Module 6: how drugs work: learner's workbook

11.2 Thorley's model of drug-related harm

Page last updated: 2004

Thorley's model of problematic drug use also assists our understanding of drug-related harm. Thorley's model focuses on the problems related to different patterns of drug use. This model identifies the possible problems associated with dependence, regular use and intoxication and the overlap between these factors. (See Diagram)

While there may be some overlap between the type of use and associated harms, there are also many separate issues related to the different types of use.

It is important to remember that the majority of young people will not experience problems related to dependent use. Most of their difficulties will arise from intoxication (using at hazardous levels) or regular use (e.g. a couple of drinks of alcohol each night with friends).

However, a smaller proportion of long-term excessive users will experience some dependence-related problems as they develop a tolerance to the drug and a need to use for both psychological and physical reasons.

Diagram: Thorley's model of harm relating to intoxication, regular use and dependency

Text equivalent below for Diagram: Thorley's model of harm relating to intoxication, regular use and dependency
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Text version of Diagram

Thorley's model is illustrated by three circles that overlap each other. Each circle represents dependence, regular use, and intoxication.


Problems associated with dependence:
  • discomfort when refraining from use
  • inability to rest
  • phobias
  • isolation
  • withdrawal
  • anxiety
  • social problems
  • homelessness
  • loss of control

Regular use

Continued use over a longer period of time can result in the following:
  • medical and health problems
  • child neglect
  • withdrawal
  • family problems
  • relationship problems
  • financial problems


The following problems can arise from a single occasion of use:
  • accidents
  • aggression/violence
  • marital disputes
  • suicides
  • drink driving
  • drowning
  • legal problems