Nausea & Vomiting

at the bedside

airway, breathing, circulation; full vitals, glucose; IV access if not keeping fluids down
what is coming up → food, bile, feculent, blood or coffee grounds; last stool and flatus; distension
how dry → mucosa, postural drop, urine output
not the gut → headache or neurology, chest pain, pregnancy, new drug, high glucose: ask before the antiemetic

escalate now if

bilious or feculent vomiting, distension, no flatus, or absent bowel sounds → obstruction, surgery
severe abdominal pain or peritonism → abdominal pain
blood or coffee grounds → GI bleed
headache, drowsiness, new neurology or vomiting without nausea → raised intracranial pressure → headache, neurological deficit
glucose high with ketones, or Kussmaul breathing → DKA → hyperglycemia
hypotension, K⁺ < 3.0, or AKI from the losses → fluids and electrolytes, hypotension
chest pain, diaphoresis, elderly or diabetic → ECG now, inferior MI vomits → chest pain

obstruction or ileus → bilious or feculent, distension, no flatus; adhesions, hernia, opioids, post-op
drugs → opioids, antibiotics, chemotherapy, digoxin, metformin, iron, new anything this week
infection → gastroenteritis, pyelonephritis, pneumonia, sepsis; fever decides
abdominal → pancreatitis, cholecystitis, hepatitis, peptic ulcer, GI bleed → abdominal pain
metabolic → DKA, uremia, hypercalcemia, hyponatremia, adrenal insufficiency
neurological → raised intracranial pressure, migraine, vertigo (vestibular neuritis, BPPV), posterior circulation stroke
cardiac → inferior MI, especially elderly or diabetic
pregnancy → nausea and vomiting of pregnancy; hyperemesis if weight loss, ketosis, electrolyte derangement

vomit → content, volume, timing after meals, projectile, with or without nausea
symptoms → pain and where, fever, diarrhea, last stool and flatus, headache, vertigo, chest pain, thirst and polyuria
history → previous surgery, diabetes, kidney disease, IHD, migraine, alcohol, last period
drug chart → opioids, antibiotics, chemotherapy, digoxin, metformin, QT-prolonging drugs already on board
exam → hydration; distension, tenderness, hernial orifices, bowel sounds; fundi and neurology if headache; nystagmus if vertigo

RFT, Mg, glucose, VBG → dehydration, K⁺ and acid-base from the losses, DKA
CBC, CRP, LFT, lipase → infection, biliary or pancreatic cause
ECG, troponin → chest pain, elderly or diabetic; QTc before ondansetron if at risk
β-hCG → every woman of reproductive age
abdominal X-ray → obstruction suspected; CT abdomen → obstruction confirmed or peritonism; CT head → headache, neurology, or vomiting without nausea
urinalysis, cultures → fever → fever

obstruction suspected

NPO, IV fluids, correct K; NG tube if vomiting, distended or high-grade; surgery now → abdominal pain
no metoclopramide in obstruction or perforation

fluids and electrolytes

IV balanced crystalloid if dry or not tolerating oral; 500 mL bolus if hypotensive, then maintenance with K
replace K and Mg → potassium, magnesium; vomiting causes a hypochloremic alkalosis, saline corrects it
thiamine before glucose → prolonged vomiting, alcohol or malnutrition: thiamine 200–300 mg IV first

antiemetics: choose by cause

ondansetron 4–8 mg IV/PO up to TDS → first choice for most; check QTc if long QT, heart failure, low K or Mg, or other QT drugs; constipating
metoclopramide 10 mg IV/PO TDS → gastroparesis, migraine, opioid nausea; not in obstruction, perforation or Parkinson disease; max 5 days; half dose in renal impairment
cyclizine 50 mg PO/IM/slow IV TDS → vertigo, motion, raised pressure; anticholinergic: caution in the elderly, glaucoma, prostatic enlargement, heart failure
haloperidol 0.5–1 mg PO/SC → opioid or metabolic nausea, palliative patients; QT
dexamethasone 4–8 mg IV → chemotherapy or raised intracranial pressure, with the treating team
second agent from a different class before a bigger dose of the first; PPI only if reflux, ulcer or bleeding is suspected

pregnancy

pyridoxine 10–25 mg PO TDS ± doxylamine first; then metoclopramide or ondansetron; hyperemesis (ketones, weight loss, electrolytes) → IV fluids with thiamine, obstetrics

treat the cause → stop or switch the drug; infection → fever; DKA → hyperglycemia; uremia → acute kidney injury; hypercalcemia → calcium
hand over → cause, antiemetic given, fluids and electrolytes, NG tube or not, review time

source	type
FDA ondansetron QT safety communication; metoclopramide tardive dyskinesia boxed warning	regulatory / safety update
ACOG 2018 nausea and vomiting of pregnancy practice bulletin	international guideline
ACG 2024 acute pancreatitis guideline	international guideline

Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.

free the on-call checklist covers the whole shift on one printable page.

studying for the IM exam? the IM Rapid Review covers this in the same format. see the sample chapter.

reviewed Jul 2026updated Oct 2026file complaint/nausea-and-vomiting