Shortness of Breath

Shortness of Breath: A Complete Patient Guide

In short

Breathlessness that is new, worsening, out of proportion to effort or present at rest needs assessment. Heart and lung conditions are the commonest causes, and an ECG, blood tests, a chest X-ray and an echocardiogram help tell them apart. Call 999 if it is sudden and severe, or comes with chest pain, blue lips or confusion.

Shortness of breath overview

Shortness of breath (breathlessness or dyspnoea) is the uncomfortable awareness of breathing: feeling you cannot get enough air, or that breathing takes effort. Some breathlessness is normal with vigorous exercise, but breathlessness that is new, worsening, out of proportion to effort, or present at rest needs a proper explanation. Many people describe it as feeling short of breath, tight in the chest or unable to take a deep breath.

The two most common groups of causes are the heart and the lungs, and they can coexist. Cardiac causes include heart failure, coronary artery disease, heart valve disease, heart rhythm problems such as atrial fibrillation, cardiomyopathy, pericardial disease and pulmonary hypertension. Lung causes include asthma, COPD, interstitial lung disease, infection and pulmonary embolism. Anaemia, obesity, thyroid disease, deconditioning and anxiety are also common contributors.

Because breathlessness is such a common and non-specific symptom, assessment focuses on a careful history and a small number of targeted tests, usually an ECG, blood tests including a natriuretic peptide (NT-proBNP), a chest X-ray, lung function tests and an echocardiogram. Identifying a heart cause matters because many are very treatable.

Shortness of breath symptoms and signs

The pattern of breathlessness gives clues to its cause.

Heart-related patterns

Breathlessness on exertion that has gradually worsened, reducing how far you can walk or climb stairs
Breathlessness lying flat (orthopnoea), needing extra pillows, or waking at night gasping (paroxysmal nocturnal dyspnoea)
Associated ankle swelling, tiredness, weight gain, chest tightness or palpitations

Lung-related patterns

Wheeze, cough with or without phlegm, chest tightness and variable symptoms
A history of smoking, asthma, COPD or occupational exposures
Fever, productive cough or pleuritic chest pain suggesting infection

Other clues

Pale, tired and breathless with minimal effort: anaemia
Sudden breathlessness with pleuritic chest pain or a swollen calf: pulmonary embolism
Breathlessness with a feeling of panic, tingling or rapid breathing: anxiety or hyperventilation, once other causes have been excluded

Is it my heart, my lungs or anxiety?

Heart, lung and anxiety-related breathlessness overlap and can coexist, so no single feature settles the cause. The pattern of symptoms gives useful clues, and simple tests then confirm them.

Pointers towards the heart

Breathlessness on exertion that has gradually worsened over weeks or months
Breathlessness lying flat, needing extra pillows, or waking at night gasping for air
Swollen ankles, weight gain, unusual tiredness or a reduced appetite
Known heart disease, high blood pressure, diabetes, a previous heart attack or a heart murmur

A systematic review of emergency department studies in JAMA found that waking at night breathless made heart failure about 2.6 times more likely, and a past history of heart failure about 5.8 times more likely. Having no breathlessness on exertion made heart failure less likely. A low BNP blood level was the most useful single test for ruling heart failure out.

Pointers towards the lungs

Wheeze, cough or phlegm
A history of smoking, asthma or COPD
Symptoms that vary with cold air, allergies or chest infections

Pointers towards anxiety or over-breathing

Breathlessness that comes at rest or in stressful situations, out of proportion to effort
Frequent sighing or yawning, or a feeling of being unable to take a satisfying deep breath
Tingling in the fingers or around the mouth, with a feeling of panic
Normal heart and lung tests

Anxiety is a real cause of breathlessness, but it is only diagnosed once heart and lung causes have been considered, because people with heart disease can be anxious too.

How doctors tell the difference

An ECG, an NT-proBNP blood test and an echocardiogram usually separate a heart cause from other causes. NICE advises that an NT-proBNP level below 400 ng/L makes heart failure unlikely. Lung tests and a chest X-ray look at the lungs.

Shortness of breath when lying down, walking or coming and going

The timing and trigger of breathlessness help to narrow the cause. These are the three patterns patients most often ask about.

Shortness of breath when lying down

Breathlessness on lying flat is called orthopnoea. In heart failure, lying down moves fluid from the legs into the chest and raises the pressure in the lung veins, so breathing is easier when you sit up. Needing extra pillows, sleeping in a chair, or waking 1 to 2 hours after going to bed gasping for air (paroxysmal nocturnal dyspnoea) are typical.

Other causes include obesity, asthma and COPD, acid reflux, sleep apnoea, fluid around the lung and anxiety. Because a heart cause is treatable, new breathlessness lying flat should be assessed, and call 999 if it is severe or comes with chest pain.

Shortness of breath when walking

Breathlessness on exertion that gradually reduces how far you can walk, or how many stairs you can climb, is the commonest heart-related pattern. Heart causes include heart failure, coronary artery disease (breathlessness can be the only symptom of angina), aortic stenosis, mitral valve disease, atrial fibrillation with a fast heart rate, cardiomyopathy and pulmonary hypertension. Lung disease, anaemia, obesity and poor fitness are also common.

It helps to note how far or how many stairs it takes, and how this compares with six months ago. An echocardiogram and, if needed, a stress echo test the heart under effort.

Shortness of breath that comes and goes

Episodes that come and go suggest intermittent causes such as paroxysmal atrial fibrillation or SVT (often with palpitations), angina, asthma, anxiety or panic, and recurrent fluid build-up. A heart rhythm recorder worn for days to weeks (cardiac monitoring) can catch an episode, and a symptom diary of when it happens and what you were doing is very helpful.

Causes of shortness of breath

Breathlessness can have more than one cause at once, which is why a thorough assessment helps.

Heart causes

Heart failure (weak or stiff heart)
Coronary artery disease and angina (breathlessness may be the only symptom)
Valve disease, such as aortic stenosis and mitral regurgitation
Atrial fibrillation and other rhythm disturbances, cardiomyopathies and pericardial disease
Pulmonary hypertension and congenital heart disease

Lung and blood vessel causes

Asthma, COPD, bronchiectasis and interstitial lung disease
Pneumonia, pleural effusion and pneumothorax
Pulmonary embolism (a clot in the lungs)

Other causes

Anaemia, an overactive or underactive thyroid, and kidney disease
Obesity and deconditioning
Anxiety and panic, and obesity hypoventilation
Medicines (for example, some chemotherapy and amiodarone)

How shortness of breath is diagnosed

The aim is to establish whether the heart, lungs or something else is responsible.

1. History and examination

Your cardiologist will explore how far you can walk, whether you are breathless lying flat, swelling, chest pain, palpitations, smoking and medicines. Pulse, blood pressure, oxygen level, heart sounds, lungs and swelling are examined.

2. ECG

An ECG checks for rhythm disturbance, previous heart attack and strain. A normal ECG makes heart failure with a weak heart unlikely.

3. Blood tests

A natriuretic peptide (NT-proBNP) blood test is used to assess the likelihood of heart failure. NICE advises that a level above 2,000 ng/L needs specialist assessment within 2 weeks, and a level of 400 to 2,000 ng/L within 6 weeks. Blood count, kidney, thyroid and liver function and blood sugar are also checked.

4. Echocardiogram

An echocardiogram shows how well the heart pumps and relaxes, the valves and the pressures in the lungs, and is the key test for a heart cause.

5. Lung tests and further heart tests

A chest X-ray and lung function tests (spirometry) are used to assess the lungs. If a cardiac cause is suspected, further tests may include stress echo, exercise ECG, CT coronary angiography, cardiac MRI or bubble echo.

Shortness of breath treatment options

Treatment depends entirely on the cause, which is why the investigations matter.

If it is the heart

Heart failure: foundational medicines, diuretics for fluid and treatment of the cause
Coronary disease: antiplatelet, statin, anti-anginal medicines, and stents or bypass in selected people
Valve disease: monitoring, and valve repair or replacement when indicated
Atrial fibrillation: stroke prevention, rate or rhythm control, cardioversion or ablation

If it is the lungs

Inhalers and other medicines for asthma and COPD, antibiotics for infection, anticoagulants for pulmonary embolism, and respiratory specialist care for interstitial lung disease.

If it is something else

Iron or other treatment for anaemia, thyroid treatment, weight loss and graded exercise for obesity and deconditioning, and psychological therapies for anxiety-related breathlessness.

General measures

Stop smoking, get vaccinated against influenza, COVID-19 and pneumococcus, and stay as active as you can
Pulmonary or cardiac rehabilitation helps both heart and lung causes

Living with shortness of breath

Keep active. Regular, gently increasing activity improves breathlessness in both heart and lung conditions.
Pace yourself. Break tasks into steps and rest between them.
Breathing techniques such as pursed-lip breathing and a slow, relaxed pattern can help during an episode.
Weigh yourself daily if you have heart failure, and report a gain of more than about 2 kg in 3 days.
Sleep propped up if breathless when lying flat, and mention this to your doctor.
Stop smoking, and avoid smoky environments.
Take medicines as prescribed, and keep a record of your symptoms.
Support is available from the British Heart Foundation, Asthma + Lung UK and the NHS.

Shortness of breath prognosis and outlook

The outlook depends entirely on the cause. Many causes of breathlessness are highly treatable, and treatment usually improves symptoms considerably.
Heart causes such as heart failure, valve disease and atrial fibrillation respond well to modern treatment, particularly when diagnosed early.
Breathlessness caused by deconditioning, anaemia or anxiety often improves with the right approach.
Persistent unexplained breathlessness deserves repeated assessment, because multiple causes often coexist.
Early investigation, rather than waiting, gives the best chance of effective treatment.

When to see a doctor about shortness of breath

Do not put persistent breathlessness down to age or lack of fitness without having it checked.

Arrange an assessment if you have:

Breathlessness that is new, worsening, or that limits what you can do
Breathlessness lying flat or waking you at night
Ankle swelling, weight gain, palpitations or chest tightness with breathlessness
A heart murmur, a history of heart disease, high blood pressure, diabetes or a family history of cardiomyopathy
A persistent cough or wheeze that has not been explained

If you are unsure

A cardiology assessment with an ECG and echocardiogram can quickly show whether the heart is responsible, and often provides reassurance.

Shortness of breath red flags

These features suggest a more serious cause and call for urgent assessment.

Red flags

Rapidly worsening breathlessness over hours to days
Breathlessness at rest or on minimal effort
Chest pain, fainting or palpitations with the breathlessness
Swollen legs with a painful or red calf (possible clot)
Coughing blood or pink frothy phlegm
Blue or grey lips or face

What to do

Seek urgent assessment the same day. If symptoms are severe, call 999.

When to call 999 about shortness of breath

Breathlessness with the following needs emergency help.

Call 999 immediately if you have:

Severe breathlessness at rest, or you cannot speak in full sentences
Chest pain or pressure, especially with sweating or pain spreading to the arm or jaw
Fainting or collapse
Blue lips, confusion or drowsiness
Coughing up pink frothy phlegm or blood
Sudden breathlessness with a swollen, painful leg or after long travel or surgery

While waiting

Sit upright, loosen tight clothing and stay as calm as you can. Do not drive yourself.

Shortness of breath key facts

Breathlessness is common, and the two main groups of causes are the heart and the lungs.
Heart causes include heart failure, coronary disease, valve disease and atrial fibrillation.
Breathlessness lying flat, waking at night or with swollen ankles points to a heart cause.
The key tests are an ECG, NT-proBNP blood test and echocardiogram, with lung tests.
NICE advises specialist assessment within 2 weeks if NT-proBNP is above 2,000 ng/L.
Anaemia, thyroid disease, obesity, deconditioning and anxiety are also common.
Treatment depends on the cause, and most are treatable.
Severe breathlessness, chest pain or fainting need 999.

Guidelines and sources

This page follows current UK and European guidance:

NICE NG106: Chronic heart failure in adults: diagnosis and management.
McDonagh TA et al. 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. European Heart Journal 2021;42:3599-3726.

Shortness of breath questions and answers

These are the questions patients most often ask about shortness of breath.

What causes shortness of breath?

Most commonly heart or lung disease. Heart causes include heart failure, coronary disease, valve disease and atrial fibrillation. Anaemia, obesity, deconditioning and anxiety are also common.

How do I know if my shortness of breath is from the heart or lungs?

Breathlessness lying flat, waking at night, ankle swelling and tiredness suggest the heart, whereas wheeze, cough and a smoking history suggest the lungs. Tests such as an ECG, NT-proBNP and echocardiogram usually settle it.

When should I worry about shortness of breath?

If it is new, worsening, present at rest, or comes with chest pain, fainting, palpitations, leg swelling or blue lips. Call 999 for severe breathlessness.

What heart conditions cause shortness of breath?

Heart failure, coronary artery disease, heart valve disease, atrial fibrillation and other arrhythmias, cardiomyopathy, pericardial disease and pulmonary hypertension.

Can heart failure cause shortness of breath?

Yes, it is one of its main symptoms, usually with tiredness and swollen ankles. See our heart failure guide for more.

What tests are done for shortness of breath?

An ECG, blood tests including NT-proBNP, a chest X-ray, lung function tests and an echocardiogram. Further tests depend on what is found.

Can anxiety cause shortness of breath?

Yes, but it is a diagnosis made only after heart and lung causes have been considered. Anxiety and heart disease can coexist.

Is shortness of breath on exertion normal as you age?

Some reduction in stamina is normal, but a clear decline, or breathlessness on mild effort, is not just age and should be assessed.

Can I have a private assessment for breathlessness?

Yes. A telephone, video or face-to-face consultation in Peterborough or Corby can assess your breathlessness, with ECG reporting, echocardiography and other tests arranged as needed.

How do I know if my breathlessness is heart-related?

Breathlessness that comes on with exertion and has gradually worsened, breathlessness lying flat or waking you at night, and swollen ankles or unusual tiredness point towards the heart. An ECG, an NT-proBNP blood test and an echocardiogram usually settle the question.

What are the early warning signs of heart failure?

The early signs are breathlessness on exertion or lying flat, swollen ankles, unusual tiredness and weight gain over a few days. They are often put down to age or poor fitness, so it is worth having them checked.

Can shortness of breath come and go?

Yes. Episodes that come and go can be caused by an irregular heart rhythm, angina, asthma, anxiety or fluid build-up. A heart rhythm monitor and a symptom diary help to find the cause.

Questions to ask your cardiologist about shortness of breath

Is my breathlessness due to my heart, lungs or something else?
Which tests do I need, and what will they show?
Do I have heart failure, valve disease or a rhythm problem?
What treatment will help, and how quickly?
How much exercise is safe for me?
What symptoms should make me seek urgent help?
When should I be reviewed again?
Could anaemia, lung disease, a blood clot or a thyroid problem be contributing?
Would losing weight, stopping smoking or other lifestyle changes help?
Which symptoms should I track at home, such as weight, swelling or oxygen levels?

Shortness of breath diagrams and visual aids

The heart sits in the chest between the lungs, so heart and lung problems can both cause breathlessness.

Image: BruceBlaus / Blausen.com staff, Blausen 0458 Heart ThoracicCavity, Wikimedia Commons. Licensed under CC BY 3.0.

Where breathlessness can come from

Breathlessness has many causes. Heart and lung conditions are the most common, but anaemia, thyroid disease, kidney disease and low fitness can also be responsible, and more than one cause can be present together.

Heart or lungs? Clues from your symptoms

Certain features of the story point towards the heart and others towards the lungs. These are clues only. The history, examination and tests decide the cause.

How shortness of breath is investigated

Most people need a short series of tests. A normal NT-proBNP blood test makes heart failure unlikely, and an echocardiogram then shows how the heart pumps and whether a valve problem is present.

Related heart conditions and tests

Further reading from Dr Salam Salloum, Consultant Cardiologist.

If you have shortness of breath, reduced stamina or ankle swelling, you may benefit from a telephone consultation or video consultation to discuss your symptoms in detail, or a face-to-face consultation in Peterborough or Corby for a more comprehensive assessment. Severe breathlessness needs a 999 call.

Investigations such as echocardiography, ECG reporting and stress echo may be recommended.

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Medically reviewed by Dr Salam Salloum, Consultant Cardiologist. Last reviewed: 22 October 2026. This page is for general information and does not replace personal medical advice.