Breathlessness may develop during exertion, when lying flat, at night or at rest. The pattern, speed of change and associated symptoms are more informative than the symptom alone.
Why the Symptom Pattern Matters
- Progressive exertional breathlessness can occur with heart failure, valve disease, anaemia, lung disease or loss of conditioning.
- Difficulty lying flat or waking breathless may suggest congestion but also occurs in other conditions.
- Sudden breathlessness raises concern for pulmonary embolism, pneumothorax, arrhythmia or acute pulmonary oedema.
- Wheeze, cough, fever, chest pain and leg swelling help direct assessment.
Possible Causes
This list explains possibilities; the symptom alone cannot establish a diagnosis.
- Heart failure, valve disease or cardiomyopathy
- Arrhythmia or coronary ischaemia
- Pulmonary embolism, asthma, COPD or infection
- Anaemia and thyroid or metabolic disease
- Obesity, deconditioning and anxiety
What the Clinician Will Assess
- Onset, exertion threshold and positional or night-time symptoms
- Weight gain, swelling, cough, wheeze, fever or chest pain
- Oxygen level, respiratory rate and heart-lung examination
- Previous heart, lung, clotting or blood disease
Which Tests May Be Considered?
Not every test is required for every person. Selection depends on examination findings and clinical probability.
- ECG, chest imaging and blood tests
- Natriuretic peptides and echocardiography when heart failure is possible
- D-dimer and CT pathway when pulmonary embolism is clinically suspected
- Lung function or exercise testing in selected stable cases
What to Record Before the Appointment
- Walking distance or stair threshold
- Number of pillows and night waking
- Weight, swelling, pulse and blood pressure
- Oxygen readings only from a suitable device and within a clinical plan
When to Call Emergency Services
Do not wait for an online reply
- Severe breathlessness at rest or inability to speak normally
- Blue lips, confusion or collapse
- Breathlessness with chest pain, coughing blood or one-sided leg swelling
- Pink frothy sputum or rapidly worsening symptoms
Frequently Asked Questions
Is breathlessness always from the heart?
No. Lung, blood, metabolic and conditioning causes are common.
Can normal oxygen exclude heart failure?
No. Oxygen may be normal in stable or early heart failure.
Should I increase a diuretic myself?
Only if your heart-failure team has provided a specific written adjustment plan.
Medical information note
This page provides general information and does not replace examination, diagnosis or an individual treatment plan.