← Full nausea and vomiting algorithm
Reasoning GP · Diagnostic Compass · decision tree

Nausea and vomiting1 PAGE

Nausea or vomiting in an adult: is it dangerous, how urgent, and what is the likely cause?
NICE NG12 (Apr 2026) · CG184 · NG127
NG240 · NG243 · RCOG GTG 69 (2024) · MHRA
Reviewed Oct 2026 · next review Apr 2027
Applies to: adults, acute <1 week or chronic >1 month, face to face or remote. Not children, ongoing pregnancy or palliative care. The company the vomiting keeps tells you the cause; pregnancy test whenever pregnancy is possible.
Vomiting presents

Peritonism; drowsy, confused or shocked; acute stroke · Thunderclap headache (SAH); meningism, fever, non-blanching rash · Suspected ACS: chest pain; silent MI when older or diabetic · Severe DKA: Kussmaul, shock, altered consciousness · Adrenal crisis: low BP, low Na, high K, steroids stopped or vomited · Haematemesis with fresh blood, shock or cirrhosis · Pregnant with seizure, collapse or neuro signs

Emergency?
YES
CALL 999
Adrenal crisis: hydrocortisone 100 mg IM/IV. Meningococcal strongly suspected: benzylpenicillin 1.2 g IM/IV (or ceftriaxone) unless it delays transfer. ACS: no wait for ECG.
NO

Obstruction, appendicitis, pancreatitis, cholecystitis, GI bleed → surgical · Raised ICP: headache worse on waking or lying, papilloedema → neuro · Ketones ≥3.0 mmol/L; no fluid kept down >24 h, AKI, low Na or K · Angle closure: red painful eye, haloes → ophthalmology · Pregnant: fluids or antiemetics not kept down, weight loss ≥5%; >20 weeks → obstetric · Cancer: dysphagia; ≥55, weight loss + upper pain, reflux or dyspepsia

Same day or cancer pathway?
YES
SAME DAY · CANCER PATHWAY
All same day. Obstruction: nil by mouth, no prokinetic. Pregnant BP ≥160/110: admit. ≥60, vomiting + weight loss: consider urgent direct-access CT.
NO
Which pattern?
Acute GI<1 week, diarrhoea
  1. Gastroenteritis: fluids, ORS sips.
  2. Recent antibiotics: C. difficile.
  3. Vomiting at 48 h: reassess.
Vestibularvertigo, nystagmus, positional
  1. Cyclizine 50 mg TDS or prochlorperazine; not ondansetron.
  2. Dix-Hallpike, head impulse, gait.
  3. Cannot stand or HINTS abnormal: stroke assessment (NG127).
Drug, metabolicGLP-1, opioid, digoxin, calcium
  1. Reduce or stop; correct calcium, Na, K.
  2. Cannabis hyperemesis: stop cannabis.
  3. Digoxin toxicity, hypercalcaemia: same-day medical.
Stasis, chronicundigested food 1–3 h after meals
  1. Obstruction excluded: metoclopramide 10 mg TDS, ≤5 days.
  2. Migraine: antiemetic + triptan.
  3. Gastroparesis, cyclical, functional: gastroenterology.
EVERY PATIENT

Tests that change management

  • Pregnancy test whatever the contraception; diabetes: glucose + ketones; ECG if older or diabetic.
  • Persistent or unwell: FBC, U&E, LFTs, glucose; calcium, CRP, TFTs, lipase if indicated.
  • ≥55 with weight loss, reflux, dyspepsia: consider non-urgent direct-access OGD.
  • Not: abdominal X-ray, outpatient scan for obstruction.

Safety-net · follow up

  • 999: hard tummy, vomiting blood, sudden severe headache, drowsy, chest pain, fit, non-fading rash, sudden weakness.
  • Today: no fluid kept down 24 h, little urine, dizzy standing, headache worse lying flat, raised ketones.
  • 48–72 h review; failure → reassess the diagnosis first. Written sick-day rules; stop dates for antiemetics.
Never: Reassure by diarrhoea, pain eased by vomiting, or a normal glucose on an SGLT2 inhibitor · Call it "just vomiting" when older or diabetic, or "a virus" at 48 h · Give a prokinetic in obstruction, or an antiemetic instead of a pregnancy test
Reasoning GP · Nausea and vomiting · decision tree · v1.0 · Oct 2026 · Full algorithm: gpreasoning.uk/tools/algorithms/nausea-vomiting-adults.htmlDecision support, not a substitute for clinical judgement. Check doses in the SPC and your local formulary.