After infection by B. pertussis occurs, patients are susceptible to complications such as pneumonia, seizures, and encephalopathy. The most common complication is secondary bacterial pneumonia. This is also the cause of most pertussis-related deaths.
Seizures and encephalopathy (diffuse disorder of the brain) are neurological complications that may occur due to the hypoxia induced by coughing. Severe paroxysms may also cause pressure effects in the body, resulting in complications such as pneumothorax, epistaxis, subdural hematoma, hernias, and rectal prolapse.
Less serious complications of B. pertussis include otitis media, anorexia, dehydration, urinary incontinence, rib fracture, and difficulty sleeping.
Infants are most at risk for acquiring pertussis-related complications.