6.1 Factors influencing drug effects

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

1. the drug itself
2. the individual user
3. the environment in which drug use occurs.

In this topic we will be focusing on the factors relating to the drug itself.

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:

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

Unexpected drug effect

Brainstorm/group activity

Question - 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.