Cough

What Is A Cough? What Causes A Cough?

A cough, also known as tissus is a sudden reflex humans and many animals have to clear the throat and breathing passage of foreign particles, microbes, irritants, fluids and mucus - it is a rapid expulsion of air from the lungs. Coughing can be done deliberately or involuntarily.

There are three phases to a cough reflex:

• An inhalation (breathing in)
• A forced exhalation with the glottis closed. The glottis is in the area where the vocal cords are located, it is the middle part of the larynx.
• An explosive release of air when the glottis opens. A cough typically has a characteristic sound.

If somebody coughs a lot it can be a sign of a disease. Germs rely on coughs to spread to new hosts. In the majority of cases, a cough is caused by an infection in the respiratory tract, but it can also be due to pollution, GERD (gastroesophageal reflux disease), chocking, chronic bronchitis, a tumor in the lung, heart failure, some drugs (e.g. ACE inhibitors), post-nasal drip, and smoking.

A doctor will focus on treating the cause of the cough, for example, if it is due to an ACE inhibitor it may be discontinued. Codeine, dextromethorphan and other cough suppressants are often used by people with coughs, however, studies have shown that they are not really effective.

As a cough is a natural reflex, suppressing it might have a negative effect.

Classification of coughs

Acute cough - this is a cough of sudden onset that lasts up to three weeks.

Subacute cough - this type of cough persists for between three and eight weeks.

Chronic cough - this type persists for over eight weeks.

Productive cough - a cough that brings stuff up, such as sputum.

Dry cough - a cough that brings nothing up

Nocturnal cough - only occurs at night.

What are the causes of a cough?

The majority of coughs are caused by viruses and clear up without treatment.

Causes of acute cough - in most cases the infection is in the upper respiratory tract and affects the throat, known as an URTI (upper respiratory tract infection). Examples include flu, the common cold and laryngitis.

If it is an LRTI (lower respiratory tract infection), the lungs are infected and/or the airways lower down from the throat (windpipe). Examples include bronchitis and pneumonia (rare).

 An acute cough can also be caused by hay fever. According to the National Health Service, UK, an acute cough might be the initial sign of a chronic disease.

Causes of chronic cough - as mentioned at the beginning of this article, a chronic cough may be caused by smoking, mucus dripping down the throat from the back of the nose (nasal drip), GERD (gastro-esophageal reflux disease), asthma, and some medications (e.g. ACE-inhibitors).

Chronic coughs in children may be caused by whooping cough, respiratory tract infections, GERD and asthma.

Less common causes of chronic cough include TB (tuberculosis), a clot in the lung (pulmonary embolism), or tuberculosis.

Diagnosing a cough

If a good doctor decides your cough is caused by the common cold or flu, you most likely will be told to rest, drink plenty of fluids and let it run its course. In the majority of cases such coughs clear up after a week or two.

A cough caused by a viral infection that persists for more than a couple of weeks will probably require medical attention. The doctor may order some diagnostic tests, such as a chest X-ray, a sample of phlegm may be sent to a laboratory for analysis to determine what is causing the infection. The patient may be asked to breath in and out of a tube attached to a machine, it helps the doctor determine whether the airways have narrowed (this test is called a spirometry).

If asthma is diagnosed, the patient may be prescribed an asthma medication.

Sometimes a general practitioner (primary care physician) may refer the patient to a respiratory specialist.

What are the treatment options for a cough?

The best way to treat a cough caused by a viral infection is to let your immune system deal with it - generally, such coughs clear up on their own. According to the National Health Service, UK, a homemade remedy with honey and lemon is as good, if not better than most OTC products sold in pharmacies.

Honey - it coats the throat, resulting in less irritation and possibly less coughing. Honey is a demulcent (something that soothes).

Cough medications - some may help associated symptoms, such as fever or a stuffy nose. However, there is no compelling evidence that cough medicines are effective.

Public health authorities in many countries today advise their people not to give OTC (over-the-counter) cough and cold medications to children less than six years of age ("Cough And Cold Medicines Not For Children Under 6, Says Health Canada").

Cough suppressants - these suppress the cough reflex and are generally only prescribed for dry cough. Examples include pholcodine, dextromethorphan and antihistamines.

Expectorants - these help bring up mucus and other material from the trachea, bronchi and lungs. An example is guaifenesin (guaiphenesin), which thins the mucus and also lubricates the irritated respiratory tract, thus promoting drainage from the lungs.