Phlegm - Everything you need to know about lung mucus


What is Phlegm? Phlegm is a kind of mucus secreted by glands in the lungs. Normally, phlegm serves to attract and collect foreign particles and debris in the lungs so it can be expelled into the throat. Typically the phlegm is then digested in the stomach but sometimes may be coughed up. Different illnesses or conditions can change the amount of phlegm produced in the lungs as well as its texture and colour.

Diagnosis of Phlegm

Depending on the cause of excess phlegm production, the colour of the phlegm may vary. Colours range from clear to white, green, yellow, brown. pink and red. The colour of the phlegm can give a good indication of what may  be causing excess production.

Symptoms of Phlegm

Phlegm is usually a symptom of something else, but wet coughing is a common sign that you are producing more phlegm than normal.

Causes of Phlegm

Different colours of phlegm can be used to potentially identify an underlying cause. Colours and causes of phlegm include:

  • Clear - Allergic Rhinitis, Bronchitis and Pneumonia 
  • White - Bronchitis, Chronic Obstructive Pulmonary Disease (COPD), Congestive Heart Failure, Vital or Bacterial infection (Cold, Flu, COVID-19)
  • Green/Yellow - Bronchitis, Pneumonia, Sinusitis and other Viral Infections (including COVID-19)
  • Brown: Bronchitis, Pneumonia, Smoking
  • Pink/Red - Pink or red phlegm indicates that there is blood in your lungs and you should seek medical attention immediately, as it can be a sign of many serious conditions, including Congestive Heart Failure, Lung Cancer, Pneumonia, Pulmonary Embolism and Tuberculosis.

The texture of phlegm can also indicate illness, with thicker phlegm usually a sign that an infection is progressing, and frothy, or “mucoid” phlegm often being a sign of pulmonary problems. 


If you’re coughing up all the colours of the rainbow, the easiest and fastest way to book an appointment with a doctor is to do it online with MyHealth1st. The MyHealth1st booking platform is available 24/7, so you never have to wait until business hours to book your next doctor’s appointment.


Phlegm Self Care

Feeling “phlegmy” when you’re sick is common and can be controlled with over the counter medications like expectorants - medicines that help you cough up phlegm. 

See a Doctor If:

If your phlegm is clear, yellow or green, you can usually wait a few days to see if it clears up without having to worry about seeing a doctor. If the phlegm persists for more than a week or so, you may want to see a doctor for prescription cough medicine or antibiotics.

If your phlegm is brown, pink or red you should immediately see a doctor.

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