What is the appropriate urgent work‑up and initial management for a patient with a two‑week history of a persistent soapy odor causing nausea and vomiting?

Urgent Work-Up and Management for Persistent Soapy Odor with Nausea and Vomiting

This patient requires immediate laboratory evaluation to exclude metabolic emergencies and structural pathology, followed by empiric antiemetic therapy while awaiting results. The "soapy smell" perception is a concerning olfactory hallucination or distortion that may indicate neurologic, metabolic, or psychiatric pathology requiring urgent assessment 1, 2.

Immediate Laboratory Testing

Obtain the following labs urgently to exclude life-threatening metabolic causes:

• Complete metabolic panel to assess for hypercalcemia, electrolyte abnormalities (particularly hypokalemia and hypochloremia from vomiting), renal dysfunction, and metabolic alkalosis 1, 3
• Complete blood count to evaluate for infection or anemia 3
• Liver function tests and lipase to exclude hepatobiliary disease and pancreatitis 1, 3
• Thyroid-stimulating hormone to rule out hypothyroidism 1
• Urinalysis and urine pregnancy test (if applicable) 3
• Urine drug screen specifically to assess for cannabis use, as Cannabis Hyperemesis Syndrome (CHS) should be strongly suspected given the age group and symptom duration 1

Critical History Elements

Obtain specific details about:

• Cannabis use history (frequency, amount, duration) as CHS is increasingly common and presents with cyclic vomiting 1
• Timing and pattern of vomiting episodes—stereotypical episodes separated by symptom-free periods suggest Cyclic Vomiting Syndrome (CVS) 4
• Prodromal symptoms including sense of doom, panic, mental fog, diaphoresis, or early morning onset that characterize CVS 4
• Associated symptoms including abdominal pain (present in most CVS cases), headache, autonomic symptoms, or neurologic changes 4, 2
• Medication and toxin exposure as iatrogenic causes are common and reversible 5, 2

Imaging Considerations

• One-time esophagogastroduodenoscopy (EGD) or upper GI imaging is recommended to exclude obstructive lesions, but avoid repeated endoscopy 1
• CT head should be performed urgently if the olfactory hallucination is accompanied by headache, altered mental status, or focal neurologic signs, as this may indicate increased intracranial pressure 5, 6

Immediate Pharmacologic Management

While awaiting diagnostic results, initiate empiric antiemetic therapy:

• Start with dopamine receptor antagonists such as metoclopramide 10 mg IV/PO every 6 hours or prochlorperazine 10 mg IV/PO every 6-8 hours, titrated to maximum benefit and tolerance 1, 3
• Add ondansetron 8-16 mg IV if symptoms persist after initial dopamine antagonist administration, as it acts on different receptors providing complementary coverage 1
• Administer antiemetics on a scheduled basis rather than PRN, as prevention is far easier than treating established vomiting 1
• Consider haloperidol 1 mg IV/PO every 4 hours as an alternative dopamine antagonist with a different receptor profile 1

Hydration and Supportive Care

• Isotonic intravenous fluids (lactated Ringer's or normal saline) should be administered for severe dehydration, inability to tolerate oral intake, or ketonemia 1
• Correct electrolyte abnormalities particularly hypokalemia and hypomagnesemia, which are crucial in prolonged vomiting 1
• Thiamin supplementation should be given to prevent Wernicke's encephalopathy in patients with persistent vomiting 1

Cannabis Hyperemesis Syndrome Specific Considerations

If heavy cannabis use is confirmed:

• Do not stigmatize the patient and offer abortive and prophylactic therapy even with ongoing use, as treatments can still be effective 1
• Definitive diagnosis requires 6 months of cannabis cessation or at least 3 typical cycle lengths without vomiting 1
• Hot showers may provide temporary relief (characteristic of CHS) 1

Cyclic Vomiting Syndrome Specific Considerations

If stereotypical episodic pattern is identified:

• Early recognition and treatment during the prodromal phase (median 1 hour before vomiting onset) is ideal for abortive therapies 4
• Patient education on recognizing prodromal symptoms (sense of doom, panic, specific constitutional symptoms) is imperative for optimal care 4
• Abdominal pain presence should not preclude CVS diagnosis as it is present in most patients during episodes 4

Critical Pitfalls to Avoid

• Never use antiemetics in suspected mechanical bowel obstruction, as this can mask progressive ileus and gastric distension 1
• Do not assume CVS without excluding structural causes first, particularly given the unusual olfactory symptom 3
• Monitor for extrapyramidal symptoms with dopamine antagonists, particularly in young patients, and treat with diphenhydramine 50 mg IV if they develop 1
• Monitor for QTc prolongation when using ondansetron, especially in combination with other QT-prolonging agents 1
• Patients who cannot tolerate oral intake should not be discharged without imaging and should be considered for admission for IV hydration and expedited workup 3

Refractory Symptoms

If initial therapy fails after 4 weeks:

• Add dronabinol 2.5-7.5 mg PO every 4 hours as needed, which is FDA-approved for refractory nausea unresponsive to conventional antiemetics 1
• Consider adding proton pump inhibitor or H2 blocker if dyspepsia is present, as patients may confuse heartburn with nausea 1
• Reassess for underlying structural causes if symptoms persist beyond 1 week despite antiemetic therapy 3