Addiction: Definitions and key concepts
Key concepts in substance use
When a person needs higher doses of a substance to produce the same effects they experienced during earlier use, they have developed tolerance. People often develop tolerance while they are physically dependent on a substance (Portico, 2017).
When a person reduces or stops their substance use after a period of using regularly, they experience withdrawal symptoms. This results in unpleasant sensations and feelings.
A person’s withdrawal symptoms are opposite to the main effect of the substance used. For example:
Physical dependence is a bodily state that may develop with regular drug use. It includes withdrawal symptoms and increased tolerance (Portico, 2017).
When at least three of the following occur in the same 12-month period, it is considered physical dependence (WHO, n.d.):