20 December, 2006


The inside surface of your lungs is normally covered with a thin layer of slimy mucus. The mucus lubricates the airways and helps in the removal of foreign particles that might have been inhaled, such as dust or bacteria. Additional mucus is produced during infection or when there is airway irritation, from smoke or dust, for example.

The airways are normally cleared of excess mucus and foreign particles by a combination of coughing and mucociliary clearance, which is the coordinated movement of tiny hairs (cilia) that project into the mucus-lined airways. The cilia move the mucus and particles upwards like an escalator or a Mexican wave.

An increase in mucus production is a common symptom of acute bronchitis, influenza and the common cold. Mucus production usually returns to normal once the infection has cleared up.

People with certain chronic lung diseases are regularly troubled by too much mucus (or phlegm [1]). Diseases in which mucus is an ongoing problem include chronic bronchitis (one of the COPD group of diseases [2]), bronchiectasis and cystic fibrosis.

This can result from one or more of the following

  • mucus which is too thick or sticky

  • over-production of mucus, causing a thicker layer in the airways

  • ongoing untreated infections

  • malfunction of the cilia (tiny hairs)

  • ineffective coughing.

Insufficient physical activity will make any of these situations even worse.

Excessive mucus in the lungs causes three main problems

1. Coughing
You cough and cough as your airways try to expel the excess mucus. This makes you tired out and short of breath. Your coughing keeps you and your family awake at night. You might even crack a rib or develop a weak bladder from all that coughing.

The cough may not work – you feel there's mucus, and you can hear it moving in your airways when you breathe and cough, but you just cannot seem to get it all the way up. The mucus may be thick or sticky.

2. Blockage
The mucus can block the smaller airways (breathing tubes) making you more breathless than usual, and can possibly lead to the collapse of a section of the lung. Mucus plugs are more likely when there is already some degree of inflammation or narrowing of the airways. This happens when there is an infection, irritation or scarring in the lung or the mucus is too thick.

3. Repeated infections
Excess mucus that remains in your lungs can make you more likely to get repeated respiratory infections like bronchitis or can lead to more severe infections, like pneumonia.

While normal mucus is clear, it sometimes becomes coloured - white, yellow, brown or green. After very vigorous coughing you may even see a few spots of blood in the mucus. A change in the colour of your mucus may mean you are developing an infection. Consult your general practitioner or respiratory specialist if your mucus changes colour or you see blood in it.

Better still, develop an action plan with your doctor, setting out what you should do if you feel unwell, more breathless or there are signs of infection.

[1] Mucus is the lubricating coating found in many parts if your body, including lungs, mouth, nose, vagina. Phlegm is the name given to the mucus found in your lungs. Sputum is what you manage to spit up through airway clearance. It contains both phlegm as well as some saliva (on its way through your mouth).
[2] COPD Chronic Obstructive Pulmonary Disease


Anonymous said...

I moved to a hotter climate from a temperate one two years ago and have been plagued with periods where my overproduction of mucus from my lungs and in my throat leave me gagging on it. Anyone any thoughts on what might be causing it and how i can alleviate the problem

Meifu said...

This a very informative blog, thanks!

Sharon said...




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Anonymous said...

I'm a nurse and this was short,sweet and to the point.