Typical causes of a constant cough include asthma, gastroesophageal reflux disease, postnasal drip, and infections such as pneumonia or bronchitis. Doctors do not consider this cough as a disease by itself, but a symptom of an underlying condition, according to MedicineNet.
Asthma, a primary cause of a constant cough, is a condition that affects the airways, causing difficulty in wheezing or breathing, says MedicineNet. A cough from asthma occurs from an upper respiratory infection, and its effects aggravate when the patient exposes himself to cold air, notes Mayo Clinic.
Stomach acids may flow back into the esophagus, causing irritation that can result in shortness of breath and coughing, a condition called acid reflux or gastroesophageal reflux disease. This condition can also cause the lungs to inhale foreign substances, worsening the coughing and damaging the lung tissue, explains MedicineNet.
The nose can also produce extra mucus, causing the mucus to drip down the back of the throat, causing chronic coughing, a condition called postnasal drip, notes Mayo Clinic. Moreover, infections such as pneumonia and bronchitis are also common causes of this condition. They result from bacterial, viral or fungal infections. Infections from viruses do not respond to medication, and a viral upper respiratory infection in patients experiencing asthma leads to a constant cough even after the infection is over, as detailed by MedicineNet.