Vomiting

Disease Description (Causes and Pathophysiology · Main Symptoms)

• Definition: Vomiting is the expulsion of stomach contents through the esophagus and out of the mouth, often preceded by nausea.
• Main causes (various mechanisms):
  • Digestive system abnormalities: peptic ulcer disease, delayed gastric emptying (pyloric obstruction), gastrointestinal obstruction, gastritis, food poisoning, appendicitis, cholecystitis, pancreatitis, etc.
  • Nervous system: increased intracranial pressure (cerebral hemorrhage, brain tumor), meningitis, migraine, vestibular system abnormalities (motion sickness, Meniere’s disease)
  • Endocrine and metabolic: uremia, liver failure, electrolyte abnormalities, thyroid and adrenal diseases, ketoacidosis, etc.
  • Thoracic and cardiac diseases: acute myocardial infarction, severe lung disease
  • Pregnancy: morning sickness in early pregnancy (hyperemesis gravidarum in severe cases)
  • Drugs and toxins: anticancer drugs, opioids, digoxin, etc.
  • Infection: viral or bacterial gastrointestinal infection (generally accompanied by diarrhea)
  • Psychological factors: eating disorders (self-induced after binge eating), stress
• Pathophysiology summary: Vomiting occurs through the combined effects of stimulation of the vomiting center in the medulla (including the chemoreceptor trigger zone) and stimulation of the stomach, intestines, and vestibular organs. Repeated vomiting may cause dehydration, electrolyte abnormalities (hypochloremic metabolic alkalosis, hypokalemia), and nutritional deficiencies.
• Main symptoms: nausea, repeated vomiting, loss of appetite, increased salivation, abdominal pain, fever, dizziness, headache (when intracranial pressure is increased), tinnitus and vertigo (with vestibular system abnormalities). The smell and color of the vomit (seawater-like, foul-smelling, bloody, etc.) may provide clues to the cause.

Treatment Methods and Precautions

• General principles: Treat the underlying cause after diagnosis (e.g., surgical or nonsurgical decompression for intestinal obstruction, antibiotics for infection, etc.). Supportive treatment includes fluids, electrolyte correction, and antiemetics.
• Supportive treatment
  • Fluid and electrolyte correction (intravenous fluids, potassium and chloride supplementation, etc.)
  • Antiemetics (selected according to the cause and situation)
    • 5-HT3 antagonist: Ondansetron — effective for chemotherapy-induced, postoperative, and severe vomiting
    • Dopamine antagonists: Metoclopramide (improves vomiting and gastric emptying), Prochlorperazine
    • Antihistamine/anticholinergic agents: Dimenhydrinate, Meclizine, Scopolamine — useful for vestibular vomiting (motion sickness, Meniere’s disease)
    • NK1 antagonist: Aprepitant — used for severe chemotherapy-related vomiting
    • Steroid: Dexamethasone — an adjunct for chemotherapy-induced and postoperative vomiting
  • In cases of stomach or intestinal obstruction: fasting, nasogastric tube insertion (decompression), and surgical treatment if necessary
  • Pregnancy-related vomiting: Pyridoxine (vitamin B6) ± Doxylamine (first-line treatment for vomiting during pregnancy); in severe cases, consider intravenous fluids, hospitalization, and antiemetics
  • Nutritional management: intravenous nutrition if necessary (in cases of severe persistent vomiting or fasting)
• Lifestyle measures and self-care
  • Eat small amounts frequently (the BRAT diet: bananas, rice, apples, toast, etc.); avoid greasy and spicy foods and strong odors
  • Drink fluids frequently in small sips; electrolyte drinks may be helpful
  • Do not lie flat immediately after vomiting; turn the head to the side to protect the airway
  • Rinse the mouth and maintain oral hygiene after vomiting
• Precautions and contraindications
  • Patients with impaired consciousness or a risk of aspiration may need nasogastric tube insertion and airway protection
  • Repeated vomiting may cause dehydration, electrolyte abnormalities, and kidney failure — emergency treatment is necessary
  • For certain antiemetics, side effects (QT prolongation, sedation, etc.) must be considered in children, pregnant women, and patients with cardiovascular disease
• Complications: dehydration, electrolyte abnormalities (hypochloremic metabolic alkalosis, hypokalemia), aspiration pneumonia, Mallory–Weiss tear, Boerhaave syndrome (esophageal rupture), esophagitis, weight loss and malnutrition

Checklist Before an Outpatient Visit (Including Items to Prepare and Example Questions)

• Items to prepare and records
  • Record the time, frequency, and characteristics of vomiting during the past 24–72 hours (including the appearance, smell, and presence of blood in the vomit)
  • Record accompanying symptoms: abdominal pain, fever, diarrhea, vertigo, headache, chest pain, decreased urine output, etc.
  • List of medications currently being taken (including prescriptions, OTC medicines, herbal medicines, and supplements) and allergy history
  • Recent meals, possible food-poisoning exposure, travel history, and possibility of pregnancy (for women, the date of the last menstrual period)
  • Existing conditions (heart, liver, kidney, diabetes, brain diseases, etc.) and recent test results
• Information helpful to provide at the outpatient visit
  • When it began, how often it occurs, and in what situations it worsens (after meals, upon waking in the morning, etc.)
  • Changes in urination or consciousness caused by vomiting, changes in weight, and the location and severity of abdominal pain
• Situations in which an emergency visit is recommended (visit a hospital immediately)
  • Inability to drink fluids because of persistent, uncontrolled vomiting; bloody vomiting; chest pain, difficulty breathing, coma, severe abdominal pain, high fever, extremely low urine output, etc.

Examples of General Questions to Ask the Doctor

• "What is the most likely cause of these symptoms?"
• "What tests do you recommend (blood tests, imaging, endoscopy), and why?"
• "What are the expected effects and side effects of the prescribed medication?"
• "How should I check for and manage dehydration and electrolyte abnormalities caused by vomiting at home?"
• "When should I visit the emergency room?"

Examples of Disease-Specific Questions

• If stomach or intestinal obstruction is suspected: "When are abdominal imaging tests (abdominal CT or ultrasound) or nasogastric decompression needed to confirm intestinal obstruction?"
• In cases of pregnancy-related vomiting (women of childbearing age): "Is it necessary to check whether I am pregnant? Which medications can be used safely during pregnancy (such as vitamin B6 and doxylamine)?"