One airway, one disease
Asthma and seasonal allergies are related conditions linked by a common airway. The air we breathe in passes through our nose (at the start of our airway) and continues down the airway into the lungs. Asthma and seasonal allergies cause problems with our breathing by obstructing the free passage of air along this path.
With asthma, the breathlessness and wheezing is caused by a narrowing of the bronchioles (small branched airways in the lungs). Inflammation of the membranes of these small airways may cause an increase in the production of mucus, making the obstruction worse; the dry cough that develops is an attempt to clear the airways.
With seasonal allergies, the obstruction occurs in the upper section of the airway (in the nose). A blocked and runny nose occurs when the membranes of the nose become inflamed. In the same way as coughing is an attempt to clear the obstruction in the lower part of the airway, sneezing is an attempt to clear the mucus from the upper part.
Asthma and seasonal allergies:
two symptoms, “one airway”
Asthma and seasonal allergies are linked by “one airway”
Source: Journal of Allergy and Clinical Immunology.