1. Physiology and vomiting reflex
2. Causes and clinical classification
3. History and examination
4. Red flags and assessment of severity
5. Investigations
6. Initial stabilization and fluids/electrolytes
7. Antiemetic pharmacology
8. Cause-specific management
9. Complications and prevention
10. Important exam cases, differentials, and viva points

1. Physiology and vomiting reflex
2. Causes and clinical classification
3. History and examination
4. Red flags and assessment of severity
5. Investigations
6. Initial stabilization and fluids/electrolytes
7. Antiemetic pharmacology
8. Cause-specific management
9. Complications and prevention
10. Important exam cases, differentials, and viva points

1. Complete exam note: structured final-year notes on vomiting
2. Approach and management: emergency assessment, fluids, investigations, treatment algorithm
3. Antiemetic drugs: classes, mechanisms, indications, adverse effects, contraindications
4. Causes and diagnosis: differential diagnosis with clinical clues
5. Exam cases and viva: short cases, long-answer framework, common questions

1. Definitions and differentiation from regurgitation/rumination
2. Physiology of the emetic reflex
3. Causes and differential diagnosis
4. Clinical assessment, red flags, history, and examination
5. Investigations
6. Emergency stabilization, fluids, and electrolyte correction
7. Antiemetic drugs and their adverse effects
8. Cause-specific management
9. Complications
10. Chronic vomiting syndromes, pregnancy, and exam cases

1. Physiology and vomiting reflex
2. Causes and clinical classification
3. History and examination
4. Red flags and assessment of severity
5. Investigations
6. Initial stabilization and fluids/electrolytes
7. Antiemetic pharmacology
8. Cause-specific management
9. Complications and prevention
10. Important exam cases, differentials, and viva points

1. Complete exam note: structured final-year notes on vomiting
2. Approach and management: emergency assessment, fluids, investigations, treatment algorithm
3. Antiemetic drugs: classes, mechanisms, indications, adverse effects, contraindications
4. Causes and diagnosis: differential diagnosis with clinical clues
5. Exam cases and viva: short cases, long-answer framework, common questionsA complete final-year note on vomiting is a large topic. The exam-oriented map is:
6. Definitions and differentiation from regurgitation/rumination
7. Physiology of the emetic reflex
8. Causes and differential diagnosis
9. Clinical assessment, red flags, history, and examination
10. Investigations
11. Emergency stabilization, fluids, and electrolyte correction
12. Antiemetic drugs and their adverse effects
13. Cause-specific management
14. Complications
15. Chronic vomiting syndromes, pregnancy, and exam cases

1. Definitions

• Nausea: unpleasant subjective sensation of an urge to vomit, often associated with salivation, sweating, pallor, anorexia, and anxiety.
• Retching: repeated spasmodic respiratory and abdominal contractions against a closed glottis, without expulsion of gastric contents.
• Vomiting / emesis: forceful expulsion of gastric or intestinal contents through the mouth.
• Regurgitation: effortless return of gastric or esophageal contents to the mouth, without nausea, retching, or forceful abdominal contraction.
  • Esophageal regurgitation: recently eaten, undigested food, as in achalasia.
  • Gastric regurgitation: sour material, often with heartburn, as in GERD.
• Rumination syndrome: repetitive, effortless regurgitation of recently ingested food, usually soon after meals, which may be rechewed, reswallowed, or spat out.

2. Physiology of vomiting

Main afferent inputs

Important receptors

• 5-HT3 (serotonin): vagal afferents and CTZ
• D2 (dopamine): CTZ
• H1 histamine and M1 muscarinic: vestibular pathway
• NK1 (substance P): central vomiting pathways
• Cannabinoid receptors: modulate emetic pathways

Sequence

1. Nausea, salivation, pallor, tachycardia
2. Retching with closure of glottis
3. Relaxation of lower esophageal sphincter
4. Diaphragm and abdominal-wall contraction
5. Expulsion of gastric contents while airway is protected by glottic closure

3. Causes of vomiting

A. Gastrointestinal causes

Acute causes

• Acute gastroenteritis and food poisoning
• Gastritis, peptic ulcer disease
• Acute appendicitis
• Acute cholecystitis or biliary colic
• Acute pancreatitis
• Hepatitis
• Intestinal obstruction
• Perforated viscus with peritonitis
• Mesenteric ischemia
• Diverticulitis
• Incarcerated hernia
• Gastric volvulus

Mechanical obstruction

Chronic GI causes

• Peptic-ulcer-related gastric outlet obstruction
• Gastric cancer
• Gastroparesis, especially diabetic
• Chronic intestinal pseudo-obstruction
• Crohn disease with stricture
• Coeliac disease
• Achalasia or other esophageal motor disorders
• Functional dyspepsia
• Rumination syndrome

B. CNS and vestibular causes

• Raised intracranial pressure due to tumor, hemorrhage, hydrocephalus, abscess
• Meningitis, encephalitis
• Migraine
• Posterior circulation stroke
• Vertigo, vestibular neuritis, labyrinthitis, Ménière disease
• Head injury
• Motion sickness

C. Metabolic and endocrine causes

• Diabetic ketoacidosis
• Uremia
• Adrenal insufficiency / Addisonian crisis
• Hypercalcemia
• Hyponatremia
• Thyrotoxicosis
• Acute intermittent porphyria
• Severe metabolic acidosis
• Pregnancy, especially hyperemesis gravidarum

D. Drugs, toxins, and substances

• Opioids
• NSAIDs
• Digoxin toxicity
• Theophylline toxicity
• Antibiotics, especially macrolides
• Metformin
• Levodopa and dopamine agonists
• Chemotherapy
• Radiotherapy
• Alcohol intoxication or withdrawal
• Organophosphate poisoning
• Salicylate toxicity
• Iron poisoning
• Cannabis: cannabinoid hyperemesis syndrome
• Ingestion of toxins or corrosives

E. Infection and systemic disease

• Sepsis
• Malaria
• COVID-19 or influenza-like viral illness
• Pyelonephritis
• Myocardial infarction, especially inferior-wall MI
• Renal colic
• Acute glaucoma
• Testicular torsion
• Severe pain of any cause

F. Psychiatric and functional causes

• Anxiety disorders
• Eating disorders, especially bulimia nervosa
• Functional vomiting
• Cyclic vomiting syndrome
• Psychogenic vomiting
• Rumination syndrome

4. Clinical assessment

A. Immediate priorities

Assess urgently for:

• Shock or severe dehydration
• Reduced consciousness and aspiration risk
• Acute abdomen or peritonitis
• GI obstruction
• GI bleeding
• Raised intracranial pressure
• DKA, uremia, adrenal crisis, or sepsis
• Toxic ingestion
• Pregnancy-related hyperemesis

Red flags

• Hematemesis or coffee-ground vomitus
• Bilious vomiting
• Feculent vomiting
• Severe abdominal pain, guarding, rigidity, or rebound tenderness
• Marked abdominal distension with obstipation
• Hypotension, oliguria, syncope, confusion
• Fever with neck stiffness, rash, or photophobia
• Severe headache, focal neurologic deficit, altered consciousness, papilledema
• Persistent vomiting with weight loss or anemia
• New vomiting in older age
• Vomiting after head injury
• Poisoning, overdose, or suspected toxic ingestion

B. History

Characterize the vomiting

• Onset: acute or chronic
• Frequency and volume
• Relation to meals
• Projectile or non-projectile
• Contents:
  • Undigested food: achalasia, gastroparesis, gastric outlet obstruction
  • Bilious: distal duodenal or small-bowel obstruction
  • Feculent: distal intestinal obstruction
  • Blood or coffee-ground material: upper GI bleeding
• Associated retching
• Relief after vomiting
• Relation to posture, motion, stress, migraine, or menstruation

Associated symptoms

Relevant background

• Medication review, including prescribed, OTC, herbal, recreational drugs
• Alcohol and cannabis use
• Diabetes, kidney disease, migraine, malignancy
• Previous abdominal surgery or hernia
• Previous similar attacks
• Weight loss, dysphagia, early satiety
• Travel, food exposure, sick contacts
• Menstrual and obstetric history
• Psychological stress, eating disorder behavior, self-induced vomiting

C. Examination

General examination

• Hydration: dry tongue, poor skin turgor, thirst
• Pulse, BP including postural BP, temperature, respiratory rate
• Mental status
• Weight and nutritional state
• Pallor, jaundice, lymphadenopathy
• Signs of endocrine disease
• Peripheral edema or features of chronic organ failure

Abdominal examination

• Distension
• Scars and hernias
• Bowel sounds:
  • High-pitched/tinkling: mechanical obstruction
  • Silent abdomen: ileus or peritonitis
• Tenderness and localization
• Guarding, rigidity, rebound tenderness
• Palpable mass or organomegaly
• Succussion splash: retained gastric contents, possible gastric outlet obstruction
• Rectal examination when obstruction, bleeding, impaction, or pelvic pathology is suspected

Neurologic examination

• Consciousness and cognition
• Meningism
• Fundus for papilledema
• Cranial nerves, nystagmus
• Cerebellar signs
• Focal deficits

5. Investigations

Basic investigations in significant, persistent, or unexplained vomiting

• CBC
• Serum electrolytes: sodium, potassium, chloride, bicarbonate
• Urea, creatinine
• Blood glucose
• Liver-function tests
• Serum amylase/lipase if pancreatitis possible
• Urinalysis, ketones
• Urine or serum beta-hCG in all patients who may be pregnant
• ECG, particularly if electrolyte disturbance, cardiac symptoms, or QT-prolonging antiemetics are being considered
• Venous or arterial blood gas in severe illness, DKA, sepsis, poisoning, or major acid-base disturbance

Imaging and special tests

6. Complications

A. Fluid and electrolyte complications

• Dehydration
• Hypovolemia and shock
• Acute kidney injury
• Hypochloremic, hypokalemic metabolic alkalosis
• Hyponatremia
• Hypomagnesemia
• Cardiac arrhythmias
• Muscle weakness, cramps, tetany

B. Mechanical and respiratory complications

• Aspiration pneumonitis or aspiration pneumonia
• Mallory-Weiss tear causing hematemesis
• Boerhaave syndrome: spontaneous esophageal rupture after forceful vomiting
• Pneumomediastinum
• Dental enamel erosion
• Parotid enlargement in recurrent self-induced vomiting

C. Nutritional complications

• Weight loss and protein-calorie malnutrition
• Thiamine deficiency, especially in prolonged vomiting and hyperemesis gravidarum
• Wernicke encephalopathy if carbohydrate is given before thiamine in a severely malnourished person
• Vitamin and trace-element deficiencies

7. Management

A. General principles

1. Stabilize the patient
2. Assess aspiration risk
3. Correct fluid and electrolyte deficits
4. Identify surgical, neurologic, metabolic, infectious, toxic, and pregnancy-related causes
5. Give an antiemetic appropriate to the cause
6. Treat the underlying disease
7. Monitor response and reassess frequently

B. Immediate supportive management

If unstable or severely dehydrated

• Keep nil by mouth initially if active vomiting, obstruction, or surgery is possible.
• Position laterally if drowsy or vomiting to reduce aspiration.
• Give oxygen if hypoxemic.
• Obtain IV access.
• Give isotonic IV crystalloid, commonly 0.9% saline when chloride depletion/metabolic alkalosis is likely.
• Monitor BP, pulse, urine output, mental state, and serial electrolytes.
• Insert urinary catheter in shock, severe dehydration, or need for accurate output monitoring.
• Consider NG tube decompression for bowel obstruction, gastric outlet obstruction, severe distension, or persistent large-volume vomiting.
• Correct potassium after ensuring adequate renal function and urine output.
• Give thiamine before glucose-containing fluids in malnutrition, alcoholism, or prolonged vomiting.

If mild and no danger signs

• Oral rehydration solution in small frequent sips
• Advance diet gradually as tolerated
• Avoid alcohol, excessive fat, and trigger foods
• Treat the identified cause

8. Antiemetic drugs

A. 5-HT3 antagonists

Drugs

• Ondansetron
• Granisetron
• Palonosetron

Uses

• Acute undifferentiated vomiting
• Gastroenteritis
• Postoperative nausea/vomiting
• Chemotherapy- or radiotherapy-induced nausea/vomiting

Adverse effects

• Headache
• Constipation
• QT prolongation
• Rare serotonin syndrome, particularly with serotonergic drugs

B. Dopamine D2 antagonists / prokinetics

Metoclopramide

• D2 antagonist in CTZ
• 5-HT4 agonist promoting gastric emptying
• Weak 5-HT3 antagonism at higher doses

• Gastroparesis
• Migraine-associated nausea
• General nausea/vomiting when obstruction is excluded

• Acute dystonia
• Akathisia
• Parkinsonism
• Tardive dyskinesia with prolonged use
• Hyperprolactinemia
• Diarrhea

• Mechanical bowel obstruction
• GI perforation or bleeding
• Parkinson disease
• Previous dystonic reaction

Prochlorperazine

• D2 antagonist
• Useful for severe nausea, vestibular symptoms, migraine-related vomiting

Domperidone

• Peripheral D2 antagonist and prokinetic
• Fewer central extrapyramidal effects than metoclopramide
• Risk of QT prolongation and arrhythmias
• Availability varies by country.

C. H1 antihistamines

Drugs

• Cyclizine
• Dimenhydrinate
• Meclizine
• Promethazine
• Diphenhydramine

Best uses

• Motion sickness
• Vestibular disease
• Vertigo

Adverse effects

• Sedation
• Dry mouth
• Blurred vision
• Urinary retention
• Confusion, especially in older adults

D. Antimuscarinic

Scopolamine / hyoscine

• Particularly effective for motion sickness and vestibular nausea.
• Adverse effects: dry mouth, blurred vision, urinary retention, confusion.

E. NK1 antagonists

Drugs

• Aprepitant
• Fosaprepitant

Uses

• Highly emetogenic chemotherapy, usually in combination with a 5-HT3 antagonist and dexamethasone.

Important point

• Significant drug interactions through CYP pathways.

F. Corticosteroids

Dexamethasone

• Used mainly in chemotherapy-induced and postoperative vomiting.
• Also useful in raised intracranial pressure due to tumor-related cerebral edema when indicated.

G. Other agents

• Olanzapine: effective in chemotherapy-induced nausea and refractory nausea, but may cause sedation and metabolic adverse effects.
• Haloperidol: can be used in selected refractory cases, including palliative care; monitor QT interval and extrapyramidal effects.
• Lorazepam: useful for anticipatory chemotherapy-related nausea and anxiety-associated symptoms, but is not a routine first-line antiemetic.

9. Cause-specific management

A. Acute gastroenteritis

• Oral rehydration if possible
• IV fluids for severe dehydration
• Ondansetron may facilitate oral intake in selected patients
• Stool studies only when severe, bloody, prolonged, outbreak-related, immunocompromised, or recent antibiotic-associated illness
• Antibiotics only for selected proven/suspected bacterial causes

B. Intestinal obstruction

• NPO
• IV fluids and electrolyte correction
• NG decompression when indicated
• Early surgical review
• CT abdomen/pelvis to define site and cause
• Antibiotics if strangulation, perforation, or sepsis suspected

C. Acute pancreatitis

• IV fluids, analgesia, antiemetics
• Early enteral nutrition as tolerated
• Evaluate cause: gallstones, alcohol, hypertriglyceridemia, drugs, hypercalcemia
• Urgent ERCP if cholangitis or persistent biliary obstruction

D. Biliary colic/cholecystitis

• Analgesia, antiemetic, IV fluids
• Ultrasound
• Antibiotics and early cholecystectomy for acute cholecystitis where appropriate

E. DKA

• IV fluids
• IV insulin
• Potassium-guided replacement
• Identify and treat precipitant
• Antiemetic as supportive care only

F. Raised intracranial pressure or CNS emergency

• Urgent neuroimaging and specialist input
• Airway protection if reduced consciousness
• Treat the underlying cause
• Avoid assuming “gastritis” in a patient with severe headache, neurologic deficit, or altered sensorium

G. Migraine

• Antiemetic plus migraine-directed therapy such as NSAID, triptan when appropriate, or other acute migraine therapy
• Metoclopramide or prochlorperazine is commonly useful

H. Motion sickness/vestibular vomiting

• H1 antihistamine or scopolamine
• Treat underlying vestibular disorder
• Short-term vestibular suppressants only when appropriate

I. Gastroparesis

• Small, low-fat, low-fiber meals
• Optimize glycemic control in diabetes
• Metoclopramide for short-term use where appropriate
• Exclude mechanical obstruction
• Specialist review for refractory disease

J. Hyperemesis gravidarum

• Assess dehydration, ketonuria, weight loss, electrolyte disturbance, and alternate diagnoses.
• IV fluids and electrolyte correction
• Thiamine before dextrose if prolonged vomiting/malnutrition
• Pregnancy-compatible antiemetic regimen according to local obstetric guidance
• Consider admission if unable to tolerate oral intake, has dehydration, electrolyte imbalance, or significant weight loss

K. Cannabinoid hyperemesis syndrome

• Long-term frequent cannabis exposure
• Recurrent stereotyped vomiting episodes
• Temporary relief with hot showers/baths
• Normality between episodes

• Cannabis cessation is definitive treatment
• IV fluids and electrolyte correction
• Antiemetics may be variably effective
• Consider topical capsaicin or dopamine antagonist therapy under local protocol

L. Cyclic vomiting syndrome

• Stereotyped recurrent discrete attacks separated by symptom-free intervals
• Exclude metabolic, neurologic, obstructive, and toxic causes
• Acute therapy: hydration, antiemetics, migraine-directed treatment where indicated
• Prophylaxis and specialist management for recurrent disease

10. Important differential points for exams

11. Long-answer structure for “Approach to a patient with vomiting”

1. Define vomiting and differentiate it from regurgitation.
2. Assess severity using ABCDE.
3. Identify red flags: obstruction, acute abdomen, CNS disorder, GI bleed, sepsis, poisoning, pregnancy.
4. Take focused history: onset, content, pain, bowel symptoms, neurologic symptoms, drugs/toxins, pregnancy.
5. Examine hydration, abdomen, neurologic system, and signs of systemic disease.
6. Order directed investigations: CBC, electrolytes, renal function, glucose, pregnancy test, liver tests, lipase, ECG, imaging as indicated.
7. Give supportive care: NPO if indicated, IV fluids, potassium replacement, thiamine in prolonged vomiting, aspiration precautions.
8. Provide appropriate antiemetic.
9. Treat the underlying cause and involve surgery, gastroenterology, obstetrics, toxicology, or neurology where appropriate.
10. Monitor urine output, vitals, electrolytes, acid-base status, and nutritional state.

12. Viva questions and short answers