Rare but relevant: Cannabinoid hyperemesis syndrome.

Cannabinoid hyperemesis syndrome (CHS) is a (probably) rare syndrome that occurs in frequent and chronic cannabis users. It is characterised by cyclical vomiting and gastrointestinal symptoms. CHS is frequently misdiagnosed resulting in extensive investigations and delayed diagnosis and treatment. Standard anti-emetic treatments are typically not effective, and no standardised treatment protocol exists for CHS. Bathing or showering in hot water is often reported to relieve symptoms. Little is known of the aetiology of CHS as the literature is predominantly informed by case reports and chart reviews. Similarly, little is known of the demographics and cannabis use patterns of those who develop CHS. The number of CHS cases globally appears to have risen following liberalisation of cannabis regulation and access in some countries, underscoring the need for wider recognition of CHS in emergency care and by the wider public.