What are the possible causes of nausea?

Possible Causes of Nausea

Nausea has numerous potential causes that must be systematically assessed, including gastrointestinal disorders, medications (especially opioids), metabolic abnormalities, CNS pathology, chemotherapy/radiation therapy, constipation, hypercalcemia, gastric outlet or bowel obstruction, and pregnancy-related factors. 1

Medication and Toxin-Related Causes

• Opioid-induced nausea occurs in up to 50% of patients when opioids are initiated or doses are significantly increased 1
• Other medications that commonly cause nausea include digoxin, phenytoin, carbamazepine, and tricyclic antidepressants—blood levels should be checked when these are suspected 1
• Chemotherapy and radiation therapy are major causes of nausea with significant quality of life impact 1

Gastrointestinal Causes

• Constipation is a frequently overlooked but common cause of nausea, particularly in patients on opioids 1
• Gastric outlet obstruction and bowel obstruction (mechanical or functional) must be ruled out 1
• Gastritis and gastroesophageal reflux disease can be managed with proton pump inhibitors or H2 receptor antagonists 1
• Gastroparesis and other disorders of gastric emptying represent important chronic causes 2, 3

Metabolic and Endocrine Causes

• Hypercalcemia is a critical metabolic cause that must be assessed 1
• Pregnancy should always be considered in women of childbearing age—nausea and vomiting of pregnancy typically begins at 4-6 weeks gestation and peaks at 8-12 weeks 1
• Other metabolic abnormalities including electrolyte disturbances and organ system failure 1, 2

Neurologic Causes

• CNS pathology including increased intracranial pressure, tumors, or other structural lesions 1
• Vestibular disturbances and motion sickness 2, 4
• Migraine headaches are commonly associated with nausea 2, 5
• Cyclic vomiting syndrome, which shares pathophysiology with migraines and is triggered by stress, sleep deprivation, hormonal fluctuations, and infections 1

Infectious Causes

• Acute gastroenteritis and other viral syndromes are common causes of acute nausea 2, 5
• Foodborne illness 2

Psychiatric and Functional Causes

• Anxiety and panic disorders can manifest with nausea—benzodiazepines may be helpful for anxiety-related nausea 1
• Chronic nausea vomiting syndrome represents a functional disorder 4, 3

Critical Pitfalls to Avoid

• Never assume opioid-induced nausea without ruling out constipation first, as constipation is both common and easily treatable 1
• In cancer patients, always assess for hypercalcemia, which is frequently missed 1
• Do not overlook mechanical bowel obstruction, particularly in patients with abdominal malignancies or prior surgeries 1
• Hot water bathing behavior is not pathognomonic for cannabinoid hyperemesis syndrome—approximately 48% of CVS patients without cannabis use also exhibit this behavior 1