Background: Cannabinoid hyperemesis syndrome is a variant of cyclical vomiting syndrome in a context of chronic cannabis usage. Our aim was to compare French cases to those identified in the international literature in order to further our knowledge of the clinical criteria, pathophysiology and treatments for cannabinoid hyperemesis syndrome.
Methods: We analysed cases reported in the international literature up to 30 June 2017, obtained from the MEDLINE, PsycINFO and The Cochrane Library databases; we selected relevant articles based on title and abstract. We also analysed cases of cannabinoid hyperemesis syndrome reported to the French addictovigilance network.
Results: A systematic search through the three databases enabled us to identify 137 articles. Finally, 55 articles were selected as they involved reported cases. In total, 113 cases were reported in these 55 articles. We were thus able to analyse 29 reported French cases of cannabinoid hyperemesis syndrome. Cannabinoid hyperemesis syndrome mainly affects young male subjects who have been smoking cannabis daily for several years. Taking hot baths or showers is the most effective means of relieving the symptoms, while antiemetics and dopamine antagonists do not appear to effective for relieving nausea and vomiting.
Conclusions: French cases display the same characteristics as the cases identified in the international literature. The pathophysiology of cannabinoid hyperemesis syndrome is unclear and several hypotheses have been put forward in the literature. We have only begun to characterise the syndrome, though there is an outbreak of cannabinoid hyperemesis syndrome in France.

Highlights:
We have only just begun to characterize cannabinoid hyperemesis syndrome.
French cases display the same characteristics as the international literature cases.
There is a cannabinoid hyperemesis syndrome outbreak in France.