What causes posttussive emesis (vomiting after coughing)?

What Causes Posttussive Emesis

Posttussive emesis (vomiting after coughing) is primarily caused by vigorous paroxysmal coughing that triggers the vomiting reflex, most classically seen in pertussis (whooping cough) infection, but also occurs in asthma and other conditions causing severe coughing paroxysms. 1

Primary Mechanism

The fundamental cause is mechanical stimulation of the vomiting reflex during intense coughing episodes:

• Paroxysmal coughing generates forceful expiratory bursts that increase intra-abdominal and intrathoracic pressure, directly triggering emesis 1, 2
• The cough must be paroxysmal in nature (occurring in spasms or bursts) rather than continuous to produce this effect 1
• This is a physical consequence of the coughing itself, not a separate disease process 1

Most Common Causes by Condition

Pertussis (Bordetella pertussis infection)

This is the classic and most important cause to identify:

• Posttussive emesis is a hallmark symptom of the paroxysmal phase of pertussis, which lasts 4-6 weeks 1, 2
• When cough persists >2 weeks and is accompanied by posttussive vomiting, paroxysms, and/or inspiratory whoop, pertussis should be diagnosed unless proven otherwise 1, 2
• Posttussive vomiting has high specificity (77.7%) but low sensitivity for pertussis in adults, meaning when present it strongly suggests the disease 2
• In children, posttussive vomiting has moderate sensitivity (60%) and specificity (66%) for pertussis 2, 3
• Critical pitfall: In infants <2 years, vomiting or apnea is more commonly seen than the typical whooping sound, and the classic whoop is usually absent in adults 1

Asthma

An underrecognized but important cause in children:

• Among children with physician-diagnosed asthma, 56% report posttussive emesis 4
• Children with posttussive emesis are 7.9 times more likely to have asthma than those without it (95% CI, 5.2-12) 4
• When a child presents with cough and posttussive emesis, asthma should be strongly considered in the differential diagnosis 4

Postinfectious Cough (Non-Pertussis)

Following viral respiratory infections:

• Caused by extensive disruption of airway epithelial integrity and widespread inflammation with mucus hypersecretion 1
• The vigorous coughing from transient airway hyperresponsiveness can trigger vomiting 1
• This is a subacute cough lasting 3-8 weeks with normal chest radiograph 1

Other Contributing Factors

• Gastroesophageal reflux disease (GERD) may be both a cause and complication of vigorous coughing 1
• Upper airway cough syndrome (previously postnasal drip) from persistent nasal/sinus inflammation 1

Diagnostic Approach

When evaluating posttussive emesis, use this algorithm:

1. Duration assessment: If cough >2 weeks with posttussive vomiting, suspect pertussis first 1, 2

2. Pattern recognition: Look for the pertussis triad:

   • Paroxysmal cough (93.2% sensitivity) 2
   • Posttussive vomiting (77.7% specificity) 2
   • Inspiratory whoop (79.5% specificity, but often absent in adults) 2

3. Age-specific considerations:

   • Infants: May present with apnea and minimal cough rather than classic symptoms 2
   • Children: Consider asthma if pertussis ruled out 4
   • Adults/vaccinated individuals: Whoop frequently absent; illness may be milder 2

4. Testing strategy:

   • Order nasopharyngeal PCR or culture immediately when pertussis suspected 1, 3
   • Do not wait for laboratory confirmation to start treatment if clinical suspicion is high 2, 3

Critical Clinical Pitfalls to Avoid

• Never dismiss pertussis in vaccinated individuals—the illness can be milder with absent whoop but still cause posttussive emesis 2
• Do not rely on leukocytosis/lymphocytosis—these classic lab findings are frequently absent 1, 2
• Patients are most infectious during the catarrhal stage (first 1-2 weeks) when symptoms are nonspecific and before posttussive emesis develops 2
• Absence of fever does NOT exclude pertussis in children 3
• In infants with posttussive emesis and pertussis, provide frequent small feedings immediately after coughing episodes to prevent aspiration and maintain nutrition 3, 5