What are the causes of chronic nausea?

Causes of Chronic Nausea

Chronic nausea is most commonly caused by cyclic vomiting syndrome (CVS), cannabinoid hyperemesis syndrome (CHS), medication side effects (particularly opioids), gastroparesis, functional disorders, and psychiatric conditions. 1, 2

Gastrointestinal Causes

Cyclic Vomiting Syndrome (CVS)

• Characterized by stereotypical episodes of acute-onset vomiting lasting <7 days with at least 3 discrete episodes in a year 1
• Episodes are separated by at least 1 week of baseline health, though milder symptoms like nausea may persist between episodes 1
• Often associated with mood disorders (anxiety, depression, panic disorder) in 50-60% of patients 1
• Migraine headaches are present in 20-30% of patients and serve as a supportive criterion for diagnosis 1
• Autonomic imbalances including postural orthostatic tachycardia syndrome are observed in a substantial subgroup 1

Cannabinoid Hyperemesis Syndrome (CHS)

• Characterized by cyclic vomiting, nausea, and abdominal pain in chronic cannabis users 1
• Diagnostic criteria include stereotypical episodic vomiting (≥3 times annually), cannabis use >1 year before symptom onset, frequency >4 times per week, and symptom resolution after cannabis cessation 1
• Hot water bathing behavior is reported in 71% of cases but is not pathognomonic as it also occurs in 48% of non-cannabis using CVS patients 1

Gastroparesis

• Delayed gastric emptying leading to chronic nausea, early satiety, and postprandial fullness 3
• Common causes include diabetes, post-surgical complications, and idiopathic factors 3

Functional Disorders

• Functional dyspepsia and chronic nausea vomiting syndrome can cause persistent nausea without identifiable structural abnormalities 3
• Often associated with visceral hypersensitivity and altered gut-brain interaction 4

Non-Gastrointestinal Causes

Medication-Induced Nausea

• Opioids are common culprits, causing nausea in a significant percentage of patients 1
• Other medications including antibiotics, NSAIDs, and certain antidepressants can cause chronic nausea 5
• For opioid-induced nausea, dopamine receptor antagonists like metoclopramide or haloperidol are effective 1, 5

Metabolic and Endocrine Disorders

• Hypercalcemia, uremia, adrenal insufficiency, and thyroid disorders can present with chronic nausea 5, 2
• Pregnancy should always be considered in women of childbearing age 6

Neurologic Disorders

• Migraine headaches, vestibular disorders, increased intracranial pressure, and seizure disorders can cause chronic nausea 1, 2
• Central nervous system pathology should be considered, especially with accompanying neurological symptoms 5

Psychiatric Conditions

• Anxiety, depression, and somatization disorders are associated with chronic nausea 4, 7
• Psychological factors can lower the threshold for nausea perception 7

Evaluation Approach

• Assess for alarm symptoms that suggest serious pathology (weight loss, hematemesis, severe abdominal pain) 2, 6
• Evaluate medication use, particularly opioids, which commonly cause nausea 1
• Consider cannabis use patterns, as CHS is increasingly recognized as a cause of chronic nausea 1
• For suspected CVS, identify triggers such as stress (70-80% of cases), sleep deprivation, hormonal fluctuations, travel, and infections 1
• Distinguish between mild CVS (<4 episodes/year lasting <2 days) and moderate-severe CVS (≥4 episodes/year lasting >2 days requiring ED visits) 1

Treatment Considerations

• For medication-induced nausea, consider dose reduction, opioid rotation, or adding antiemetics 1, 5
• For CVS, treatment depends on severity and phase of illness (prophylactic vs. abortive) 1
• For CHS, cannabis cessation is the definitive treatment 1
• For refractory cases, neuromodulators such as tricyclic antidepressants, gabapentin, and olanzapine have shown benefit 4
• Antiemetics should target the suspected neurotransmitter pathways involved (dopamine, serotonin, histamine) 5, 2

Common Pitfalls

• Failing to recognize CHS in cannabis users, attributing symptoms solely to CVS 1
• Misinterpreting hot water bathing behavior as pathognomonic for CHS when it also occurs in CVS 1
• Overlooking medication side effects, particularly from opioids 1
• Focusing only on vomiting while ignoring nausea and retching, which can be equally disabling 1
• Dismissing self-induced vomiting in CVS patients as malingering when it may be a self-soothing behavior 1