Quick answer. Haemoptysis means coughing up blood or blood-stained phlegm from the lungs or airways. Even a small amount should always be checked by a doctor, because it can be the first sign of a serious condition – a chest infection, bronchiectasis, tuberculosis, a blood clot on the lung, or lung cancer. It helps to work out whether the blood is truly from the lungs rather than the nose, mouth or from vomiting. Coughing up a large amount of blood, or blood with severe breathlessness or chest pain, is a medical emergency – call 995. In Singapore and the region, TB remains an important and treatable cause to rule out.
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In a medical emergency, or for severe or sudden symptoms such as breathing difficulty, chest pain, fainting or stroke signs, call 995 immediately.
Seeing blood when you cough is alarming – and the right response is simple: always get it checked, and treat heavy bleeding as an emergency.
Emergency red flags – when to call 995 or go to A&E
Some episodes cannot wait for a clinic appointment. Call 995 or go straight to the nearest Accident & Emergency (A&E) department if you are:
- Coughing up a large amount of blood – more than a few spots or streaks, for example filling a cup, or blood that keeps coming.
- Coughing up blood together with severe or worsening breathlessness.
- Coughing up blood with chest pain or upper-back pain.
- Feeling dizzy, light-headed, faint or clammy, or your heart is racing.
- Turning pale or blue around the lips, or struggling to speak in full sentences.
Just as important: any coughing up of blood, even a single small streak that stops on its own, should be assessed by a doctor promptly – do not ignore it or wait to see if it comes back. If you are unsure how much is too much, treat it as serious and seek help.
What it is – and why it always needs checking
Haemoptysis is blood coughed up from the respiratory tract – the lungs, the airways (bronchi) or the windpipe (trachea). It may appear as a few bright-red flecks streaking clear or coloured phlegm, as blood-stained sputum, or occasionally as larger volumes of frank blood. The amount does not always match the seriousness of the cause: a small, persistent streak can be the first warning of a treatable but important illness, while a one-off streak during a heavy cold may be minor. Because you cannot tell the cause from the appearance alone, every episode deserves a proper assessment, even if the bleeding settles quickly.
Telling it apart from other bleeding
Not all blood that appears in the mouth comes from the lungs, and sorting this out early guides the right tests. Try to notice where the blood seems to come from:
- From the lungs or airways (true haemoptysis): usually brought up by coughing, often bright red and frothy, and mixed with sputum or bubbles of air.
- From the nose or mouth: a nosebleed, bleeding gums, or a mouth or throat cut can trickle back and be spat out, mimicking haemoptysis. There is often no cough, and you may feel blood dripping at the back of the nose or throat.
- From the stomach (vomiting blood, or haematemesis): this comes up with retching or vomiting rather than coughing, is often darker red or brown, sometimes like coffee grounds, and may be mixed with food.
If you genuinely cannot tell the difference, it is safest to treat it as haemoptysis and get it checked. Noting the colour, the amount, and whether it came with coughing or vomiting will help your doctor.
Common causes
Most cases are caused by inflammation or infection of the airways rather than something rare. The commonest causes include:
- Chest infections and acute bronchitis – by far the most frequent reason. Vigorous coughing can irritate inflamed airways enough to streak the phlegm with blood.
- Pneumonia – a deeper lung infection, which may also cause fever, breathlessness and coloured phlegm.
- Bronchiectasis – permanently widened, scarred airways that trap mucus and infection, and can bleed. See our guide to bronchiectasis.
- Tuberculosis (TB) – an important, locally relevant cause. TB remains present in Singapore and the wider region, is a notifiable disease, and is curable with a proper course of treatment. It can cause a lingering cough, weight loss, night sweats and blood-stained phlegm. See tuberculosis.
Serious causes to consider
Because some causes are dangerous but treatable when caught early, doctors always keep these in mind:
- Lung cancer – even small, repeated amounts of blood in the phlegm can be an early sign, particularly in current or former smokers and in older people. This is one of the main reasons haemoptysis is never dismissed. See lung cancer.
- Tuberculosis – noted above; it can present with haemoptysis and needs specific tests and treatment.
- A blood clot on the lung (pulmonary embolism) – suspect this when blood is coughed up with sudden breathlessness, sharp chest pain and a fast heartbeat. It is a medical emergency. See our guide to pulmonary embolism.
- Bronchiectasis – damaged airways that bleed recurrently.
- Clotting problems and blood-thinning medicines – people taking anticoagulant or antiplatelet medicines, or with a bleeding tendency, may bleed more readily from the airways.
Less commonly, certain heart, blood-vessel and autoimmune conditions can also cause haemoptysis.
Who is at higher risk
Coughing up blood can happen to anyone, but some people are more likely to have a serious underlying cause:
- Smokers and former smokers – higher risk of lung cancer, bronchitis and other lung disease.
- Older adults – a greater chance of significant underlying illness.
- People with known or possible TB exposure – a previous history of TB, close contact with someone who has TB, or travel from areas where TB is common.
- People on blood thinners or with a known bleeding or clotting disorder.
- People with existing lung conditions such as bronchiectasis or long-standing chest disease.
How it is assessed
The goal of assessment is to confirm the blood is coming from the lungs and to find the cause. A doctor – a GP or polyclinic doctor first, and often a respiratory physician – will usually arrange a combination of the following, depending on your history:
- History and examination – questions about the amount and colour of blood, how long it has lasted, your smoking history, any weight loss, fevers or night sweats, medicines you take, and TB contact; plus listening to your chest.
- Chest X-ray – often the first imaging test to look for infection, fluid, or a shadow.
- Blood tests – to check for infection, anaemia from blood loss, clotting, and general health.
- Sputum tests, including for TB – examining coughed-up phlegm for infection and specifically for tuberculosis.
- A CT scan of the chest – a more detailed picture that can show causes an X-ray may miss.
- Bronchoscopy – a thin camera passed into the airways to look directly and, if needed, take samples or help control bleeding.
Why even small amounts should be checked
It is tempting to ignore a single streak of blood, especially if you feel otherwise well and it does not return. But the appearance and volume do not reliably tell you whether the cause is trivial or serious – a minor amount can be the earliest sign of lung cancer, TB or another treatable condition. Checking it early means problems are found when they are most treatable, and it offers reassurance when the cause turns out to be minor. Prompt assessment is always the safer choice.
Treatment
There is no single treatment for haemoptysis itself – care is directed at the underlying cause. That might mean antibiotics for a chest infection or pneumonia, a full course of anti-TB treatment for tuberculosis, treatment for a blood clot, management of bronchiectasis, or specialist care for lung cancer. If a blood-thinning medicine is contributing, your doctor may review it. Heavy bleeding is treated as an emergency and may need procedures to stop it. If you smoke, stopping smoking is strongly advised and improves outcomes for almost every lung condition.
When to see a doctor
See a doctor promptly for any coughing up of blood, even a small streak – a GP, polyclinic doctor or respiratory physician can arrange the right tests. Seek care sooner if you also have a cough lasting more than a few weeks, unexplained weight loss, night sweats, fever, or breathlessness. Remember: coughing up a large amount of blood, or blood with severe breathlessness, chest pain, dizziness or feeling faint, is a medical emergency – call 995 or go to A&E. You can also read general information on lung and breathing symptoms on Singapore’s HealthHub.
Related respiratory & lung topics
- Pneumothorax (collapsed lung)
- Pulmonary (lung) nodule
- Lung function tests & spirometry
- Whooping cough (pertussis)
- Bronchiolitis in children
- Mesothelioma
- Occupational lung disease
- Interstitial lung disease (ILD)
- Pulmonary rehabilitation
- COPD
- Asthma
- Respiratory physicians in Singapore
Sources
- NHS — coughing up blood (haemoptysis): what it is, urgent vs emergency guidance, common and serious causes.
- Cleveland Clinic — coughing up blood: causes, when to seek care, distinguishing lung bleeding from other sources.
- American Family Physician — hemoptysis evaluation and management: investigations (CXR, CT, bronchoscopy).
- MOH Singapore / CDA — tuberculosis: a notifiable and curable disease and an important cause to consider in this region.