Nausea

Nausea is an unpleasant, uneasy sensation in the stomach often described as the urge to vomit. It is a symptom rather than a disease and may be acute or chronic. Causes range from minor digestive disturbances to serious systemic illnesses. The mechanism of nausea involves stimulation of the vomiting center in the medulla oblongata by signals from the gastrointestinal tract, vestibular system, chemoreceptor trigger zone (CTZ), or higher brain centers (e.g., in response to emotions or sights).

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Causes

• Gastrointestinal disorders: gastroenteritis, peptic ulcers, gastroesophageal reflux disease (GERD), obstruction

• Infections: viral, bacterial, or parasitic infections

• Central nervous system (CNS) disorders: migraine, head injury, intracranial hypertension, brain tumors, meningitis

• Metabolic and endocrine disorders: diabetic ketoacidosis, uremia, Addison’s disease, hyperthyroidism, pregnancy (morning sickness)

• Vestibular disorders: motion sickness, labyrinthitis, Ménière’s disease

• Medications and toxins: chemotherapy, opioids, antibiotics, digoxin, alcohol, food poisoning

• Psychological causes: anxiety, stress, eating disorders

• Post-operative nausea and vomiting (PONV): common after anesthesia

• Cardiac and systemic causes: myocardial infarction, hypotension, severe pain

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Symptoms Associated

• Vomiting (may or may not occur)

• Pallor, sweating, salivation

• Dizziness, headache, abdominal cramps

• Loss of appetite

• In severe cases: dehydration, electrolyte imbalance

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Diagnosis

• History and physical exam: onset, duration, triggers, relation to meals or medications

• Laboratory tests: electrolytes, renal and liver function, blood glucose, thyroid profile

• Imaging: abdominal ultrasound, CT, MRI if CNS pathology suspected

• Special tests: ECG (if cardiac cause suspected), endoscopy (if persistent GI cause suspected)

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Treatment

1. General Measures

   • Rest in a quiet, well-ventilated room

   • Eat small, bland meals (e.g., crackers, rice, bananas)

   • Avoid fatty, spicy, or strong-smelling foods

   • Maintain hydration with clear fluids and oral rehydration solutions

2. Pharmacological Treatment

   • Antiemetics (choice depends on cause):

     • Ondansetron (5-HT3 receptor antagonist): 4–8 mg orally or IV every 8–12 hours, especially effective in chemotherapy, PONV

     • Metoclopramide (prokinetic/dopamine antagonist): 10 mg orally/IV up to 3 times daily, for gastroparesis or migraine-associated nausea

     • Domperidone: 10 mg orally three times daily (not available in all countries; less CNS penetration)

     • Prochlorperazine (dopamine antagonist): 5–10 mg orally or IV every 6–8 hours, effective in migraine and vestibular nausea

     • Promethazine (antihistamine/anticholinergic): 12.5–25 mg orally or IM, for motion sickness or vestibular causes

     • Meclizine: 25–50 mg orally 1 hour before travel, for motion sickness

     • Dexamethasone: often used in combination for chemotherapy-induced nausea

   • Ginger supplements: 250–500 mg orally up to 4 times daily, evidence supports mild efficacy

3. Condition-Specific Approaches

   • Pregnancy-related nausea (morning sickness): first-line is dietary modification and ginger; pharmacologic options include pyridoxine (vitamin B6) 10–25 mg orally every 8 hours, with or without doxylamine

   • Migraine-associated nausea: triptans (e.g., sumatriptan) may relieve both headache and nausea

   • Chemotherapy-induced nausea: combination therapy with ondansetron, dexamethasone, and aprepitant (NK1 receptor antagonist)

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Precautions

• Persistent or severe nausea requires urgent evaluation (risk of dehydration, underlying cardiac, metabolic, or neurological cause)

• Avoid overuse of antiemetics (risk of sedation, extrapyramidal symptoms, QT prolongation with ondansetron)

• Special caution in children and elderly due to increased risk of side effects

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Drug Interactions

• Ondansetron: risk of QT prolongation with SSRIs, macrolide antibiotics, and antipsychotics

• Metoclopramide: interacts with antipsychotics (extrapyramidal side effects), digoxin (reduced absorption), and levodopa (antagonistic effect)

• Promethazine/Meclizine: additive sedation with alcohol, benzodiazepines, opioids

• Domperidone: QT prolongation risk increased with azole antifungals, macrolides, and fluoroquinolones