OPD Management of Vomiting - Complete Guide

1. Initial Assessment (History & Examination)

• Onset, duration, frequency, severity
• Character: projectile, bilious, blood-tinged (hematemesis)?
• Associated symptoms: fever, diarrhea, abdominal pain, headache, vertigo, jaundice
• Timing: morning (pregnancy, raised ICP, alcoholism), post-meal (gastroparesis, pyloric obstruction)
• Medications (opioids, NSAIDs, digoxin, chemotherapy, antibiotics)
• Recent travel, dietary history
• Last menstrual period (rule out pregnancy in women of childbearing age)
• Signs of dehydration: dry mucosa, reduced skin turgor, tachycardia, decreased urine output

• Projectile vomiting (raised ICP)
• Hematemesis
• Severe dehydration (unable to keep fluids down)
• Signs of peritonitis
• Altered consciousness or neurological signs
• Suspected bowel obstruction

2. Common OPD Causes

3. Investigations (if needed)

• CBC, RBS, LFT, RFT, serum electrolytes (Na+, K+)
• Urine pregnancy test (women of childbearing age)
• Urinalysis (ketonuria suggests starvation/DKA)
• Urine routine + culture (if UTI suspected)
• USG abdomen (if hepatobiliary/obstruction suspected)

4. General Non-Pharmacological Management

• Rest and oral rehydration - small, frequent sips of fluids (ORS/coconut water/clear fluids)
• Dietary advice: bland, low-fat diet; avoid spicy/fatty foods; small frequent meals rather than large meals
• Avoid triggers (odors, motion, large meals, alcohol)
• Ginger - evidence supports ginger for morning sickness and motion sickness (effective vs. placebo for seasickness, morning sickness, and chemotherapy-induced N&V)
• Elevate head of bed if gastroesophageal reflux suspected
• Adequate hydration monitoring (ketonuria = starvation signal)

5. Pharmacological Management - Antiemetic Drug Classes

6. Sample OPD Prescriptions by Etiology

A. Acute Gastroenteritis / Food Poisoning (Most Common OPD Cause)

1. Tab. Metoclopramide 10 mg - 1 tab TDS x 3-5 days
   (Before meals; avoid in children <1 yr; max 5 days due to extrapyramidal risk)

2. ORS sachet - 1 sachet in 200 mL water after every loose stool/vomiting episode

3. Tab. Ondansetron 4 mg - 1 tab TDS x 3-5 days
   (If metoclopramide not tolerated or vomiting severe; also available as 4 mg ODT)

4. Tab. Pantoprazole 40 mg - 1 tab OD before breakfast x 5-7 days
   (If associated dyspepsia/heartburn)

B. Pregnancy-Related Nausea & Vomiting (1st Trimester)

1. Cap./Tab. Doxylamine 10 mg + Pyridoxine (Vit B6) 10 mg
   - 2 tabs at bedtime; can add 1 tab in morning and 1 at mid-afternoon
   (First-line; Category A in pregnancy)

2. Tab. Ondansetron 4 mg - 1 tab TDS x 5 days
   (2nd line; avoid in 1st trimester if possible, but used when benefits outweigh risk)

3. Tab. Metoclopramide 10 mg - 1 tab TDS
   (Safe in pregnancy as adjunct)

4. Tab. Pyridoxine (Vit B6) 25 mg - 1 tab TDS

5. Ginger capsules 250 mg QID (non-pharmacologic option)

C. Motion Sickness

1. Tab. Cinnarizine 25 mg - 1 tab 30 min before travel, then 1 tab every 8 hours
   (H1 + calcium channel blocker; preferred for vertigo/motion sickness)

OR

2. Tab. Dimenhydrinate (Dramamine) 50 mg - 1 tab 30-60 min before travel; repeat every 4-6 hours
   (H1 antihistamine + anticholinergic; causes sedation)

OR

3. Scopolamine transdermal patch 1.5 mg - Apply behind ear 4 hours before travel
   (Best for prolonged motion sickness; anticholinergic effects common orally)

4. Tab. Meclizine 25 mg - 1 tab OD
   (Less sedating H1 antagonist; vertigo due to labyrinth dysfunction)

D. Drug-Induced Vomiting (Opioid, Antibiotics, NSAIDs)

1. Tab. Ondansetron 4 mg - 1 tab TDS (with each dose of offending drug)

2. Tab. Domperidone 10 mg - 1 tab TDS before meals
   (Peripheral dopamine D2 antagonist; less CNS/extrapyramidal effects than metoclopramide;
    Does NOT cross BBB well; preferred over metoclopramide for GI-origin emesis)

3. Consider dose reduction or substitution of the causative drug

E. Vomiting with Dyspepsia / Gastroparesis / Functional

1. Tab. Domperidone 10 mg - 1 tab TDS 15-30 min before meals x 2-4 weeks
   (Prokinetic; increases lower esophageal sphincter tone and gastric emptying)

2. Tab. Metoclopramide 10 mg - 1 tab TDS x 5 days
   (Short-term only due to tardive dyskinesia risk with prolonged use)

3. Tab. Pantoprazole/Omeprazole 40/20 mg - 1 tab OD before breakfast x 4 weeks
   (If associated GERD/dyspepsia)

4. Tab. Itopride 150 mg TDS (newer prokinetic with dual mechanism)

F. Vertigo-Associated Vomiting (Labyrinthitis / BPPV)

1. Tab. Betahistine 8-16 mg - 1 tab TDS x 2-4 weeks
   (Histamine agonist at H1; reduces endolymph pressure; useful in Meniere's)

2. Tab. Cinnarizine 25 mg - 1 tab TDS x 1-2 weeks
   (Vestibular sedative; H1 + calcium blocker)

3. Tab. Prochlorperazine 5 mg - 1 tab TDS (or 3-12.5 mg buccal for acute attacks)
   (Phenothiazine; dopamine antagonist; good for vestibular vomiting)

4. Epley's maneuver (for BPPV - refer physiotherapy)

G. Post-operative / Chemotherapy-Induced (for information)

• CINV acute: Ondansetron 8 mg IV/oral + Dexamethasone 8-12 mg + Aprepitant 125 mg (NK1 antagonist) 1 hr before chemo
• Delayed CINV: Aprepitant 80 mg OD x 2 days + Dexamethasone
• PONV prophylaxis: Ondansetron 4 mg IV + Dexamethasone 4-8 mg IV at end of procedure

7. Antiemetic Drug Summary Table

8. Important Cautions

• Metoclopramide: Do NOT use >5 days (risk of tardive dyskinesia, extrapyramidal effects). Contraindicated in GI obstruction, perforation, phaeochromocytoma.
• Domperidone: Risk of QTc prolongation at high doses. Use lowest effective dose.
• Ondansetron: Avoid in congenital long QT syndrome. Headache, constipation are common side effects. Dose reduction required in hepatic impairment.
• Phenothiazines (promethazine, prochlorperazine): Extrapyramidal side effects, hypotension, sedation. Avoid in Parkinson's disease.
• Antihistamines (dimenhydrinate, meclizine): Sedation, dry mouth, urinary retention, cycloplegia - use cautiously in elderly, BPH, glaucoma.
• Aprepitant (NK1): CYP3A4 interactions - can affect warfarin (decreases INR), dexamethasone dosing needs reduction.

9. When to Refer/Admit

• Unable to maintain oral hydration
• Signs of severe dehydration (>10% weight loss, ketonuria)
• Hematemesis or "coffee ground" vomiting
• Vomiting >3 weeks (chronic - needs workup for malignancy, gastroparesis)
• Projectile vomiting + headache/papilledema (raised ICP - neurosurgical emergency)
• Suspected bowel obstruction
• Hyperemesis gravidarum with weight loss and electrolyte imbalance

• Katzung's Basic and Clinical Pharmacology, 16th Edition - Antiemetic Agents chapter (pp. 1716-1719)
• Tintinalli's Emergency Medicine - Nausea and Vomiting management
• Lippincott Illustrated Reviews: Pharmacology - Antiemetic drugs