Module 6: how drugs work: facilitator's guide

6.1 Factors influencing drug effects

Page last updated: 2004

The effect of any drug on an individual is the result of three interacting factors:

  • the drug itself
  • the individual user
  • the environment in which drug use occurs.
The effect that a drug has on a person is determined by many factors. The primary factors that influence drug effect are the type of drug and the quantity used.

Other factors include:

Overhead transparency

  • time taken to consume the drug (10 minutes vs 10 hours)
  • tolerance (e.g. regular cannabis smoker vs na´ve smoker)
  • gender, size and amount of muscle
  • other psycho-active drugs in the person's bloodstream (poly-drug use)
  • mood or attitude of the user (e.g. angry vs calm, confident vs fearful)
  • expectation of the drug effect (e.g. expecting a powerful drug effect vs expecting a modest drug effect)
  • setting or environment in which the drug was consumed (e.g. wild party vs quiet night at home).

Unexpected drug effect

Group activity

Recall a time when a drug (psycho-active or not) had an unexpected effect on you or someone you know. Briefly outline the situation, and identify which of the above factors may have contributed to the drug effect. Discuss with group.