Cannabis syndrome evidence mounts

There is mounting evidence to support the existence of a new 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 World Journal of Gastroenterology 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.

In the US case, the sufferer had been smoking marijuana daily and in heavy doses for six years. This eventually led to bouts of vomiting lasting two to three hours daily, and this was worse after meals.

As with South Australian cases, the young man initially turned to "compulsive hot bathing behaviour" to relieve the symptoms but he was not cured until he gave up smoking cannabis altogether.

Adelaide-based drug expert and emergency ward doctor, Dr David Caldicott, said he had seen three cases of the illness and it was possibly also under-reported by sufferers.

"We're probably seeing the tip of the iceberg in the emergency departments, it's probably far more common but far milder (in the broader community)," he said.

Little was known about how cumulative cannabis use could lead to vomiting and, particularly, why sufferers would find some relief in hot bathing, Dr Caldicott also said.

"That's a distinct and unanimously recurrent feature of this condition, and we don't know why," he said.

"Grown men, screaming in pain, sweating profusely, vomiting every 30 seconds and demanding to be allowed to use the shower. It's a very dramatic presentation."

Dr Caldicott said the condition had been identified in a small number of cannabis users "but in the medical community it is now considered to be a real condition".

The National Cannabis Prevention and Information Centre, based at the University of NSW, is taking a more conservative approach.

Centre director Jan Copeland said more cases would need to emerge before it could be considered a new syndrome linked to chronic cannabis use.

"It is not unusual for there to be significant mental and physical health complications with this level of cannabis use," Professor Copeland said.

- AAP