Coughing Up Blood or Blood in Phlegm | Chest Doctor London

Coughing up blood always needs to be assessed. That includes a single streak in your phlegm, and it includes times when you feel otherwise well.

Common explanations include a chest infection or irritation from heavy coughing. Other causes can be more serious, and there is no reliable way to tell the difference at home. A small amount of blood does not rule out an important underlying cause.

When to call 999

Call 999 or go to A&E immediately if:

• You are coughing up more than a few small spots or streaks of blood.
• You are coughing up blood and finding it difficult to breathe.
• You are coughing up blood with chest or upper back pain, or a very fast heartbeat.
• You feel faint, clammy or severely unwell alongside the bleeding.
• You are coughing up pink, frothy phlegm with sudden or severe breathlessness.

Recent surgery, a long journey or a period of immobility can increase concern about a blood clot when bleeding occurs alongside breathlessness or chest pain.

Do not drive yourself to A&E. Ask someone to take you or call 999 for an ambulance.

When to seek same-day advice

Ask for an urgent GP appointment or contact NHS 111 if you cough up even a few small spots, flecks or streaks of blood. This applies even if you feel otherwise well or think a chest infection caused it.

Tell the clinician if any of the following applies:

• You are aged 40 or over, particularly if you smoke or used to.
• You have lost weight without trying, or have night sweats.
• You have had a cough for more than three weeks.
• You have a fever alongside the blood.
• Your immune system is weakened.
• You have travelled somewhere with a high rate of tuberculosis, or have been in contact with someone who has TB.
• You take anticoagulant medication, such as warfarin, apixaban or rivaroxaban.

When to book a prompt appointment

After urgent advice, your clinician may recommend a prompt appointment for further assessment. This is particularly important if the bleeding recurs, continues after an infection has settled, or remains unexplained.

Even a single streak during a chest infection should be discussed with your GP or NHS 111. Do not wait several days before seeking initial advice, or wait for a private appointment if you have emergency symptoms.

What is haemoptysis?

Haemoptysis is the medical term for coughing up blood or blood-stained phlegm from the lungs and airways.

It is worth separating it from two things it is often confused with:

• Haematemesis. Vomiting blood, which comes from the stomach or gullet rather than the lungs.
• Pseudohaemoptysis. Blood from the nose, mouth, gums or throat that is then coughed or spat out and appears to have come from the chest.

These have different causes, and telling them apart is one of the first things a respiratory physician will try to establish.

Where is the blood actually coming from?

Blood in your spit does not always come from your lungs. Identifying its source helps guide the assessment.

From the lungs and airways

Blood coughed up from the chest may be bright red and frothy, often mixed through phlegm. It typically follows coughing. Its appearance can offer clues, but cannot confirm where it came from or how serious the cause is.

From the nose, sinuses or throat

Blood from a nosebleed, an irritated nose or an inflamed throat can trickle backwards and be cleared with a cough or spit. Clues that this may be happening include:

• The blood appears when clearing your throat rather than after a deep cough.
• You have recently had a nosebleed, or your nose has been dry, blocked or crusty.
• You have a heavy cold, sinusitis or catarrh.
• There is blood in the mucus you blow from your nose too.
• You have a sore throat, tonsillitis or bleeding gums after brushing.

Blood in mucus from the throat without a cough may come from the nose, mouth or throat. This is a possibility to assess, rather than a diagnosis to make at home.

From the stomach

Blood from the stomach may be dark brown or resemble coffee grounds, although it can also be bright red. It comes up with retching or vomiting rather than coughing, and may occur with nausea or abdominal pain.

Forceful vomiting can sometimes cause a tear in the lining of the gullet. Vomiting blood needs urgent medical assessment.

Because these sources can be confused, describing exactly what happened, whether you coughed or retched, and what the blood looked like is useful information for the clinician assessing you.

What the colour and pattern can suggest

None of these appearances is diagnostic on its own. Colour and timing cannot determine whether it is safe to wait for medical advice.

Appearance	What it may suggest
Bright red streaks in green or yellow phlegm	A chest infection or irritated airways are possible causes. Phlegm colour alone does not establish the cause.
A single speck or streak while otherwise well	A small surface vessel may have bled after coughing, but even a small amount needs urgent advice.
Bright red blood in a larger amount, with or without phlegm	Several airway or lung conditions can cause this. More than a few spots or streaks requires emergency assessment.
Pink, frothy phlegm with breathlessness	Possible fluid in the lungs. Sudden or severe breathlessness requires emergency care.
Rust-coloured or brownish phlegm	Can occur with pneumonia or older blood. Appearance alone cannot identify the cause.
Dark or almost black flecks	May reflect older blood or inhaled particles, but should not be dismissed without assessment.
Blood when clearing the throat in the morning	The nose, mouth or throat may be the source, although a lung cause cannot be excluded by timing alone.

Blood in phlegm in the morning

One possible explanation is blood coming from the nose or throat overnight. Mucus can collect at the back of the throat while you are lying down, and dry air can irritate the lining of the nose and throat. The first throat-clearing of the day may bring this mucus up.

That is a possible explanation, not a safe assumption. Conditions affecting the lungs, including bronchiectasis and tuberculosis, can also cause blood-stained phlegm. The time of day does not reliably distinguish between them.

Seek urgent GP or NHS 111 advice for blood in your phlegm, including when it appears only in the morning. Mention any recurring bleeding, fever, night sweats, weight loss or long-standing cough.

Causes of coughing up blood

Common causes

Chest infections. Acute bronchitis and pneumonia can inflame the airway lining and make it more prone to bleeding. Blood-streaked phlegm can occur during an infection, including an infection developing during or after flu.

Forceful coughing. Severe or prolonged coughing can damage small blood vessels in the airway lining. Even if this seems the likely explanation, blood in your phlegm should be checked.

Bronchiectasis. Permanently widened, damaged airways can trap mucus and become prone to infection and bleeding. Recurrent haemoptysis alongside regular phlegm production is a pattern that warrants assessment.

Nose, sinus and throat problems. Bleeding from these areas can be mistaken for blood coming from the lungs.

Less common but important causes

Lung cancer. Coughing up blood is one of the symptoms that can prompt investigation for lung cancer. See the section below.

Tuberculosis. TB can cause a persistent cough, blood in the phlegm, night sweats, weight loss and fever. It remains a possible diagnosis in the UK, particularly when there has been exposure to someone with TB or travel to an area where it is more common.

Pulmonary embolism. A blood clot in the lung can cause sudden breathlessness, sharp chest pain and coughing up blood. This requires emergency assessment.

Heart failure. Fluid building up in the lungs can cause breathlessness and sometimes pink, frothy phlegm. Sudden or severe symptoms require emergency care.

Anticoagulant medication. Warfarin, apixaban, rivaroxaban and similar medicines can make bleeding more likely or harder to stop. If you cough up blood while taking one of these medicines, seek urgent medical advice and tell the clinician which medicine you take.

Other causes include lung abscess, certain autoimmune conditions affecting the lungs and kidneys, inhaled foreign bodies, and fungal infection in previously damaged lungs.

Coughing up blood and lung cancer

This is a common worry when someone notices blood in their phlegm, so it deserves a straight answer.

Coughing up blood does not automatically mean lung cancer. Infections and airway irritation are other possible explanations, particularly when there has been a recent illness.

Haemoptysis is, however, an important symptom in lung cancer assessment. NICE guidance recommends a suspected cancer pathway referral for people aged 40 or over with unexplained haemoptysis. This is a reason for prompt investigation, not a diagnosis of cancer.

Features that raise concern include a current or past smoking history, blood that recurs, unintentional weight loss, a cough that has changed or persisted beyond three weeks, breathlessness and a hoarse voice.

Never smoking does not exclude lung cancer. Dr Chinegwundoh has a particular interest in earlier detection. Since 2024, he has been clinical lead on a predictive AI project with Johnson & Johnson and South West London ICB, aimed at identifying people at raised risk of lung cancer who fall outside standard screening criteria.

A normal chest X-ray does not rule out lung cancer. Some abnormalities may not be visible on an X-ray. If bleeding continues or returns after a clear result, further assessment is needed. Depending on the findings, this may include a CT scan.

How coughing up blood is investigated

The purpose of assessment is to identify the source of the bleeding and investigate possible underlying causes.

History and examination. The clinician will ask what the blood looked like, how much there was, how often it appeared and what you were doing at the time. They will also ask about smoking, medication, travel, weight changes and accompanying symptoms. Examination may cover the nose, mouth and throat as well as the chest.

Chest X-ray. This is often an initial investigation. How urgently it is arranged depends on the clinical assessment.

Blood tests. These may include a full blood count, clotting tests, inflammatory markers and kidney function tests.

Sputum tests. A sample of phlegm may be tested for infection, including specific testing for tuberculosis when indicated.

CT scan of the chest. A CT scan gives more detail than an X-ray and may be needed when bleeding persists, the X-ray is abnormal, or bronchiectasis or a tumour is suspected. A CT pulmonary angiogram may be used when a blood clot is suspected.

Bronchoscopy. A thin, flexible camera is passed into the airways, usually with local anaesthetic and sometimes sedation. This allows direct inspection and sampling. It may be used when further information or a biopsy is needed.

Lung function testing or an ear, nose and throat assessment may also be appropriate, depending on the findings.

Not everyone needs all of these tests. Investigations should answer a specific clinical question and be tailored to the individual.

Specialist assessment with Dr John Chinegwundoh

Dr John Chinegwundoh is a Consultant Respiratory Physician with more than 20 years of consultant experience. He spent four years as Clinical Director for Medicine at Kingston Hospital, serves as President of the Cambridge Medical Graduates’ Society, and leads a predictive AI project with Johnson & Johnson and South West London ICB focused on earlier detection of lung cancer.

Following initial urgent advice, a respiratory opinion may be particularly helpful when:

• Blood in the phlegm has occurred more than once.
• Blood persists after a chest infection has otherwise settled.
• A chest X-ray was reported as normal, but the symptom continues.
• You are aged 40 or over, or have ever smoked.
• You produce phlegm on most days, or have had repeated chest infections.
• Nobody has yet explained where the blood is coming from.

Assessment considers possible sources in the nose, mouth and throat as well as the lungs. Where imaging or other investigations are needed, these can be discussed and arranged as part of your care.

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If you are currently coughing up blood, seek urgent GP or NHS 111 advice first. For emergency symptoms, call 999 or go to A&E immediately.

Frequently asked questions

This page provides general information and is not a substitute for individual medical assessment. Follow the urgent and emergency advice above if you are coughing up blood.

References

• NHS: Coughing up blood (blood in phlegm)
• NHS: Anticoagulant medicines, side effects
• National Institute for Health and Care Excellence: Suspected cancer, recognition and referral. NICE guideline NG12