What are the causes of vomiting?

Causes of Vomiting

Vomiting results from activation of the emetic reflex by numerous endogenous and exogenous triggers, with causes broadly categorized as gastrointestinal, infectious, metabolic, neurologic, psychiatric, medication-related, and surgical emergencies 1, 2.

Acute Vomiting (< 7 days)

The most common causes of acute vomiting are viral gastroenteritis and foodborne illness, particularly in children under 2 years of age 3, 4, 2.

Common Acute Causes:

• Gastroenteritis/viral syndromes - watery diarrhea with vomiting, most frequent in children under 2 years 3, 4
• Foodborne illness - acute onset related to recent food ingestion 2, 5
• Acute migraine headaches - episodic pattern with associated headache 2
• Vestibular disturbances - associated with vertigo and motion sickness 1, 2
• Early pregnancy - typically first trimester 2, 5
• Medication adverse effects - always suspect as a cause 4, 2

Life-Threatening Acute Causes Requiring Immediate Evaluation:

Bilious vomiting at any age is a surgical emergency until proven otherwise, with midgut volvulus being the critical consideration 3, 6.

In Infants:

• Midgut volvulus - accounts for 20% of bilious vomiting cases in first 72 hours 3
• Duodenal atresia - most common proximal obstruction, "double bubble" sign on X-ray 3
• Jejunoileal atresia - "triple bubble" sign with absent distal gas 3
• Hypertrophic pyloric stenosis - forceful, projectile nonbilious vomiting at 3-6 weeks (or 2-8 weeks) of age 3, 7
• Intussusception - bilious vomiting with "currant jelly" stools and crampy pain 3, 6
• Necrotizing enterocolitis - in premature/ill neonates 4
• Shaken baby syndrome - altered mental status, trauma history 4
• Hydrocephalus - increased intracranial pressure signs 4
• Inborn errors of metabolism - metabolic decompensation 4
• Congenital adrenal hypoplasia - salt-wasting crisis 4
• Sepsis/meningitis/encephalitis - fever, altered mental status 4

In Older Children:

• Appendicitis - right lower quadrant pain, fever 4
• Intracranial mass lesion - headache, neurologic signs 4
• Diabetic ketoacidosis - hyperglycemia, acidosis 4
• Reye's syndrome - post-viral, altered mental status 4
• Toxic ingestions - history of exposure 4
• Uremia - renal failure 4

Chronic Vomiting (≥ 4 weeks)

Chronic vomiting has a broad differential diagnosis spanning multiple organ systems 2, 5.

Gastrointestinal Causes:

• Gastroesophageal reflux disease (GERD) - most common cause of nonbilious vomiting/regurgitation in infants, typically resolves with age when associated with normal weight gain 3, 7
• Gastroparesis - impaired gastric motility 1
• Peptic ulcer disease - epigastric pain 5
• Chronic intestinal obstruction - partial obstruction patterns 5

Functional/Episodic Disorders:

Cyclic vomiting syndrome (CVS) is characterized by stereotypical episodes of acute-onset vomiting lasting <7 days, with at least 3 discrete episodes per year (2 in prior 6 months), separated by at least 1 week of baseline health 8.

• CVS triggers - stress (70-80% of patients), sleep deprivation, hormonal fluctuations, travel, motion sickness, acute infections, surgery, prolonged fasting, or intense exercise 8
• CVS comorbidities - mood disorders (anxiety, depression, panic disorder in 50-60%), migraine (20-30%), seizure disorders (3%), postural orthostatic tachycardia syndrome 8
• Cannabinoid hyperemesis syndrome - chronic cannabis use with compulsive hot water bathing (though hot bathing occurs in 48% of CVS patients without cannabis use) 8
• Abdominal migraine - episodic abdominal pain with vomiting 9
• Functional vomiting - chronic unexplained vomiting 1
• Chronic idiopathic nausea - persistent nausea without clear cause 1

Metabolic Causes:

• Diabetic ketoacidosis - hyperglycemia with ketosis 4
• Uremia - chronic kidney disease 4, 2
• Hypercalcemia - elevated calcium levels 2
• Adrenal insufficiency - cortisol deficiency 2
• Inborn errors of metabolism - various enzymatic defects 4

Neurologic Causes:

• Increased intracranial pressure - mass lesions, hydrocephalus 4, 2
• Migraine headaches - episodic with headache 2
• Vestibular disorders - vertigo, balance disturbances 1, 2

Infectious Causes:

• Chronic infections - hepatitis, HIV, parasitic infections 2
• Meningitis/encephalitis - CNS infections 4

Psychiatric Causes:

• Anxiety disorders - associated with CVS and other functional disorders 8, 2
• Depression - comorbid with chronic vomiting 8, 2
• Eating disorders - bulimia nervosa, anorexia nervosa 2

Medication and Toxin-Related:

• Medication side effects - chemotherapy, opioids, antibiotics, NSAIDs 4, 2
• Alcohol toxicity - acute or chronic use 2
• Cannabis hyperemesis - chronic heavy cannabis use 8

Critical Red Flags Requiring Urgent Evaluation

Never dismiss bilious vomiting as "just gastroenteritis" - it indicates obstruction distal to the ampulla of Vater and requires immediate imaging and surgical consultation 3, 6.

• Bilious (green) vomiting - surgical emergency at any age 3, 6, 4
• Bloody vomitus or "currant jelly" stools - suggests mucosal damage from intussusception or other serious pathology 3, 6
• Severe dehydration - prolonged skin tenting, cool extremities, decreased capillary refill, rapid deep breathing 3
• Altered mental status - suggests CNS pathology or severe metabolic derangement 4
• Toxic/septic appearance - requires immediate evaluation for sepsis 4
• Inconsolable cry or excessive irritability - may indicate surgical abdomen or increased intracranial pressure 4
• Abdominal distension - suggests obstruction 7, 4
• Weight loss or poor weight gain - indicates significant pathology 7, 4
• Projectile vomiting in infants - red flag requiring thorough evaluation for pyloric stenosis or other obstruction 7