Why do infants and children vomit when they cough and how can it be prevented in pediatric patients?

Why Infants and Children Vomit When They Cough

Post-tussive (after-cough) vomiting in children occurs because forceful paroxysmal coughing triggers the vomiting reflex, and the most important clinical implication is that this presentation strongly suggests pertussis (whooping cough), which requires specific testing and treatment. 1, 2, 3

Physiological Mechanism

The vomiting occurs through a direct mechanical pathway:

• Paroxysmal coughing creates forceful expiratory bursts that increase intra-abdominal pressure and stimulate the vomiting center in the medulla, causing gastric contents to be expelled 3, 4
• Children have a more sensitive gag reflex and smaller airways than adults, making them more susceptible to this reflex activation during intense coughing episodes 4
• The cough-vomit sequence is particularly prominent in pertussis, where repeated rapid coughing paroxysms without adequate inspiration between coughs directly trigger emesis 1, 3, 5

Critical Diagnostic Consideration

When a child presents with cough and vomiting, pertussis must be your primary consideration:

• Post-tussive vomiting has high specificity (77.7% in adults, 66.0% in children) for pertussis, meaning when present, it strongly suggests this diagnosis 3, 5
• Testing for Bordetella pertussis should be undertaken when post-tussive vomiting is present, particularly if accompanied by paroxysmal cough or inspiratory whoop 1, 2, 5
• Do not wait for laboratory confirmation to initiate treatment—start macrolide antibiotics (preferably azithromycin) when pertussis is clinically suspected to prevent transmission 3, 5

Prevention Strategies

For Acute Cough with Vomiting

Immediate interventions to reduce vomiting episodes:

• Ensure adequate hydration to thin secretions, which reduces cough intensity and subsequent vomiting 2, 6
• For children over 1 year, honey provides more relief than diphenhydramine or placebo and may reduce cough frequency 2
• Eliminate environmental tobacco smoke exposure, which exacerbates coughing 1, 2
• Use antipyretics to keep the child comfortable, as fever can worsen symptoms 2

For Pertussis-Related Post-Tussive Vomiting

Specific management approach:

• Initiate macrolide antibiotics early (azithromycin preferred) to reduce disease duration and prevent transmission, though antibiotics may not alter the clinical course if started after the paroxysmal phase begins 3, 5
• Antibiotics are most effective when started during the catarrhal phase (first 1-2 weeks when symptoms are nonspecific), but should still be given later to prevent spread 3
• Provide small, frequent feeds rather than large meals to minimize gastric distension that could trigger vomiting with coughing episodes 2

For Chronic Cough (>4 Weeks) with Vomiting

Systematic diagnostic approach:

• Obtain chest radiograph and age-appropriate spirometry to identify underlying causes 1, 2, 5
• Distinguish between wet/productive versus dry cough, as this determines the diagnostic algorithm 1, 2
• For chronic wet cough without specific pointers, treat with 2 weeks of antibiotics targeting Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis (amoxicillin first choice) 1, 2
• Do not empirically treat for asthma, GERD, or upper airway cough syndrome unless other features consistent with these conditions are present 1, 2

Common Pitfalls to Avoid

Critical errors in management:

• Do not dismiss post-tussive vomiting as simple gastroenteritis without considering pertussis, especially if cough is paroxysmal 2, 3, 5
• Do not assume adult cough etiologies apply to children—common adult causes like GERD are rarely the cause of pediatric chronic cough 1, 2
• Do not use acid suppressive therapy solely for chronic cough in children, as it is ineffective and potentially harmful 1
• Avoid chest physiotherapy, as it is not beneficial for cough-related vomiting 2

When to Escalate Care

Red flags requiring immediate attention:

• Respiratory rate >70 breaths/min in infants or >50 breaths/min in older children indicates severe respiratory distress 2
• Oxygen saturation <92% requires immediate intervention 2
• Bilious or bloody vomiting, altered sensorium, or severe dehydration necessitate urgent evaluation 4
• Review within 48 hours if symptoms are deteriorating or not improving 2