Coughing is an important defensive reflex. It is triggered by irritation in the airways and acts as a protective function of the body to clear our airways from irritants like dust, pathogens, harmful substances or foreign bodies. Coughing is also common symptom in different illnesses – in some less serious, such as the common cold, bronchitis, but also in some more serious ones, such as pneumonia, asthma, blood clots or fluid in the lung. The cough can be classified by duration (acute / subacute / chronic) or by whether it is associated with mucus/phlegm excretion (wet or productive) or not (dry or non-productive). Normally, our airways produce a small amount of mucus to keep them moist and to maintain a thin layer that lines the inside of the bronchi. However, during respiratory infections, for instance, mucus may be extensively produced, becoming very rubbery and difficult to cough up sputum/ phlegm. If this happens, it can help to liquefy and loosen it, in order to support expelling the secretion out of the airways, thereby clearing the congestion and making breathing easier. There are medicines available to support this, called mucolytics and expectorants. On the other hand, a dry cough does not bring up any mucus. This is why a dry cough may be treated with medicines that suppress the cough reflex.