Surveillance of Cannabis Strains Using Online Data: Observational Study

The flower strains of cannabis are an important attribute that determines product appeal and health impacts. However, there is a lack of surveillance of cannabis strains as the marketplace expands in response to the growing legalization of recreational and medical cannabis.

This study aimed to analyze cannabis strains and their growth using existing data from user-generated reviews on the Leafly website.

Using the time stamps of each review, we constructed a dataset of the number of reviews by strain and year over the period of 2010 to 2023. We further conducted trend analyses using Joinpoint regression.

As of December 2023, more than 7000 cannabis strains are available for view or purchase on the website, including more than 6000 that have been reviewed by users or customers. The number of strains with reviews experienced a 13-fold increase from 280 strains in 2010 to 3905 strains in 2023. Strains that are hybrid and contain more than 20% tetrahydrocannabinol experienced the highest growth in review numbers.

The rapid growth of strain numbers poses challenges to cannabis regulation. Policymakers who would like to base regulations on product features need to consider the variability of strains, along with other features such as potency levels and product forms.