Cough is a reflex that is stimulated by irritation of the respiratory mucosa in the lungs, trachea or the pharynx. It is often a reaction to infection or contamination of the respiratory tract and is a protective mechanism to clear the airways.
It is sometimes desirable to encourage a cough, and sometimes to suppress it.
A cough may be broadly described as either productive – i.e. producing sputum- or non-productive (dry), with no sputum.
A non-productive cough may be described as dry, tickly or irritating. It produces no sputum, and generally the cause is unlikely to be a bacterial infection. Non-productive coughs are irritating, not only to the patient, but also to those who live or work with him or her. It can be caused by damage to the upper respiratory tract, smoking, a dry atmosphere, air pollution or a change in temperature. It may also be a feature of some serious conditions such as asthma or even lung cancer, or an adverse reaction to certain drugs.
Clear or white sputum can generally be considered as being of little significance, unless produced in copious amounts.
Thick yellow, green or brown sputum or foul- smelling sputum suggests a lower respiratory (lung) infection, such as bronchitis, but this is not always the case and sometimes may just represent debris being cleared from the airways. Clear or straw coloured sputum may be seen in disorders of allergic origin, such as some forms of asthma.
Blood in the sputum may be seen as either spots or streaks and may sometimes colour the sputum brown. It should always be investigated further as it may be a sign of pulmonary embolism, tuberculosis, bronchitis or lung cancer.
Patients with pneumonia typically produce rust-coloured sputum at first, which may progress to be bloodstained.
The onset of a cough may be sudden, acute and devastating, causing collapse or serious illness, as is the case in pneumonia. More often, however, the onset is slower and less dramatic. If it occurs at night and is accompanied by catarrh it may be caused by a postnasal drip. The cough of bronchitis or bronchiectasis is worse on awakening.
Most coughs are worse at night, but special care should be taken to note a dry night-time cough in children, which could be due to asthma, or a night-time cough and breathlessness in adults, which can be a sign of pulmonary congestion (a possible sign of heart failure).
A large range of treatments, (syrups or pastilles) are available over the counter from your pharmacy, and your pharmacist will be able to advise you as to which is best to treat your symptoms.