Definition and epidemiology
Vomiting (emesis) is the forceful, coordinated expulsion of gastric and sometimes intestinal contents through the mouth. It is distinct from regurgitation, which is passive and effortless, and from rumination, which involves voluntary re-chewing of food.
Vomiting is one of the most common presenting complaints across all clinical settings, from pediatric emergency departments to oncology clinics. It is a symptom, not a disease, and the ICD-10 code R11 is used when vomiting is the primary complaint and a specific underlying diagnosis has not yet been established.
- Affects nearly all age groups; etiology differs markedly by age
- In infants, regurgitation and gastroesophageal reflux are common and usually benign
- In adults, acute gastroenteritis and medication side effects are leading causes
- Chemotherapy-induced nausea and vomiting affects a majority of patients on emetogenic regimens without prophylaxis
- Nausea and vomiting of pregnancy affects a large proportion of pregnancies, typically in the first trimester
- Bilious vomiting in a neonate is a surgical emergency until malrotation with volvulus is excluded
- Pyloric stenosis causes non-bilious projectile vomiting in infants 2-8 weeks old with a palpable olive mass
- Vomiting classically causes hypokalemic, hypochloremic metabolic alkalosis
- Morning vomiting with headache suggests raised intracranial pressure
- Vomiting that relieves abdominal pain suggests bowel obstruction
- Mallory-Weiss tear causes hematemesis after forceful retching; Boerhaave syndrome is esophageal rupture
- Ondansetron (5-HT3 antagonist) is first-line for chemotherapy-induced and gastroenteritis-related vomiting
- Doxylamine-pyridoxine is first-line pharmacologic therapy for nausea and vomiting of pregnancy
Etiology and risk factors
Causes are best organized by mechanism and age group.
Gastrointestinal causes
- Acute gastroenteritis (viral, bacterial, parasitic)
- Mechanical obstruction (pyloric stenosis, intussusception, malrotation/volvulus, adhesions, hernia, malignancy)
- Biliary or pancreatic disease (cholecystitis, pancreatitis)
- Appendicitis
- Peptic ulcer disease and gastroparesis
Central nervous system causes
- Increased intracranial pressure (tumor, hemorrhage, hydrocephalus)
- Migraine
- Vestibular disorders (labyrinthitis, Meniere disease, benign paroxysmal positional vertigo)
Metabolic and endocrine causes
- Diabetic ketoacidosis
- Uremia
- Adrenal insufficiency
- Pregnancy (hyperemesis gravidarum)
Drug- and toxin-related causes
- Chemotherapy and radiation therapy
- Opioids, antibiotics, and many other medications
- Alcohol intoxication and withdrawal
- Digoxin toxicity
Psychogenic and functional causes
- Cyclic vomiting syndrome
- Cannabinoid hyperemesis syndrome (chronic heavy cannabis use)
- Bulimia nervosa
Risk factors include recent travel or sick contacts, new medications, pregnancy, prior abdominal surgery (adhesions), chronic heavy cannabis or alcohol use, and underlying malignancy.
Pathophysiology
Vomiting is coordinated by the vomiting center in the medulla, which integrates input from several pathways:
- Chemoreceptor trigger zone (CTZ) in the area postrema, outside the blood-brain barrier, detects circulating toxins, drugs, and metabolic byproducts (dopamine D2 and serotonin 5-HT3 receptors are key)
- Vagal and splanchnic afferents from the GI tract relay mechanical distension, mucosal irritation, and inflammatory signals
- Vestibular system contributes via histamine (H1) and muscarinic (M1) receptors, explaining motion sickness
- Higher cortical centers mediate psychogenic vomiting and anticipatory nausea
Once triggered, the reflex produces retrograde giant contractions of the small intestine, relaxation of the lower esophageal sphincter and pylorus, and coordinated contraction of the diaphragm and abdominal muscles to expel gastric contents.
Prolonged vomiting causes loss of hydrochloric acid and potassium, producing a hypochloremic, hypokalemic metabolic alkalosis, a classic finding tested with pyloric stenosis and severe hyperemesis.
Clinical features
History should characterize the vomiting itself and associated symptoms.
Pattern of vomitus
| Feature | Suggests |
|---|---|
| Bilious (green/yellow) | Obstruction distal to the ampulla of Vater |
| Non-bilious, projectile | Pyloric stenosis (infants) |
| Feculent | Distal small bowel or colonic obstruction |
| Blood (hematemesis) | Upper GI bleed (ulcer, varices, Mallory-Weiss tear) |
| Undigested food, hours after eating | Gastroparesis or gastric outlet obstruction |
Associated symptoms
- Abdominal pain, distension, or guarding suggests a surgical abdomen
- Headache, visual changes, or morning vomiting suggests raised intracranial pressure
- Vertigo and tinnitus suggest a vestibular cause
- Fever and diarrhea suggest infectious gastroenteritis
- Vomiting relieving abdominal pain is classic for bowel obstruction
Red flag features requiring urgent evaluation
- Bilious or feculent vomiting
- Hematemesis
- Signs of dehydration or hemodynamic instability
- Severe abdominal pain, rigidity, or peritonism
- New headache, altered mental status, or focal neurologic deficits
- Vomiting in a neonate (especially bilious) or with failure to thrive
Diagnosis
Diagnosis is directed by history and exam; vomiting itself requires minimal workup unless red flags or dehydration are present.
Initial assessment
- Vital signs and assessment of volume status
- Abdominal exam for distension, tenderness, bowel sounds, or masses
- Neurologic exam if CNS cause suspected
- Pregnancy test in any woman of reproductive age
Laboratory studies
- Basic metabolic panel to assess electrolytes (classic finding: hypokalemic, hypochloremic metabolic alkalosis), renal function, and glucose
- Liver enzymes, lipase/amylase if biliary or pancreatic cause suspected
- Urinalysis and urine ketones
Imaging
- Abdominal X-ray or ultrasound if obstruction suspected
- Ultrasound is first-line for suspected pyloric stenosis (hypertrophied pylorus) and for suspected gallbladder disease
- Upper GI contrast study or CT if malrotation/volvulus or complex obstruction suspected
- CT or MRI brain if a central cause is suspected
Special tests
- Upper endoscopy if structural or mucosal disease suspected
- Gastric emptying scintigraphy if gastroparesis suspected after excluding mechanical obstruction
Differential diagnosis
Vomiting is nonspecific; the differential depends heavily on age and associated features.
- Gastroenteritis — most common cause overall; associated diarrhea, fever, sick contacts
- Bowel obstruction — distension, absent or high-pitched bowel sounds, prior surgery
- Pyloric stenosis — projectile non-bilious vomiting in infants 2-8 weeks old, palpable olive-shaped mass
- Appendicitis — periumbilical pain migrating to RLQ, anorexia, fever
- Increased intracranial pressure — morning vomiting, headache, papilledema
- Hyperemesis gravidarum — pregnancy, ketonuria, significant weight loss
- Diabetic ketoacidosis — polyuria, polydipsia, Kussmaul breathing, fruity breath odor
- Cyclic vomiting syndrome / cannabinoid hyperemesis — recurrent discrete episodes, relief with hot showers in cannabinoid hyperemesis
Management
Management targets the underlying cause plus symptomatic and supportive care.
General principles
- Identify and treat the underlying etiology; vomiting is a symptom, not a diagnosis
- Correct dehydration and electrolyte abnormalities with oral or intravenous rehydration
- Address any surgical emergency (obstruction, volvulus, appendicitis) promptly with surgical consultation
Antiemetic drug classes (choice depends on etiology)
- 5-HT3 receptor antagonists (e.g., ondansetron) — first-line for chemotherapy-induced and postoperative nausea/vomiting, and widely used in gastroenteritis
- Dopamine antagonists (e.g., metoclopramide, prochlorperazine) — useful for gastroparesis and general nausea; metoclopramide also promotes gastric motility
- Antihistamines/anticholinergics (e.g., diphenhydramine, meclizine, scopolamine) — preferred for motion sickness and vestibular causes
- NK1 receptor antagonists (e.g., aprepitant) — added for highly emetogenic chemotherapy regimens
- Corticosteroids (e.g., dexamethasone) — adjunct in chemotherapy-induced nausea and vomiting
- Doxylamine-pyridoxine combination — first-line pharmacologic option for nausea and vomiting of pregnancy per American College of Obstetricians and Gynecologists guidance
Guideline consensus (ASCO, MASCC/ESMO for chemotherapy-induced nausea and vomiting; ACOG for pregnancy) generally agrees on stepwise escalation starting with lower-risk agents and adding classes based on severity and risk category, though specific regimen choices vary slightly between societies.
Non-pharmacologic measures
- Small, frequent, low-fat meals; avoiding triggers
- Ginger has modest evidence for nausea of pregnancy and chemotherapy
- Acupressure (P6 point) has some supportive evidence
When surgery is indicated
- Mechanical bowel obstruction with ischemia or failure of conservative management
- Pyloric stenosis (pyloromyotomy)
- Malrotation with volvulus (emergency surgery)
Complications and prognosis
Most vomiting is self-limited and resolves with treatment of the underlying cause. Complications arise mainly from prolonged or severe vomiting.
- Dehydration and electrolyte derangement — hypokalemia, hypochloremia, metabolic alkalosis
- Aspiration pneumonia — particularly in patients with reduced consciousness or impaired airway reflexes
- Mallory-Weiss tear — mucosal laceration at the gastroesophageal junction from forceful retching, causing hematemesis
- Boerhaave syndrome — rare but life-threatening esophageal rupture from severe forceful vomiting, presenting with chest pain, subcutaneous emphysema, and mediastinitis
- Dental erosion and esophagitis — with chronic vomiting (e.g., bulimia nervosa)
- Malnutrition and weight loss — with hyperemesis gravidarum or cyclic vomiting syndrome
Prognosis depends entirely on the underlying cause: acute gastroenteritis typically resolves within days, while vomiting from malignancy, bowel obstruction, or increased intracranial pressure requires addressing the primary pathology for resolution.
VOMITING causes: Vestibular, Obstruction, Metabolic/Medications, Infection, Toxins/Tumor, Intracranial pressure, Nausea of pregnancy, Gastroenteritis/GI (ulcer, gallbladder)
Practice questions
1. A 3-week-old male infant presents with non-bilious, projectile vomiting after every feed for the past 5 days. He remains hungry after vomiting. On exam, a small olive-shaped mass is palpated in the epigastrium. Laboratory studies show a metabolic abnormality. Which acid-base and electrolyte pattern is most likely?
2. A 45-year-old woman with a history of multiple abdominal surgeries presents with 2 days of worsening bilious vomiting, diffuse abdominal distension, and absent bowel movements. Abdominal X-ray shows dilated small bowel loops with air-fluid levels and no colonic gas. What is the most likely diagnosis?
3. A 29-year-old woman presents with 3 weeks of severe nausea and vomiting, unable to tolerate oral intake, with a 6% weight loss from pre-pregnancy weight. Urinalysis shows ketonuria. Which is the most appropriate first-line pharmacologic therapy?
Frequently asked questions
What causes vomiting?
Vomiting is caused by activation of the brainstem vomiting center through gastrointestinal, central nervous system, metabolic, or drug-related triggers. Common causes include gastroenteritis, medication side effects, bowel obstruction, migraine, increased intracranial pressure, and pregnancy. The specific cause is identified through history, examination, and targeted testing based on associated symptoms.
What are the first symptoms that come before vomiting?
Nausea is almost always the first symptom, often accompanied by increased salivation, sweating, pallor, and a feeling of unease. Many people also notice retching, which is the forceful attempt to vomit without actually expelling contents, just before true vomiting occurs. These prodromal symptoms result from autonomic nervous system activation preceding the vomiting reflex.
How is the cause of vomiting diagnosed?
Diagnosis starts with a detailed history covering the pattern of vomiting, associated symptoms, and red flags, plus a physical exam focused on hydration status and the abdomen. Basic blood tests, a pregnancy test when relevant, and imaging such as abdominal ultrasound or CT are added if obstruction, infection, or a surgical cause is suspected. In infants or when a central cause is suspected, additional specific imaging is used.
Is vomiting dangerous or can it be cured?
Vomiting itself is usually self-limited and resolves once the underlying cause, such as a viral infection, is treated or resolves on its own. It becomes dangerous when prolonged, since it can cause dehydration, electrolyte imbalance, or in rare cases esophageal injury. Treating the specific underlying condition typically resolves the vomiting completely.
Vomiting vs regurgitation — what is the difference?
Vomiting is an active, forceful process driven by coordinated abdominal and diaphragmatic muscle contractions, usually preceded by nausea. Regurgitation is passive and effortless, with food or liquid simply flowing back up, often seen with reflux or an esophageal motility problem. This distinction helps narrow the differential, since regurgitation points toward esophageal rather than gastric or systemic causes.
Key drugs
Related conditions and differentials
Sources and further reading
StatPearls (NCBI Bookshelf)MedlinePlusWHO ICD-10: R11
Educational content for medical students, prepared by the WhiteCoat Pro editorial team with AI assistance; every page is reviewed by a second AI model for factual errors. It is not medical advice and does not replace the product label, local guidelines or a clinician.