What are the possible diagnoses and treatment options for an adult patient presenting with nausea and vomiting?

Differential Diagnosis for Adult Nausea and Vomiting

The differential diagnosis for adult nausea and vomiting must be approached systematically by first excluding life-threatening causes, then categorizing by acute versus chronic presentation, and finally determining whether the etiology is gastrointestinal, medication-related, metabolic, neurologic, or psychogenic. 1, 2

Immediate Life-Threatening Causes to Exclude First

Before considering benign etiologies, immediately evaluate for cardiac ischemia with an ECG, particularly in patients with concurrent left-sided pain (ear, jaw, neck, shoulder), as nausea and vomiting frequently accompany acute coronary syndrome, especially in women. 3

Additional emergent causes requiring urgent evaluation include: 3, 2

• Esophageal perforation (severe pain with dysphagia)
• Aortic dissection (severe chest/back pain)
• Bowel obstruction (abdominal distension, absent bowel sounds)
• Increased intracranial pressure (headache, altered mental status, focal neurologic deficits)

Acute Nausea and Vomiting (Duration <7 Days)

Acute symptoms lasting less than 7 days are typically self-limited and treated symptomatically without extensive evaluation in the absence of alarm features. 1, 2

Most Common Causes:

• Gastrointestinal infections and food poisoning (most common overall) 4
• Medication adverse effects (always suspect) 4, 1
• Early pregnancy (reproductive-age women) 4, 1
• Acute migraine headaches 1
• Vestibular disturbances 1
• Viral syndromes 1

Alarm Features Requiring Hospitalization: 4

• Severe dehydration
• Significant metabolic abnormalities
• Suspected surgical causes (peritoneal signs, obstruction)

Chronic Nausea and Vomiting (Duration ≥4 Weeks)

Chronic symptoms require comprehensive evaluation as they indicate diverse pathophysiology with gastrointestinal, metabolic, neurologic, psychiatric, or medication-related causes. 1, 5

Gastrointestinal Causes:

After excluding anatomic and biochemical causes, categorize by gastric emptying status: 5

Delayed Gastric Emptying:

• Gastroparesis (diabetic, post-viral, idiopathic) 5
• Gastric outlet obstruction (malignancy, peptic ulcer disease) 6

Normal Gastric Emptying:

• Cyclic vomiting syndrome (stereotypical episodes of acute-onset vomiting lasting <7 days, ≥3 episodes per year separated by ≥1 week of baseline health) 3, 5
• Functional dyspepsia 5
• Chronic intestinal pseudo-obstruction 5
• Rumination syndrome 5

Medication and Toxin-Related Causes:

Always review medication list as this is among the most common reversible causes: 1, 2

• Opioids
• Chemotherapy agents 6
• Antibiotics
• NSAIDs
• Selective serotonin reuptake inhibitors
• Digoxin
• Theophylline
• Alcohol and substance use

Metabolic and Endocrine Causes: 1, 2

• Diabetic ketoacidosis
• Uremia (chronic kidney disease)
• Hypercalcemia
• Adrenal insufficiency
• Thyroid disorders
• Pregnancy

Neurologic Causes: 1, 2

• Increased intracranial pressure (tumor, hemorrhage, hydrocephalus)
• Vestibular disorders (labyrinthitis, Ménière's disease)
• Migraine headaches
• Autonomic dysfunction

Psychiatric and Psychogenic Causes: 1, 2

• Anxiety disorders
• Depression
• Eating disorders (bulimia nervosa, anorexia nervosa)
• Cannabinoid hyperemesis syndrome

Critical Diagnostic Approach

For chronic symptoms, determine specific characteristics to narrow differential: 2

Timing Patterns:

• Morning predominance: pregnancy, increased intracranial pressure, uremia 2
• Postprandial: gastroparesis, gastric outlet obstruction, functional dyspepsia 2, 5
• Cyclical pattern: cyclic vomiting syndrome, cannabinoid hyperemesis 3, 5

Associated Symptoms:

• Early satiety with postprandial vomiting: gastric outlet obstruction (perform endoscopic or fluoroscopic evaluation) 6
• Headache with focal neurologic signs: intracranial pathology 2
• Vertigo: vestibular disorders 1
• Abdominal pain: consider gastrointestinal obstruction, pancreatitis, biliary disease 2

Treatment Approach Based on Etiology

For Non-Chemotherapy-Related Acute Symptoms:

First-line treatment uses dopamine receptor antagonists, which have the strongest evidence: 7, 8

• Metoclopramide 10-20 mg PO/IV 3-4 times daily 7
• Prochlorperazine 5-10 mg PO/IV 3-4 times daily 7
• Haloperidol 0.5-2 mg IV/PO every 6-8 hours 7

Second-line agents if first-line fails within 1-2 hours: 7, 3

• Add 5-HT3 receptor antagonist (ondansetron 4-8 mg IV/PO every 8 hours) 7
• Add dexamethasone 2-8 mg IV/PO 3

For Breakthrough Symptoms Despite Initial Treatment:

The principle is to ADD (not replace) medications with different receptor mechanisms: 7

• Combination of ondansetron + metoclopramide + dexamethasone addresses three different pathways 7
• Switch from PRN to scheduled around-the-clock dosing for at least 24-48 hours if symptoms persist 7
• Consider olanzapine 5-10 mg PO for refractory symptoms 7, 3

For Chemotherapy-Induced Nausea:

High emetogenic risk requires three-drug prophylaxis: 6

• NK1 receptor antagonist + 5-HT3 receptor antagonist + dexamethasone 6

For breakthrough despite optimal prophylaxis: 6

• Add olanzapine if not already receiving it prophylactically 6

Special Considerations for Gastric Outlet Obstruction:

In patients with known malignancy and symptoms of obstruction (early satiety, postprandial vomiting): 6

• Perform endoscopic or fluoroscopic evaluation 6
• Endoscopic stent placement is preferred for patients with shorter life expectancy 6
• Gastrojejunostomy is preferred for longer prognosis 6

Common Pitfalls to Avoid

Never assume benign etiology without ECG in patients with nausea, vomiting, and any left-sided pain (ear, jaw, neck, shoulder), as this represents potential atypical cardiac ischemia presentation. 3

Avoid using ondansetron as monotherapy for acute non-chemotherapy nausea—dopamine antagonists have stronger first-line evidence in this setting. 7, 8

Do not simply re-dose the same antiemetic—if breakthrough occurs, add agents with different mechanisms rather than increasing frequency of the same drug. 7

Recognize that ondansetron can cause constipation, which may paradoxically worsen nausea if not addressed. 7

Avoid first-generation antihistamines (diphenhydramine) as they can exacerbate hypotension, tachycardia, and sedation without superior antiemetic efficacy. 7

Before adding multiple antiemetics, exclude treatable causes: constipation, electrolyte abnormalities, increased intracranial pressure, bowel obstruction, and inadequate hydration. 7

Symptoms are poor predictors of functional versus pathological illness—chronic symptoms warrant investigation regardless of severity. 4