A wet cough occurs as a result of excess fluid or mucus in the airways.
A range of conditions can cause a wet cough, including respiratory infections,
Inflammation of the airways causes them to narrow and secrete thick mucus, or phlegm, which clogs the small airways, causing the characteristic cough of bronchitis, wheezing, and shortness of breath.
The cough may produce sputum, which is phlegm coughed up from the lungs.