›Dextrose suppresses ketogenesis and shortens the episode in the migraine and mitochondrial phenotypes
›Match the sodium concentration to the measured serum sodium and the osmolality workup, avoiding hypotonic fluid when inappropriate antidiuretic hormone secretion is suspected
›Hypoglycemia correction
›Adult — 10 percent dextrose 100 to 250 ml intravenous, or 25 percent dextrose 50 ml, then recheck in 15 to 30 minutes
›Child — 10 percent dextrose 2 to 5 ml/kg intravenous bolus, then a maintenance dextrose infusion
›Verify against current pediatric guideline before use
›Thiamine before sustained dextrose
›Thiamine 100 mg intravenous before or with the first dextrose in prolonged vomiting, malnutrition, pregnancy, or alcohol use
›Use 200 to 500 mg intravenous three times daily if Wernicke encephalopathy is suspected
›Fluid-related pitfalls
›Over-rapid correction of hyponatremia risks osmotic demyelination — cap the rise at 8 mmol/l in 24 hours
›Large volumes of salt-poor fluid can worsen hyponatremia and precipitate a seizure, especially in the Sato variant
›Reassess the lungs during resuscitation in cardiac or renal comorbidity to avoid overload
›Hypotension that does not respond to volume is not part of cyclic vomiting syndrome — search for sepsis, hemorrhage, or adrenal crisis before starting a vasopressor
›Potassium
›Oral potassium chloride 40 to 80 mmol/day in divided doses when tolerated
›Intravenous potassium chloride when oral is not possible or potassium is under 3.0 mmol/l
›Peripheral line no faster than 10 mmol/h; central line with continuous cardiac monitoring no faster than 20 mmol/h
›Recheck serum potassium every 2 to 4 hours during active repletion
›Target 4.0 to 4.5 mmol/l while QT-prolonging antiemetics are in use, and a lower target with slower rates in oliguric chronic kidney disease
›Magnesium
›Magnesium sulfate 2 g intravenous over 1 to 2 hours for hypomagnesemia or ongoing QT concern
›Repeat to keep serum magnesium above 0.8 mmol/l
›Halve the dose and recheck early in significant renal impairment
›Phosphate
›Replace when phosphate is under 0.3 mmol/l or the patient is symptomatic, using an intravenous phosphate salt with monitoring of calcium and renal function
›Acid-base correction
›The metabolic alkalosis of gastric loss corrects with sodium chloride and potassium chloride repletion, not with acid administration
›A rising anion gap or a new acidosis during treatment should trigger reassessment for ketoacidosis, an inborn error of metabolism, sepsis, or ischemia
›Ondansetron
›4 mg intravenous or orally dispersible every 8 hours as needed
›Maximum single dose 8 mg and maximum 16 mg in 24 hours by the intravenous route
›A single 16 mg intravenous dose is contraindicated because of QT prolongation
›Obtain a baseline ECG and correct potassium and magnesium before repeat dosing
›Metoclopramide
›10 mg intravenous every 6 hours as needed, infused over at least 3 minutes, for up to 5 days
›Contraindicated in bowel obstruction, perforation, or GI hemorrhage
›Extrapyramidal reactions and akathisia are more common in young patients and at higher cumulative dose; treat dystonia with an anticholinergic or diphenhydramine
›Reduce the dose in renal impairment
›Prochlorperazine
›5 to 10 mg intravenous every 6 to 8 hours as needed, maximum 40 mg/day
›Avoid in children under 2 years or under 9 kg
›Sedation, hypotension, dystonia, and QT prolongation
›Promethazine
›12.5 to 25 mg every 4 to 6 hours, deep intramuscular or highly diluted into a running intravenous line
›Severe tissue injury and limb ischemia can follow perivascular or intra-arterial injection
›Contraindicated under 2 years of age because of fatal respiratory depression
›Combination and sequencing
›Combine a 5-HT3 antagonist with a dopamine antagonist rather than stacking two dopamine antagonists
›Track the total QT-prolonging burden across all agents and repeat the ECG
Abortive therapy and sedation to break the episode
›Triptans for the migraine phenotype, best given in the prodrome
›Sumatriptan 6 mg subcutaneous, may repeat once after 1 hour, maximum 12 mg in 24 hours
›Intranasal sumatriptan 20 mg, may repeat after 2 hours, maximum 40 mg in 24 hours, when the subcutaneous route is refused
›Oral sumatriptan 50 to 100 mg, maximum 200 mg in 24 hours, if the patient can swallow and retain it
›Contraindicated in ischemic heart disease, prior myocardial infarction, uncontrolled hypertension, hemiplegic or basilar migraine, and within 24 hours of an ergot or another triptan
›Aprepitant as a neurokinin-1 antagonist for refractory nausea
›125 mg orally on day 1, then 80 mg on days 2 and 3, for an acute episode when it can be retained
›Weight-based dosing in children per specialist guidance
›Interacts with warfarin, hormonal contraception, and CYP3A4 substrates
›Benzodiazepines for sedation and their anxiolytic and antiemetic effect
›Lorazepam 0.5 to 1 mg intravenous every 6 hours as needed in adults, titrated to light sedation
›Pediatric lorazepam 0.05 mg/kg intravenous, maximum 2 mg per dose
›Verify against current pediatric guideline before use
›Additive respiratory depression and hypotension with antipsychotics, and oversedation can mask an evolving abdominal or neurologic process — monitor continuously and reassess the abdomen
›Antipsychotics to terminate a refractory episode
›Olanzapine 2.5 to 5 mg orally dispersible, intramuscular, or intravenous, repeated cautiously
›Haloperidol 2.5 to 5 mg intravenous or intramuscular, with useful evidence in cannabinoid hyperemesis syndrome
›Pediatric and adolescent dosing only with specialist input
›Droperidol 0.625 to 1.25 mg intravenous, titrated
›Requires a baseline and post-dose ECG because of the QT boxed warning
›Do not combine parenteral droperidol and haloperidol in the same episode
›Chlorpromazine 25 mg intravenous in adults, classically paired with diphenhydramine 25 to 50 mg to prevent dystonia
›Marked sedation and orthostatic hypotension — give a fluid bolus first and keep the patient supine
›Adjuncts
›Diphenhydramine 25 to 50 mg intravenous every 6 hours in adults for vestibular symptoms and as dystonia prophylaxis with dopamine antagonists
›Dexamethasone 8 to 10 mg intravenous once as an antiemetic adjunct in a refractory episode
›A parenteral triptan plus lorazepam plus an antiemetic is a common effective bundle in the emetic phase
Analgesia, opioid avoidance, and cannabinoid hyperemesis overlap
›Preferred analgesia
›Acetaminophen 1 g orally or intravenously every 6 hours, maximum 3 g/day
›Ketorolac 15 to 30 mg intravenous every 6 hours, maximum 120 mg/day, for no more than 5 days
›Avoid with acute kidney injury, significant volume depletion until rehydrated, GI bleeding, or in the last trimester of pregnancy
›Why opioids are avoided
›Opioids slow gastric emptying, worsen nausea, and promote a narcotic bowel and opioid-induced hyperalgesia that perpetuate the cycle
›Opioid analgesia also masks an evolving surgical abdomen in a patient who is being observed rather than imaged
›If an opioid is unavoidable for another indication, use the smallest effective dose for the shortest time and document the reason
›Cannabinoid hyperemesis syndrome overlap, assumed when cannabis use is daily
›Topical capsaicin 0.025 to 0.075 percent cream applied to the abdomen or back every 4 to 6 hours
›Warn about local burning, keep it away from eyes and mucous membranes, and have the patient wash hands after application
›Haloperidol or droperidol at the doses above are more effective than ondansetron for this phenotype
›A hot shower or bath gives short-lived relief and supports the diagnosis but is not a treatment plan
›Definitive step for the cannabis phenotype
›Complete and sustained cannabis cessation is the only reliably curative measure and resolves episodes over weeks to months
›Provide written cessation resources and arrange addiction-medicine follow-up before discharge
Prophylaxis and the non-responding patient
›Continue or restart home prophylaxis
›Do not stop a patient's established prophylactic agent during an acute admission unless it is contraindicated
›Document the regimen, adherence, and any recent gap or dose change
›Adult prophylactic options to initiate with specialist follow-up
›Amitriptyline 10 to 25 mg at night, titrated toward 50 to 100 mg or about 1 mg/kg, with a baseline ECG for the QT interval
›Topiramate 25 mg at night titrated to about 100 mg/day
›Teratogenic, with oral cleft and hypospadias risk — avoid in pregnancy and pair with reliable contraception
›Propranolol 10 to 20 mg twice daily
›Avoid in asthma, and use cautiously in diabetes because it blunts hypoglycemia awareness
›Mitochondrial supplements — coenzyme Q10 100 mg three times daily, riboflavin 100 to 400 mg/day, and L-carnitine
›Aprepitant 80 to 125 mg every other day as add-on prophylaxis in refractory disease under specialist care
›The non-responding patient — a structured reassessment
›Re-verify the diagnosis — repeat the abdominal and neurologic examination and review whether imaging for obstruction, ischemia, or a central lesion is complete
›Recheck potassium, magnesium, sodium, glucose, and the acid-base pattern — an unexpected acidosis or persistent hypokalemia changes the plan
›Confirm each drug was given at an adequate dose and route and that vomiting did not prevent absorption of oral agents
›Screen again for ongoing cannabis use and for occult opioid use
›Escalate to scheduled combination therapy, a benzodiazepine or antipsychotic in a monitored bed, and admission
›Involve gastroenterology, neurology, and pain psychology early rather than repeating single-agent rescue attempts