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“Cannabis hyperemesis” causation questioned
  1. A Byrne1,
  2. R Hallinan1,
  3. A Wodak2
  1. 1Byrne Surgery, Sydney, Australia
  2. 2St Vincent’s Hospital, Darlinghurst, New South Wales, Australia
  1. Correspondence to:
    Dr A Byrne
    Byrne Surgery, 75 Redfern St, Redfern, 2016, Sydney, Australia; ajbyrne{at}
  1. J H Allen3,
  2. G M de Moore4,
  3. R Heddle5,
  4. J C Twartz6
  1. 3Department of Medicine, Mt Barker Hospital, Mt Barker, South Australia, Australia
  2. 4Department of Psychiatry, Westmead Hospital, Westmead, New South Wales, Australia
  3. 5Department of Gastroenterology, Repatriation General Hospital, Daw Park, South Australia, Australia
  4. 6Department of Medicine, Ashford Hospital, Ashford, South Australia, Australia

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The authors describe a number of cases of a bizarre syndrome of severe vomiting, abdominal symptoms leading to dehydration, in combination with repetitive bathing behaviour (Gut 2004;53:1566–70). They have concluded that these symptoms are due to cannabis use.

Cannabis has been consumed for many centuries and is currently used by millions of people in many countries. It is hard to believe that a distinctive syndrome caused by cannabis has never been noted before by users or clinicians.

The authors assert that cannabis laws are particularly liberal in South Australia. Four Australian jurisdictions now have a cannabis expiation notice system which South Australia first introduced in 1986. The other four Australian jurisdictions have variations on a bond system. Several European countries have far more lenient legislative arrangements. After over a generation of liberalisation of cannabis laws in many countries around the world, there is little evidence of a subsequent increase in cannabis use.

In a comparative study using the same methodology, the prevalence of cannabis use in more “liberal” Amsterdam was lower than in the more “punitive” San Francisco.1

The title of the paper, “Cannabinoid hyperemesis” is unduly presumptive. Some of these cases appeared to improve with abstinence and then relapsed when patients were “rechallenged” with cannabis, but neither the patients nor the authors appear to have been blinded in the rechallenge. The proposed biological explanation is weak.

We suggest that alternative explanations need to be sought for these cases. This syndrome should not be accepted as being caused by cannabis without additional reports and other evidence.


Authors’ reply

We would like to thank Byrne et al for their interest in our paper (Gut 2004;53:1566–70). It should be noted that we undertook an observational study by necessity. Cannabis is an illegal drug and double blind control trials with illicit substances are prohibited and unethical. The assertion that cannabis has been “consumed for many centuries” needs to be tempered with the fact that cannabis has been grossly under-researched clinically and, as we have shown with this syndrome, nowhere near fully understood in its neuropharmacology or paradoxical actions. Since publication of our article, other authors have published similar findings to ours and drawn the same conclusions.1



  • Dr Wodak is President of the Australian Drug Law Reform Foundation which supports the taxation and regulation of cannabis.


  • Conflict of interest: None declared.