What are the causes and management of nausea and vomiting?

Causes and Management of Nausea and Vomiting

Nausea and vomiting are common symptoms with diverse etiologies that require targeted management based on the underlying cause, with treatment approaches focusing on both symptom relief and addressing the primary condition to improve patient morbidity, mortality, and quality of life.

Common Causes of Nausea and Vomiting

Gastrointestinal Causes

• Infections: Gastroenteritis, foodborne illness
• Obstruction: Malignant bowel obstruction, gastric outlet obstruction
• Motility disorders: Gastroparesis, dysmotility (particularly in diabetes)
• Functional disorders: Functional dyspepsia (present in 25-40% of patients) 1
• Constipation: Particularly with opioid use 1

Medication-Related Causes

• Chemotherapy: 70-80% of cancer patients on chemotherapy experience nausea/vomiting 1
• Opioids: Common side effect requiring prophylactic management 1
• Other medications: Antibiotics, antifungals, radiosensitizers 1

Metabolic/Endocrine Causes

• Electrolyte disturbances: Particularly hypercalcemia
• Metabolic disorders: Uremia, diabetic ketoacidosis
• Pregnancy: Common cause of acute nausea

Neurological Causes

• Central nervous system disorders: Brain metastases, increased intracranial pressure
• Vestibular disturbances: Labyrinthitis, Ménière's disease
• Migraines: Often associated with nausea/vomiting

Other Causes

• Radiation therapy: Common side effect in cancer treatment
• Psychological factors: Anxiety, anticipatory nausea (10-44% of chemotherapy patients) 1
• Post-surgical: Common postoperative complication

Evaluation Approach

Initial Assessment

• Determine duration: Acute (<7 days) vs. chronic (>4 weeks)
• Identify timing pattern: Continuous, intermittent, cyclic, postprandial
• Document associated symptoms: Pain, weight loss, early satiety
• Review medication list: Recent changes, known emetogenic drugs
• Assess for alarm symptoms: Hematemesis, weight loss, severe pain

Diagnostic Testing

• Basic laboratory tests: Complete blood count, comprehensive metabolic panel, pregnancy test
• Imaging studies:
  • Abdominal imaging for suspected obstruction
  • Brain imaging for suspected CNS pathology
• Gastric emptying studies: For suspected gastroparesis 1
• Endoscopy: For patients with alarm symptoms or risk factors for gastric malignancy

Management Strategies

Non-Pharmacological Approaches

• Dietary modifications:
  • Small, frequent meals
  • Avoiding trigger foods
  • Adequate hydration
• Probiotics: Consider during antibiotic therapy to reduce gastrointestinal side effects 2

Pharmacological Management

For Chemotherapy-Induced Nausea and Vomiting

• Highly emetogenic chemotherapy: Combination therapy with:
  • 5-HT3 receptor antagonists (ondansetron, granisetron)
  • Corticosteroids
  • NK-1 receptor antagonists (aprepitant) 1
• Moderately emetogenic chemotherapy:
  • 5-HT3 antagonist plus corticosteroid 1
  • Ondansetron 8mg 30 minutes before chemotherapy, with subsequent dose 8 hours later 3

For Medication-Induced Nausea

• First-line: Ondansetron 4-8mg orally every 8 hours as needed 2
• Alternative options:
  • Metoclopramide 5-10mg three times daily (particularly with delayed gastric emptying) 2
  • Prochlorperazine or haloperidol for persistent symptoms 1, 2

For Opioid-Induced Nausea

• Prophylactic treatment with antiemetics is highly recommended for patients with prior history 1
• Effective agents:
  • Phenothiazines (prochlorperazine, thiethylperazine)
  • Dopamine antagonists (metoclopramide, haloperidol)
  • For persistent nausea: Consider adding serotonin antagonists or alternative agents (scopolamine, dronabinol, olanzapine) 1

For Gastroparesis

• Prokinetic agents: Metoclopramide, erythromycin
• Antiemetics: 5-HT3 antagonists, phenothiazines 1

Special Considerations

Malignant Bowel Obstruction

• Olanzapine may be especially helpful 1
• Consider surgical intervention when appropriate

Refractory Nausea and Vomiting

• Consider combination therapy targeting different mechanisms
• Evaluate for alternative causes if symptoms persist
• Consider opioid rotation if opioid-induced 1

Clinical Pitfalls and Caveats

• Don't miss mechanical obstruction: Antiemetics will not resolve underlying obstruction and may mask important symptoms
• Avoid metoclopramide in patients with Parkinson's disease or history of tardive dyskinesia
• Monitor for QT prolongation with ondansetron, particularly in patients with electrolyte abnormalities or cardiac conditions 3
• Beware of serotonin syndrome when combining 5-HT3 antagonists with other serotonergic drugs 3
• Consider drug interactions: Aprepitant can interact with warfarin and other CYP3A4 substrates
• Don't ignore persistent symptoms: May indicate serious underlying pathology requiring further evaluation

By systematically evaluating the cause of nausea and vomiting and implementing targeted therapy, clinicians can effectively manage these symptoms and improve patient outcomes.