A substance can be anything that is swallowed, drunk, injected or absorbed to change a person’s mood, perception or consciousness. Examples of substances include alcohol, stimulants such as cocaine or ecstasy (MDMA), cannabis, tobacco, and sedatives.
Some young people commonly use substances as a once-off, occasionally, or continually to experiment, have fun, join in with their peers, or get through a situation (e.g. to stay awake while studying).
If someone is continually using a substance or their substance use is creating problems within their work, school, personal, or social life, then they may have a substance use disorder.