Common causes of dry cough
A dry cough does not produce sputum. This is the reason why it is sometimes called nonproductive cough. A dry cough often develops at the end of a cold (infection). It can be a reaction to an irritant, such as dust or smoke. Numerous chemicals are used in medical research to trigger cough in experimental animals.
In humans, there are several causes of a dry nonproductive cough, such as:
– viral infection (such cough may last more than 2-3 weeks and the symptoms often get worse at night)
– bronchospasm (a dry cough, particularly at night, leads to additional CO2 losses and cause spasms in the bronchial tubes (bronchospasm) due to hypocapnia or low CO2 in the airways)
– allergic triggers (due to pollen, dust, fumes, perfume, various other chemicals and so forth)
– some medical drugs, e.g., ACE inhibitors which contain captopril, lisinopril, and enalapril maleate
– asthma (due to chronic inflammation in airways with accompanying wheezing, shortness of breath, and a feeling of tightness in the chest
– blockage of the airways by an object, such as food, powder, or a pill
Why could dry cough become chronic?
There many negative effects due to chronic coughing or coughing attacks. It reduces boxy oxygen levels due to losses of CO2 in the arterial blood. Traditional coughing (through the mouth) is a form of hyperventilation. As a result, low CO2 levels in the lungs causes more problems with oxygen delivery. Indeed, according to the laws of physiology, when we breathe more air at rest, we get less oxygen in body cells. In addition, low CO2 in the airways causes over-excited states of urge-to-cough receptors since CO2 is a powerful calmative and sedative of nerve cells. High or normal CO2 levels keep nerve cells calm, while low CO2 levels makes them irritable. This means that CO2 losses due to coughing cause more coughing.