What are the differential diagnoses for nausea?

Differential Diagnoses for Nausea

Nausea arises from gastrointestinal, neurologic, metabolic, medication-related, and psychiatric causes, with the specific etiology determined by timing, associated symptoms, and patient risk factors. 1

Gastrointestinal Causes

Mechanical Obstruction

• Bowel obstruction is life-threatening and diagnosed by abdominal distention, absent bowel sounds, and colicky pain 1
• Upper endoscopy is essential to exclude mechanical gastric outlet obstruction before diagnosing functional or motility disorders 1, 2
• Malignancy must be excluded by upper endoscopy, particularly in patients ≥55 years with alarm features 1

Motility Disorders

• Gastroparesis affects 20-40% of diabetic patients and 25-40% of functional dyspepsia patients, presenting with nausea, vomiting, early satiety, postprandial fullness, and bloating 1
• Diagnosis requires gastric emptying scintigraphy performed for at least 4 hours (retention >10% at 4 hours confirms gastroparesis), as shorter durations miss approximately 25% of cases 1, 2
• Functional dyspepsia is defined by Rome IV criteria as bothersome epigastric pain, burning, postprandial fullness, or early satiation without structural disease on endoscopy 1
• Gastroparesis and functional dyspepsia are indistinguishable based on symptoms alone and may represent the same spectrum of gastric neuromuscular dysfunction 1

Inflammatory and Infectious Conditions

• Peptic ulcer disease explains approximately 10% of upper-GI symptom presentations and requires upper endoscopy for definitive diagnosis 1
• Gastroenteritis and other viral syndromes are typical causes of acute nausea lasting up to 7 days 3

Episodic Vomiting Syndromes

• Cyclic vomiting syndrome (CVS) has a prevalence of approximately 2% in US adults, characterized by stereotypical episodes of acute-onset vomiting lasting <7 days, with at least 3 discrete episodes per year separated by at least 1 week of baseline health 4, 1
• CVS episodes are often triggered by stress (70-80% of patients), sleep deprivation, hormonal fluctuations, or physiological stressors 4
• Most CVS patients (approximately 65%) experience prodromal symptoms lasting a median of 1 hour before vomiting onset, including fatigue, mental fog, anxiety, and autonomic symptoms 4
• Cannabinoid hyperemesis syndrome (CHS) is paradoxical cannabis-associated vomiting, with patients reporting need for hot water bathing to alleviate symptoms 1
• Cannabis use has a pooled prevalence of 47% in CVS patients, and distinguishing CHS from CVS requires detailed cannabis use history 1

Neurologic Causes

• Central nervous system tumors cause nausea through increased intracranial pressure, typically accompanied by other neurologic signs 1
• Increased intracranial pressure from any cause warrants urgent evaluation 1
• Acute migraine headaches are a common cause of acute nausea and vomiting 3
• Vestibular disturbances frequently present with nausea 3

Metabolic and Endocrine Causes

• Pregnancy is the most common endocrinologic cause and must be considered in any woman of childbearing age 5
• Diabetic complications, particularly hyperglycemia, cause gastric dysmotility and can slow gastric emptying during diagnostic testing 1, 2
• Thiamin deficiency should be evaluated in patients with persistent vomiting >2-3 weeks to prevent neurological complications 1
• Hypercalcemia must be ruled out as a treatable cause of nausea 4
• Hypokalemia, hypothyroidism, and diabetes mellitus are other metabolic causes requiring exclusion 4

Medication and Toxin-Related Causes

• Opioid-induced nausea occurs in 10-50% of patients receiving opioids and worsens gastric emptying 4, 1
• Chemotherapy-induced nausea and vomiting has major impact on quality of life and should be managed per antiemesis guidelines 4
• Radiation therapy commonly causes nausea and vomiting 4
• NSAIDs, anticholinergics, and other medications can precipitate or worsen dyspeptic symptoms 1
• Cannabinoid withdrawal syndrome (CWS) occurs commonly on cessation of heavy and prolonged cannabis use 1

Psychiatric and Psychogenic Causes

• Psychogenic disorders should be considered when organic causes are excluded 1
• Anxiety-related nausea can be managed with benzodiazepines 4
• Psychiatric comorbidity is associated with CVS, along with younger age and tobacco use 1

Critical Diagnostic Pitfalls to Avoid

• Do not diagnose functional dyspepsia without endoscopy in adults ≥55 years or those with alarm features (weight loss, dysphagia, hematemesis, upper abdominal mass), as structural disease must be excluded first 1
• Do not attribute persistent or severe vomiting to functional dyspepsia, as Rome IV criteria consider vomiting a red flag warranting further investigation 4, 1
• Symptoms correlate poorly with degree of gastric emptying delay, so relying solely on symptoms for diagnosis is inadequate 1, 2
• Shorter gastric emptying test durations (<4 hours) are inaccurate and miss approximately 25% of gastroparesis cases 1, 2
• Failure to control blood glucose during gastric emptying testing can lead to false positive results in diabetic patients 1, 2
• Missing cannabis use history is critical for distinguishing CHS from CVS, as cannabis use augments hot water bathing behavior 1
• Not accounting for medications affecting gastric emptying (prokinetics, opioids, anticholinergics) can lead to inaccurate diagnostic results 1, 2