Has the potency of cannabis changed over time?

Illicit cannabis appears to be more potent now than it was in previous years. The potency of cannabis is determined by several factors including:

  • the level of delta-9-tetrahydrocannabinol (THC - the main psychoactive chemical in cannabis)
  • the way the cannabis plant is grown (e.g., hydroponics)
  • the part of the cannabis plant used (e.g., head vs. leaf)
  • the way cannabis is prepared for use (e.g., pipes/bongs vs. joints).

Source: Adapted from the DrugInfo (2018) and Alcohol and Drug Foundation (2018) websites.