Nausea & Vomiting — Causes, Treatment & Emergency Signs — Causes, Diagnosis & When to See a Doctor | MyMedicPlus

Nausea is the unpleasant, distressing sensation of imminent vomiting, often accompanied by salivation, pallor, sweating, and tachycardia. Vomiting (emesis) is the forceful expulsion of gastric contents coordinated by the medullary vomiting centre (area postrema) in the brainstem, which integrates signals from the gastrointestinal tract, vestibular system, cerebral cortex, and chemoreceptor trigger zone. They are symptoms, not diagnoses, arising from gastrointestinal, neurological, hormonal, toxic, or psychogenic stimuli. Nausea and vomiting are among the most common symptoms across all age groups, ranging from the self-limiting discomfort of viral gastroenteritis to life-threatening conditions such as bowel obstruction or Addisonian crisis. While often self-limiting, persistent vomiting poses significant risks: dehydration, electrolyte disturbance (hypokalaemia, metabolic alkalosis), aspiration, oesophageal Mallory-Weiss tears, and Wernicke encephalopathy from thiamine deficiency in prolonged cases. Distinguishing benign from serious causes requires systematic assessment of associated symptoms, timing, character, and patient context including medications and medical history.

Gastrointestinal causes include viral gastroenteritis (norovirus and rotavirus — the most frequent overall causes), food poisoning (Staphylococcus aureus, Bacillus cereus, Salmonella — onset within hours of contaminated food), gastroparesis (delayed gastric emptying — particularly in diabetics), and peptic ulcer disease or gastritis. Pregnancy causes morning sickness in 70-80% of cases (affecting any time of day); severe hyperemesis gravidarum affects 0.3-3% and requires hospitalisation. Motion sickness results from vestibular-visual mismatch. Medications frequently causing nausea include opioids, chemotherapy agents, antibiotics (metronidazole, erythromycin), NSAIDs, SSRIs, and digoxin toxicity. Inner ear disorders (labyrinthitis, benign paroxysmal positional vertigo — BPPV, Meniere's disease) cause vomiting with vertigo. Serious causes requiring urgent assessment include acute appendicitis (nausea with periumbilical pain migrating to right lower quadrant), bowel obstruction (bilious vomiting with colicky pain and distension), acute pancreatitis (vomiting with severe epigastric pain radiating to the back), meningitis (projectile vomiting with severe headache and neck stiffness), diabetic ketoacidosis, hepatic failure, and acute myocardial infarction — especially in women and diabetics, where vomiting may be the predominant presenting feature.

Seek emergency care immediately for vomiting of bright red blood or coffee-ground material (haematemesis) — this indicates upper gastrointestinal bleeding from peptic ulcer, oesophageal varices, or Mallory-Weiss tear, all requiring emergency endoscopy. Call emergency services for projectile vomiting with sudden severe headache described as the worst of one's life and neck stiffness — this may indicate subarachnoid haemorrhage or bacterial meningitis. Seek emergency assessment for vomiting accompanied by severe, constant abdominal pain or board-like abdominal rigidity (peritonitis or acute pancreatitis), vomiting with confusion or altered consciousness (possible meningitis, Wernicke encephalopathy, or metabolic emergency), inability to keep any fluids down for more than 12 hours in adults or 6 hours in young children (dehydration risk), vomiting in a known diabetic with blood glucose above 14 mmol/L (possible diabetic ketoacidosis), or vomiting with chest pain suggesting cardiac event. Signs of dehydration — persistent dizziness, very dark urine, dry mouth, sunken eyes, decreased skin turgor in children — warrant urgent medical attention.

Clinical history includes timing relative to meals, character (projectile vs. effortless regurgitation vs. forceful vomiting), colour and contents (bilious — green, suggests obstruction above or at duodenum; faeculent — brown, suggests distal bowel obstruction or gastrocolic fistula), frequency, duration, and associated symptoms including diarrhoea, fever, abdominal pain, headache, and vertigo. A pregnancy test in all women of reproductive age is essential before ordering further tests or prescribing medications. Blood tests assess electrolytes, kidney function (urea, creatinine), liver function tests, blood glucose and ketones, pancreatic enzymes (amylase and lipase — elevated in pancreatitis), full blood count, and lactate in cases of suspected sepsis. Abdominal X-ray identifies bowel obstruction (air-fluid levels, dilated loops). Abdominal ultrasound or CT identifies gallstones, appendicitis, pancreatitis, and other structural causes. Upper endoscopy (gastroscopy) evaluates haematemesis and suspected peptic ulcer. Neuroimaging (CT brain or MRI) is performed when neurological cause is suspected.

Oral rehydration therapy is the cornerstone of treatment for vomiting from gastroenteritis — administer small, very frequent sips of oral rehydration solution, approximately 5-10 mL (one teaspoon) every 1-2 minutes rather than larger volumes that trigger further vomiting. Cold or room-temperature fluids are generally better tolerated than warm. A bland diet (BRAT: banana, rice, applesauce, toast) and gradual reintroduction of food aids recovery without prolonging illness. Antiemetics provide effective relief: ondansetron (5-HT3 antagonist — preferred in adults and children over one month, well-tolerated), metoclopramide (dopamine antagonist — avoid in children due to dystonia risk), domperidone (preferred in Parkinson's disease), and prochlorperazine (useful for vertigo-related vomiting). For pregnancy-related nausea, pyridoxine (vitamin B6) alone or combined with doxylamine is first-line pharmacological therapy; ginger has modest evidence. Antihistamines (cyclizine, promethazine) are effective for motion sickness and pregnancy nausea. Hyperemesis gravidarum requires hospitalisation with intravenous fluids, antiemetics, and thiamine supplementation to prevent Wernicke encephalopathy. Severe vomiting causing dehydration requires intravenous fluid replacement with normal saline and potassium correction.

Prevent infectious gastroenteritis through thorough handwashing with soap and water for at least 20 seconds before food preparation, after using the toilet, and after contact with sick individuals. Cook poultry and meats to safe internal temperatures (75°C for chicken), refrigerate leftovers promptly (within two hours), and avoid cross-contamination between raw meat and ready-to-eat foods. For motion sickness, take antihistamines (cinnarizine, promethazine) or scopolamine patches 30-60 minutes before travel. During travel, sit in the front seat of cars, over the wing on aircraft, or midship on boats — positions with least motion. Fix gaze on a stationary point on the horizon and avoid reading during travel. For pregnancy nausea, eat small frequent dry snacks (crackers, dry toast) before rising from bed and avoid strong odours or spicy and fatty foods that trigger nausea. Ginger tea, ginger biscuits, or ginger capsules may provide modest relief. Avoid excessive alcohol, which directly causes gastritis and vomiting.

Seek emergency care immediately for vomiting of blood or coffee-ground material, projectile vomiting with severe headache and neck stiffness, vomiting with severe abdominal pain, or signs of severe dehydration including confusion, inability to stand, absent urination for eight or more hours, or sunken eyes and dry mouth in infants. Go to an emergency department for vomiting in a known diabetic with high blood glucose — possible ketoacidosis — or vomiting with chest pain in an adult over 40 years. Seek urgent medical assessment the same day for vomiting lasting more than 24 hours without improvement in adults, signs of dehydration (dark concentrated urine, dizziness on standing, dry mouth), vomiting in pregnancy causing inability to keep down any fluids or food (hyperemesis gravidarum), or vomiting following a head injury. Arrange a routine appointment within one to two days for persistent nausea without vomiting lasting more than a few days, recurring episodes without clear cause, or nausea starting with a new medication. Children under two years who vomit for more than 12 hours or show any dehydration signs need prompt same-day medical review.