drug into a vein.


Not permitted, unlawful.


Regulatory system allowing the culture, production, marketing, sale and use of a substance.


Substance derived from the opium poppy. The term opiate excludes synthetic opioids such as heroin and methadone.

Polydrug users

People using one or more drugs in varying combinations.


A 'Prescription Only Medicine'. Only available from a pharmacy with a prescription.


Substance which alters mental processes such as thinking or emotions.


Using a drug again after a period of being drug free.


Drugs that calm and soothe, relieving anxiety and nervous tension.


A chemical found in the brain that regulates mood.


Mixture of an upper and a downer, usually cocaine and heroin or speed and heroin.


Used injecting equipment.


Tetrahydrocannibol – the main active component of cannabis. In its natural state, cannabis contains between 0.5% and 5% THC. Sophisticated cultivation methods and plant selection, especially female plants, leads to higher levels of THC concentration.


Drug that calms, soothes, relieves anxiety and may cause drowsiness.

Volatile substances

A group of substances which give off vapours that can be inhaled to achieve intoxication.


The unpleasant symptoms a person experiences when they stop using a drug they are dependent on.

Drugs Glossary