Sudden Vomiting Without Nausea: Causes and Red Flags

Vomiting without preceding nausea ("projectile" or "unheralded") suggests distinct mechanisms:

Neurologic (Central)

• Increased intracranial pressure (mass, hemorrhage, hydrocephalus) — stimulates area postrema directly.
• Migraine (especially vestibular).
• Brainstem lesions.

Vestibular

• Acute vertigo (BPPV, vestibular neuritis, Ménière's) — vomiting via vestibulo-emetic pathway.
• Motion sickness.

Gastrointestinal

• Gastric outlet obstruction (pyloric stenosis, antral tumor) — projectile, non-bilious.
• Acute pancreatitis — severe epigastric pain radiating to back.
• Superior mesenteric artery syndrome.

Metabolic/Toxic

• Diabetic ketoacidosis (DKA), uremia, adrenal crisis.
• Medications: chemo, opioids, digoxin toxicity, antibiotics.
• Alcohol intoxication.

Other

• Pregnancy (hyperemesis gravidarum).
• Psychogenic (conversion, bulimia — though usually self-induced).
• Post-tussive (violent coughing).

Red Flags — Emergency Evaluation

• Headache + vomiting (worst headache of life, morning).
• Focal neurologic signs.
• Hematemesis, melena.
• Severe abdominal pain, rigidity.
• Dehydration, electrolyte imbalance.

Unheralded vomiting warrants prompt medical assessment to rule out neurologic or surgical emergencies.