Vomiting

Throwing Up/Vomiting

Vomiting is the forcible voluntary or involuntary emptying (“throwing up”) of stomach contents through the mouth.

Causes

• Reaction to certain smells or odors
• Food poisoning
• Indigestion
• Motion sickness
• Pregnancy-related morning sickness
• Crohn’s disease
• Heart attack
• Concussion or brain injury
• Brain tumor
• Ulcers
• Some forms of cancer
• Bulimia or other psychological illnesses
• Gastroparesis (slow stomach emptying, seen in people with diabetes)
• Ingestion of toxins or excessive alcohol

Pathophysiology

Four general pathways are activated by specific triggers, leading to nausea and vomiting:

1. Central Nervous System (CNS): Stimuli affect areas of the CNS, including the cerebral cortex and the limbic system. These areas are activated by elevated intracranial pressure, irritation of the meninges (blood or infection), and extreme emotional triggers (anxiety).
2. Chemoreceptor Trigger Zone (CTZ): Located in the area postrema in the floor of the fourth ventricle within the brain. This area is outside the blood-brain barrier and is exposed to substances circulating through the blood and cerebrospinal fluid. Common triggers include metabolic abnormalities, toxins, and medications. Activation is mediated by dopamine (D2) receptors, serotonin (5HT3) receptors, and neurokinin receptors (NK1).
3. Vestibular System: Activated by disturbances to the vestibular apparatus in the inner ear. These include movements that cause motion sickness and dizziness. This pathway is triggered via histamine (H1) receptors and acetylcholine (ACh) receptors.
4. Gastrointestinal Tract: Irritation or inflammation in the GI tract can activate sensory nerves that transmit signals to the vomiting center in the brain.

Vomiting Emergencies

Vomiting is common, but sometimes requires emergency medical attention. See a doctor immediately if you:

• Vomit for more than one day
• Suspect food poisoning
• Have a severe headache with a stiff neck
• Have severe abdominal pain

Seek emergency services if there’s blood in the vomit (hematemesis). Hematemesis symptoms include:

• Vomiting large amounts of red blood
• Spitting up dark blood
• Coughing up a substance that looks like coffee grounds

Vomiting blood is often caused by:

• Ulcers
• Ruptured blood vessels
• Stomach bleeding
• Some forms of cancer

This condition is often accompanied by dizziness. If you vomit blood, call your doctor immediately or go to the nearest emergency department.

Complications

Dehydration is the most common complication. Vomiting expels food and fluids, leading to dehydration, which can cause:

• Dry mouth
• Fatigue
• Dark urine
• Decreased urination
• Headache
• Confusion

Treatment

Treatment addresses the underlying cause. General supportive care includes:

• Hydration (oral rehydration solutions or IV fluids if severe)
• Dietary changes (bland diet, clear liquids initially)
• Anti-emetic drugs (to reduce nausea and vomiting)