“I keep getting these awful vomiting attacks — the only thing that helps is standing in a really hot shower for hours”

CANNABIS HYPEREMESIS SYNDROME (CHS) is recurrent/CYCLICAL severe nausea, vomiting and abdominal pain in a chronic/heavy CANNABIS user, classically RELIEVED by HOT SHOWERS/BATHS (compulsive hot bathing), often after multiple normal prior investigations and A&E attendances — the hot-bathing relief being a highly characteristic clue. CHS is frequently MISSED because clinicians do not ask about cannabis, so take a non-judgemental substance history (frequency, duration, amount), normalising the question — without it the diagnosis is repeatedly missed despite extensive work-ups. Exclude other causes of cyclical/recurrent vomiting and red flags: GI causes (obstruction, peptic disease, gallstones, pancreatitis), raised intracranial pressure, metabolic/endocrine causes (DKA, Addisonian crisis, hypercalcaemia), cyclical vomiting syndrome, and pregnancy in women — reassuringly normal previous investigations plus the hot-bath/cannabis pattern support CHS, but red flags must be screened. The critical message is that the ONLY definitive treatment is CANNABIS CESSATION: symptoms resolve with abstinence and recur with continued use, so explain this clearly and supportively as the central, often-resisted point; standard antiemetics are frequently poorly effective (BNF), and acute supportive care includes IV fluids and, in acute/hospital settings, topical capsaicin to the abdomen (an unlicensed use) and other drug treatment chosen by the hospital team. Recovery with sustained abstinence may take weeks or longer. Provide harm-reduction and cessation support (motivational approach and referral to drug services, NICE CG51) for a difficult behaviour change, framing cessation as the cure rather than moralising, and warn that cannabis withdrawal (irritability, poor sleep, low appetite, low mood) can occur in the first weeks. Safety-net dehydration and electrolyte disturbance including acute kidney injury (urgent care if unable to keep fluids down) and scalds from very hot water, and cover driving: it is illegal to drive with cannabis in the blood above the specified limit or while impaired, and persistent misuse of or dependence on cannabis must be notified to the DVLA, with driving stopped. Observations and the abdomen are examined face to face, as they cannot be assessed on video. The skill is recognising the pattern (cyclical vomiting + hot-bath relief + cannabis), asking about cannabis non-judgementally, excluding red flags, and delivering the cessation message with support.