Updated 23 August 2019

Coughing up blood: when should you be concerned?

Coughing up blood can be a sign that something is seriously wrong, but it isn't always a reason to panic. Find out when to worry, and what could be wrong.

Coughing up blood (haemoptysis), or blood in your sputum should always be treated as a warning sign.  Although it may be a sign of something sinister, it can also be due to something very common and treatable like a chest infection.  

Common causes of coughing up blood

In 70 – 90% of cases, coughing up blood is due to infections like bronchitis, pneumonia and tuberculosis.  In children, an inhaled foreign body (like a small toy) could also be the cause a bloody cough. 

 In all cases, one should be examined by a doctor as it may also indicate more serious, less common, causes such as:

  • Lung cancers
  • A blood clot in the lungs (pulmonary embolism)
  • Inflammation of the blood vessels of the lung
  • Bleeding and clotting disorders

Different ways in which coughing up blood may present

1. Streaky (lines of blood in phlegm)
Infections like bronchitis and pneumonia present in this way. If it persists and is associated with weight loss and night sweats it may be due to TB. 

Tuberculosis (TB) is highly prevalent in South Africa and is a common cause of coughing up blood.  If you experience any weight loss, night sweats and persistent coughing, have yourself tested for TB.  Remember, you can contract TB anywhere – even when on the train or shopping as it is spread through the cough droplets of an infected person.

2. Pink, frothy sputum
This is very suggestive of fluid overload in the lungs (pulmonary oedema). This can be due to heart failure (like after a heart attack) or kidney failure. Considered an emergency, when coughing up pink frothy sputum you should seek help immediately as this can be potentially fatal.

3. Frank blood
Coughing up what looks like pure blood is a concerning sign. It can be classified as follows:

(the volumes are only guides  - no precise volume definitions are agreed on by researchers and cases should be individualised)             

Minor (less than 5ml in 24 hours)  
This is usually caused by TB, severe infections and cancers.

Massive (more than  2 cups in 24 hours or more than half a cup per hour, or more than 50ml at one time)
This can be due to a cancer that, due to its continuous growth, broke through a blood vessel. Where TB caused big cavities in the lung, blood vessels may also be damaged, leading to very significant bleeding.

When is coughing up blood dangerous?

1.            In the case of massive amounts of blood (see above)
2.            When coughing up blood is associated with back or chest pain
3.            If you notice weight loss or fatigue
4.            When you have a strong smoking history
5.            When you are short of breath (even at rest)

How do you know if someone is coughing up blood or vomiting blood? It is very important to distinguish between coughing up blood and vomiting blood. When coughing up blood the blood comes from the respiratory system, while vomiting blood indicates bleeding from the stomach or oesophagus or even the intestines.  This is how you know the difference:

difference between vomiting and coughing blood

When noticing blood when coughing, best would be to speak to your doctor. 

Read more:

Khayelitsha clinic leading the way in TB 

Can you catch TB from animals 

What's your diagnosis: Bloody semen

Image: Man coughing severely by Shutterstock 


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Ask the Expert

Cough Expert

Professor Keertan Dheda has received several prestigious awards including the 2014 Oppenheimer Award, and has published over 160 peer-reviewed papers and holds 3 patents related to new TB diagnostic or infection control technologies. He serves on the editorial board of the journals PLoS One, the International Journal of Tuberculosis and Lung Disease, American Journal of Respiratory and Critical Medicine, Lancet Respiratory Diseases and Nature Scientific Reports, amongst others. Read his full biography at the University of Cape Town Lung Institute.

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