Our findings suggest greater THC concentrations in cannabis resin, which is produced by extracting material from the cannabis plant. The increase in potency of cannabis resin in Europe may be attributable to a shift towards THC-dominant cannabis plants in Morocco - the primary producer of cannabis resin for the European market [77]. The increased THC concentrations in resin may translate into greater risk of harm for users preferring this type of cannabis. Possibly, the increased risk could be offset by dose titration [78] or higher concentration of cannabidiol found in resin (for data on concentration, see [72]; for the effects of cannabidiol, see [79]). However, as findings on the protective effects of cannabidiol have been inconsistent [80], it remains to be studied empirically whether resin use is associated with an increased risk.
