Substance use becomes a problem when it:
gets in the way of work, school or other activities
causes problems with family or friends and other relationships
harms a person’s mental or physical health
creates financial problems.
It is helpful to look at substance use along a continuum ranging from experimental to excessive use. Excessive use may lead to a substance use disorder, another term for addiction.
Experimentation: Many people begin by experimenting because they are curious about how it feels to try different substances.
Occasional use: In time, experimentation may change to occasional use. At this stage, they may use substances socially on weekends or at parties.
Regular daily use: People might then begin to use substances regularly a few days a week—it may be part of their lifestyle, but it is not necessarily a problem. Nonetheless, a pattern may be starting to form that leads to daily or more
frequent use. Some substances can be very addictive, and the pattern of use can become excessive. People may develop tolerance, which means they need to use more of the substance in order to feel the desired effect.
Misuse: Problems are more likely to occur when people increase their use and continue to use excessively, even though there are negative consequences.
Substance use disorder: Addiction occurs when the repeated use of alcohol or other drugs causes problems in day-to-day functioning, such as health problems or failure to meet major responsibilities at work, school or home.