What is cough?
Cough is a symptom with an underlying cause. It is a reflex initiated by our body to protect the lower breathing tract from harmful agents that encroach on its territory.
Types of cough
Broadly, cough can be productive i.e. associated with production of phlegm, or dry. It can acute, which is short lived and usually accompanies a throat or chest infection. Alternatively it can be chronic when it persists for more than 8 weeks.
Causes of cough
There are numerous reasons for a cough. The commonest reasons are outlined below:
Common cold is due to a virus. It not only affects the nose, but also affects the lower respiratory passage. Inflammation of the throat, larynx (voice box), wind pipe (trachea), and the small breathing passages called bronchi leads to an irritation and a cough.
This cough is acute and also short lived. As the cold subsides, so does the cough, usually lasting no more than a few weeks.
A chest infection can accompany or follow a cold. When the bronchi are inflamed the term used is bronchitis.
Irritation of the bronchial lining causes coughing. The lining is also rich in glands that pour out mucus, and this is coughed up as phlegm. Initially it may be thin and colourless, but as the inflammation continues it can become thick and yellow. In addition, irritation of the bronchi can also cause spasm which can be heard as a wheeze.
Again, most chest infections are short lived and the accompanying cough with or without phlegm should subside in a few weeks.
Other chest conditions
There are several chest conditions that give rise to a cough. These are not necessarily due to an infection. Most common conditions in this group include uncontrolled asthma, and bronchiectasis.
In asthma there is constriction of the bronchi. This may or may not be associated with an allergy. Constriction of the bronchi leads to coughing accompanied with wheezing. The cough may or may not productive, and can come on when lying down or worse at night disturbing sleep. The cough is chronic unless asthma treatment is initiated and optimised.
Bronchiectasis is caused by scarring of the small passages within the lungs called bronchi. It leads to their dilatation. Mucus produced within these passages lays stagnant inviting infection. It irritates the lining causing a cough, which is productive. This condition cannot be cured, and hence the cough is chronic. However, treatment can be optimised so as to reduce the severity of cough, and stasis of mucus which prevents frequent infections.
Post nasal drip (also see section on Catarrh)
Inflammation of the nose and sinuses leads to an excessive production of mucus. The normal path by which it is cleared is via the back of the nose or postnasal space. The lower airway lies within this path, and can be irritated leading to coughing. This cough can be productive.
Addressing the cause of the postnasal drip should help relieve the cough.
As the name suggests, in this condition acid from the stomach comes up into the throat. The throat houses our voice box, which can be irritated due to this reflux of acid leading to a cough.
The cough is dry and more noticeable when the person lies down or at night after a meal.
What is the treatment for cough?
Acute cough subsides as the condition resolves with time. This is usually a few weeks. Chronic cough that lasts more than 8 weeks needs attention. A good history and examination are essential. Endoscopy to examine the nose, and throat are required to rule out untoward causes of cough and diagnose a problem within the airway passages.
Treatment is dependent on the diagnosis. Opinion from a chest specialist is often required as the problem may arise from the lower airways.