Posttussive Vomiting in Pertussis

Clinical Significance and Diagnostic Value

• Posttussive vomiting is a highly specific clinical sign for pertussis, although it can occasionally occur with other severe coughing illnesses, according to the American Thoracic Society 1
• The presence of posttussive vomiting should immediately raise suspicion for pertussis infection in patients with persistent cough, as recommended by the Centers for Disease Control and Prevention 3

Diagnostic Performance

• In children, posttussive vomiting has moderate sensitivity (60.0%) and specificity (66.0%) for pertussis, as reported by the American Academy of Pediatrics 2
• In adults, posttussive vomiting has low sensitivity but high specificity (77.7%), meaning when present, it strongly suggests pertussis disease, according to the Infectious Diseases Society of America 3

Mechanism and Clinical Presentation

• Posttussive vomiting occurs because the violent, repetitive coughing paroxysms characteristic of pertussis trigger the vomiting reflex, as explained by the European Respiratory Society 1
• The coughing episodes lead to forceful expulsion of gastric contents, significant nutritional challenges, weight loss, and feeding difficulties, particularly in infants, as noted by the World Health Organization 4

Management Implications

• When posttussive vomiting is identified, initiate macrolide antibiotics (preferably azithromycin) immediately to prevent transmission to contacts, as recommended by the American Academy of Family Physicians 2
• Provide nutritional support with smaller, more frequent feeds to prevent aspiration and maintain nutrition, as suggested by the Academy of Nutrition and Dietetics 4