Fig. 3. Effect of cannabis on heat pain perception threshold (HPPT) and heat pain tolerance threshold (HPTT) in the area of primary hyperalgesia (erythema). Data are presented as mean ± SD of the temperature when further warming was stopped by the subject before (baseline) and 2 h after drug administration (n = 17). Cannabis extract did not significantly alter heat pain thresholds, but there was a tendency toward a lower pain tolerance threshold.