There is mounting evidence to support the existence of a syndrome afflicting heavy cannabis users, after the world's first cases were found in South Australia.

The condition "cannabinoid hyperemesis" was first identified in a group of about 20 heavy drug users in the Adelaide hills in 2004, and a new case has emerged this time in the US.

The syndrome is characterised by nausea, stomach pain and bouts of vomiting - ill effects which, oddly, sufferers say they get some relief from by having a hot shower or bath.

The new case, involving a 22-year-old man in Omaha, is published in the where doctors were also told to consider it when treating people with unexplained vomiting.

"Given the high prevalence of chronic cannabis abuse worldwide and the paucity of reports in the literature, clinicians need to be more attentive to the clinical features of this under-recognised condition," writes Dr Siva Sontineni, and colleagues, from the Creighton University Medical Centre.