Nausea and Vomiting Triggered by Smells or Food: Causes and Management

Common Triggers

Sensory hypersensitivity: Hyperosmia (pregnancy, migraine, Lyme, autoimmune) → smell-triggered nausea.

Diagnostic Approach

1. History: timing, triggers, associated symptoms, medication review.
2. Exam: hydration, abdominal, neurologic.
3. Labs: BMP, LFTs, lipase, β-hCG, TSH, CBC.
4. Imaging: abdominal US/CT if obstruction/surgical cause suspected.
5. Endoscopy if upper GI alarm features.

Symptomatic Management

Category	Examples
Foodborne	Bacterial toxins (S. aureus, B. cereus), viruses (norovirus), parasites
GI disorders	GERD, gastroparesis, IBS, Crohn's, ulcer, obstruction
Medications	Opioids, antibiotics, chemo, NSAIDs, digoxin, metformin
Vestibular	Motion sickness, vestibular migraine, BPPV
Pregnancy	hCG, estrogen, progesterone; peaks 9–12 wks
Neurologic	Migraine, increased ICP, concussion
Psychogenic	Anxiety, phobias, eating disorders

Agent	Use Case
Ondansetron (5-HT3 antagonist)	Chemo, post-op, gastroenteritis; QT caution
Metoclopramide (D2 antagonist + prokinetic)	Gastroparesis, migraine; avoid long-term (TD risk)
Prochlorperazine / promethazine	Vertigo, migraine; sedation
Scopolamine patch	Motion sickness
Doxylamine + pyridoxine (Diclegis)	First-line pregnancy nausea
Ginger (250 mg q6h)	Mild nausea; pregnancy-safe
Benzodiazepines (lorazepam)	Anticipatory nausea (chemo)

Lifestyle

• Small, frequent, bland meals (BRAT: banana, rice, applesauce, toast).
• Cold/room-temp foods (less odor).
• Hydration: sip electrolyte solutions.
• Avoid triggers; fresh air; acupressure P6 (Neiguan).

Persistent unexplained nausea (>1 month) warrants specialist referral.