What are the possible causes of sudden vomiting in a patient of any age, with or without a significant medical history?

Causes of Sudden Vomiting

Sudden vomiting in any patient requires immediate assessment for life-threatening causes, with acute gastroenteritis being the most common benign etiology, but bilious vomiting, altered mental status, severe abdominal pain, or hematemesis demand urgent evaluation for surgical emergencies, metabolic crises, or neurologic catastrophes.

Immediate Life-Threatening Causes to Rule Out

In Infants and Young Children

• Intestinal obstruction (malrotation with volvulus, intussusception) presents with bilious vomiting and represents a surgical emergency requiring immediate imaging 1, 2
• Pyloric stenosis causes projectile non-bilious vomiting, typically between 2-8 weeks of age, with a palpable "olive" mass in the right upper quadrant 1
• Intussusception manifests with crampy intermittent pain (inconsolable crying), vomiting progressing to bilious emesis, and "currant jelly" stools 2
• Increased intracranial pressure from hydrocephalus, shaken baby syndrome, or mass lesions causes projectile vomiting with altered mental status 3
• Metabolic emergencies including inborn errors of metabolism, congenital adrenal hypoplasia, and symptomatic hypoglycemia 3
• Sepsis, meningitis, or encephalitis present with vomiting plus fever, lethargy, or toxic appearance 3

In Older Children and Adults

• Appendicitis causes vomiting with progressive right lower quadrant pain and peritoneal signs 3
• Diabetic ketoacidosis presents with vomiting, altered mental status, and characteristic fruity breath 3
• Acute coronary syndrome can manifest as nausea and vomiting, particularly in women and diabetics 4
• Increased intracranial pressure from mass lesions, hemorrhage, or meningitis 3, 4
• Toxic ingestions including medications, drugs, or poisons 3, 4
• Acute kidney injury or uremia 3, 4
• Bowel obstruction from adhesions, hernias, or malignancy 4

Common Benign Causes

Gastrointestinal Infections

• Acute gastroenteritis is the leading cause of acute vomiting in all age groups, typically viral in origin 3, 5, 4
• Food poisoning from bacterial toxins or contaminated food 5, 4

Medication and Toxin Effects

• Medication adverse effects should always be suspected and reviewed in any patient with new-onset vomiting 5, 4, 6
• Chemotherapy-induced emesis occurs within minutes to hours (acute) or after 24 hours (delayed) of administration 7
• Polypharmacy is particularly problematic in elderly patients 8

Other Common Causes

• Pregnancy must be considered in all women of reproductive age 5, 4
• Acute migraine headaches often present with sudden nausea and vomiting 4
• Vestibular disturbances including labyrinthitis or benign positional vertigo 4
• Gastroesophageal reflux disease (GERD) can cause recurrent vomiting episodes 1, 9

Critical Red Flags Requiring Urgent Evaluation

Any of these findings mandate immediate comprehensive assessment:

• Bilious (green) vomiting indicates obstruction distal to the ampulla of Vater and is a surgical emergency until proven otherwise 1, 2, 9, 3
• Bloody vomiting (hematemesis) or blood in stool suggests mucosal injury, ulceration, or intussusception 1, 2, 3
• Projectile vomiting raises concern for pyloric stenosis in infants or increased intracranial pressure at any age 1, 9, 3
• Altered mental status or lethargy suggests metabolic disorder, intracranial pathology, or severe dehydration 9, 3
• Severe abdominal distension indicates possible intestinal obstruction 9, 3
• Toxic, septic, or apprehensive appearance 3
• Inconsolable crying or excessive irritability in infants 3
• Severe dehydration (≥10% deficit) 3
• Bent-over posture suggesting peritonitis 3

Age-Specific Considerations

Patient Demographics Affecting Risk

• Younger patients (<50 years) and women are more prone to nausea and vomiting from various causes 7
• Young women with breast cancer receiving chemotherapy experience particularly severe nausea 7
• Elderly patients have multiple potential causes including polypharmacy, though physiological aging alone does not cause vomiting 8

Diagnostic Approach

Initial Assessment Priority

• Assess airway, breathing, and circulation first 3
• Evaluate hydration status using capillary refill, mucous membranes, and urine output 1, 3
• Determine if vomiting is bilious or non-bilious, as this fundamentally changes urgency and approach 1, 2

History Elements to Elicit

• Timing and duration: acute (<7 days) versus chronic (≥4 weeks) 4, 6
• Character: projectile, bilious, bloody, or non-bilious 1, 2, 9, 3
• Associated symptoms: fever, abdominal pain, diarrhea, headache, altered mental status 3, 4, 6
• Medication and substance use including recent changes 5, 4, 6
• Relationship to food ingestion 4, 6
• Recent exposures: sick contacts, travel, new foods 3, 5
• Weight changes: loss or poor gain indicates serious pathology 1, 9

Physical Examination Focus

• Abdominal examination for distension, masses (pyloric "olive"), peritoneal signs 1, 3
• Hydration assessment: skin turgor, mucous membranes, capillary refill 1, 3
• Neurologic examination for altered mental status, meningismus, focal deficits 3
• Vital signs including orthostatic changes 3

Imaging and Laboratory Studies

• Plain abdominal radiograph is the first imaging study for suspected obstruction, showing dilated loops and air-fluid levels 2
• Ultrasound is the modality of choice for suspected pyloric stenosis in infants 1
• Upper GI series evaluates for malrotation when bilious vomiting is present in infants 2
• Laboratory testing (electrolytes, blood gases, renal and liver function) is required for any patient with dehydration or red flag signs 3

Common Pitfalls to Avoid

• Do not dismiss bilious vomiting in any age group—it requires immediate surgical consultation even if the patient appears well 1, 2
• Do not confuse regurgitation with true vomiting, particularly in infants where benign reflux is common 1
• Do not assume viral gastroenteritis without excluding red flag signs, as serious conditions can initially appear benign 3
• Do not forget pregnancy testing in all women of reproductive age 5, 4
• Do not overlook medication review, as adverse effects are extremely common and often reversible 5, 4, 8
• Malrotation with volvulus can present at any age, not just in newborns, so maintain vigilance for changing vomiting patterns 1