All models are approximations… but some models are useful. So the question you need to ask is not “Is the model true?” (it never is) but “Is the model good enough for this particular application?”
Box, G. E. P., Luceno, A., & del Carmen Paniagua-Quinones, M. (2011, p.61). Statistical control by monitoring and adjustment. John Wiley & Sons.
Despite the Drugs Wheel's reach, it is not a 'perfect' or 'correct' model of classifying drugs. It can be criticised on a number of fronts, and with this in mind, three people involved in the Drugs Wheel have also come up with another way of looking at drug effects, that draws heavily on earlier work such as the Drugs World Venn diagram, itself based on Derek Snider's Drug Venn diagram, and the Drugs Pyramid. The Drugs Venn uses the 'traditional' three main categories, and the overlaps between them allow for greater flexibility, and discussion about crossovers between categories and drug effects. For more information on methods of classification, the Drugs Wheel, and Drugs Venn we have written a peer-reviewed paper that is Open Access (free) entitled Jump-starting the conversation about harm reduction: making sense of drug effects, published by Drugs: Education, Prevention and Policy.
The Drugs Venn was designed by Fiona Measham (founding Director of The Loop), Guy Jones (senior chemist with The Loop, senior advisor on the Drugs Wheel, and technical lead at Reagent Tests UK). A video of Guy and Mark chatting about drug taxonomies can be found here. Additional changes were then made in close consultation with Fiona Spargo-Mabbs from @foundationdsm and Nick Hickmott from @WithYouInKent.
The Drugs Venn has the same licensing terms as the Drugs Wheel (Creative Commons Attribution-Non Commercial-ShareAlike 4.0 International License). Click here for contact details.
Changelog
Thanks to all for the feedback on this Twitter thread, and other discussions.
All versions: added keys/tables to all versions and 'effects by category' to headers to clarify that the model, and overlapping areas are about drug effects, as opposed to risks; added additional credits.
Main version 1.1: removed [plant sources]; all drugs now fit into either a category or overlap area, as drugs 'spilling over' was confusing; cannabinoids merged into the centre area; CBD separated from other cannabinoids and moved to depressants; 4-FA moved to Stim-Psy overlap; adjusted positions of opioids, opiates, and ketamine-like drugs.
1.2: Removed CBD following discussion.
YP version 1.0: separate Venn created following requests by YP workers, with intentionally limited numbers of drugs; each features a link to harm reduction pages.