What is the appropriate treatment for a female patient with a one‑week history of a soapy‑smelling breath and nausea/vomiting, whose labs are normal except for mild thrombocytosis and elevated red cell distribution width?

Management of Soapy Smell with Nausea and Vomiting

This patient requires evaluation for neuropsychiatric causes of olfactory hallucinations (phantosmia) rather than infectious or metabolic disease, as all laboratory values are essentially normal and do not explain her symptoms.

Laboratory Interpretation

Your patient's labs reveal no significant pathology:

• Complete metabolic panel is entirely normal 1: Normal glucose, electrolytes, renal function (eGFR 72), and liver enzymes all argue against metabolic encephalopathy or hepatic/renal dysfunction
• Thyroid function is normal (TSH 0.762, T4 9.1), excluding thyroid-related causes 1
• CBC shows only minor abnormalities that are not clinically significant for acute illness:
  • Mild thrombocytosis (453) is nonspecific and can occur with inflammation, iron deficiency, or be reactive 2, 3
  • Slightly elevated RDW (15.6%) suggests mild anisocytosis but is not diagnostic of any acute process 4, 5
  • Low-normal MCH (26.0) may indicate early iron deficiency but does not cause neurological symptoms 5
• Lipase is normal (20 U/L), excluding pancreatitis 6

Differential Diagnosis for Phantosmia with Nausea

The complaint of a persistent "soapy smell" for one week represents an olfactory hallucination (phantosmia) rather than an actual environmental odor. Key considerations include:

Neurological Causes

• Seizure disorder (temporal lobe epilepsy can present with olfactory auras and nausea) 6
• Migraine with aura (olfactory hallucinations can precede or accompany migraines) 6
• Post-viral olfactory dysfunction (COVID-19 and other viral URIs can cause persistent phantosmia) 6

Psychiatric Causes

• Anxiety disorder (can manifest with somatic symptoms including olfactory distortions and nausea) 6
• Depression (associated with altered sensory perception) 6

Medication/Toxin-Related

• Review all medications and supplements for potential olfactory side effects 6
• Consider environmental or occupational exposures 6, 1

Recommended Management Algorithm

Immediate Actions

1. Obtain detailed history focusing on:

   • Timing and triggers of the olfactory hallucination 1
   • Associated neurological symptoms: headache, visual changes, weakness, confusion 6
   • Recent viral illness or COVID-19 infection 6
   • Psychiatric history and current stressors 6
   • Complete medication and supplement list 6
   • Occupational and environmental exposures 6, 1

2. Perform focused neurological examination looking for:

   • Cranial nerve deficits (especially olfactory testing) 6
   • Focal neurological signs 6
   • Mental status changes 6

Symptomatic Treatment for Nausea

Prescribe antiemetic therapy while pursuing diagnostic workup:

• First-line: Ondansetron 4-8 mg orally every 8 hours as needed 6
• Alternative: Metoclopramide 10 mg orally three times daily (avoid if seizure suspected) 6
• Consider: Meclizine 25 mg every 6-8 hours if vestibular component suspected 6

Diagnostic Workup Based on Clinical Findings

If headache, focal neurological signs, or seizure history present:

• Order MRI brain with and without contrast to evaluate for structural lesions, temporal lobe abnormalities, or demyelinating disease 6
• Consider EEG if seizure disorder suspected 6

If recent viral illness or COVID-19:

• Diagnose as post-viral olfactory dysfunction 6
• Reassure that phantosmia often resolves spontaneously over weeks to months 6
• Consider olfactory training (sniffing essential oils twice daily) 6

If psychiatric symptoms predominate:

• Screen for anxiety and depression using validated tools 6
• Consider psychiatric referral for cognitive behavioral therapy 6
• Trial of SSRI may help both psychiatric symptoms and phantosmia 6

Follow-up

• Reassess in 3-5 days to evaluate response to antiemetics and determine if further workup needed 6, 1
• If symptoms persist beyond 2 weeks or worsen, proceed with neuroimaging regardless of initial presentation 6

Important Caveats

• Do not attribute symptoms to the mild lab abnormalities (elevated RDW and platelets), as these are nonspecific and do not cause neurological symptoms 7, 4, 3
• Avoid unnecessary antibiotics, as there is no evidence of infection (normal WBC, no fever documented, normal inflammatory markers implied by clinical stability) 6, 8
• Red flags requiring urgent neuroimaging: new-onset severe headache, focal weakness, visual changes, altered consciousness, or seizure activity 6
• Consider carbon monoxide exposure if household members have similar symptoms or if patient uses gas appliances 6