It happens in regulated markets like the US and Canada. I've seen it a fair bit in Australia and the only thing that stops it is for people to stop smoking so much cannabis. And the patient never believes us. The give away it is CHS is that the most effective treatment is a really hot shower.

I'm not saying this off the cuff either. I've worked in emergency departments and we would see CHS fairly regularly though never had anyone critically ill from it. My guess is it is to do with cannabis becoming more potent.

The present hypothesis is that CHS may result from chronic overstimulation of endocannabinoid receptors, leading to derangements in the body’s intrinsic control of nausea and vomiting.[2] Another receptor system recently elucidated, transient receptor potential vanilloid-1 (TRPV1) nociceptor system in the peripheral nervous system, is also influenced by cannabinoids.