What is the management for post-tussive vomiting?

Management of Post-Tussive Vomiting

The management of post-tussive vomiting should focus on antiemetic therapy with ondansetron as the first-line agent due to its superior efficacy in preventing vomiting with fewer side effects compared to other antiemetics. 1

Pharmacological Management

First-Line Therapy

• Ondansetron (5-HT3 receptor antagonist) is the preferred first-line agent:
  • Dosing: 8 mg (sublingual) every 4-6 hours during episodes of vomiting 2
  • Advantages: Higher success rate in preventing recurrent vomiting, fewer side effects, and better oral fluid intake tolerance 1
  • Considerations: Baseline ECG is advised as ondansetron is associated with prolonged QTc 2

Second-Line Options

• Promethazine (Dopamine receptor antagonist with antihistaminergic effects):

  • Dosing: 12.5-25 mg by mouth/per rectal every 4-6 hours during episodes 2
  • Side effects: CNS depression, anticholinergic effects, extrapyramidal symptoms 2
  • Caution: Peripheral IV administration can cause tissue injury, including gangrene or thrombophlebitis 2

• Prochlorperazine (Dopamine receptor antagonist):

  • Dosing: 5-10 mg every 6-8 hours; 25 mg suppository every 12 hours 2
  • Side effects: CNS depression, anticholinergic effects, extrapyramidal symptoms 2
  • Contraindications: History of leukopenia or neutropenia, dementia, glaucoma, or seizure disorder 2

• Metoclopramide:

  • Less effective than ondansetron in preventing vomiting beyond 6 hours 1
  • Higher incidence of side effects compared to ondansetron 1

Adjunctive Therapies

Sedatives

• May be considered when anxiety contributes to coughing paroxysms:
  • Alprazolam: 0.5-2 mg every 4-6 hours 2
  • Lorazepam: 0.5-2 mg PO/IV/sublingual every 4-6 hours 2
  • Diphenhydramine: 12.5-25 mg every 4-6 hours during episodes 2
  • Caution: These medications can cause CNS depression and should be used carefully in elderly patients or those with comorbidities 2

Hydration and Supportive Care

• Ensure adequate hydration and fluid repletion 2
• Check and correct any electrolyte abnormalities 2
• Consider antacid therapy (H2 blockers or proton pump inhibitors) if the patient has difficulty distinguishing heartburn from nausea 2

Special Considerations

For Severe or Refractory Cases

• Consider combination therapy with multiple agents using different mechanisms of action 2
• When oral route is not feasible due to ongoing vomiting, use rectal or IV administration 2
• For severe paroxysmal cough causing post-tussive vomiting, consider short-course corticosteroids (prednisone 30-40 mg daily for a short period) when other causes have been ruled out 2

For Pertussis-Related Post-Tussive Vomiting

• If whooping cough is suspected (paroxysms of coughing, post-tussive vomiting, inspiratory whooping sound for ≥2 weeks), treat with macrolide antibiotics 2
• Isolate patient for 5 days from the start of antibiotic treatment 2
• Note: Long-acting β-agonists, antihistamines, corticosteroids, and pertussis Ig are not recommended for whooping cough 2

Implementation Strategies

• Consider routine around-the-clock administration rather than PRN dosing for persistent vomiting 2
• Reassess treatment efficacy after 24 hours and adjust therapy as needed 2
• For breakthrough vomiting, add an agent from a different drug class 2

Key Pitfalls to Avoid

• Failing to identify and treat the underlying cause of cough (UACS, asthma, GERD, etc.) 2
• Using oral medications when the oral route is not feasible due to ongoing vomiting 2
• Overlooking potential drug interactions or contraindications, especially with sedatives 2
• Neglecting to monitor for side effects, particularly with dopamine antagonists (extrapyramidal symptoms) 2