Shortness of breath — the sensation that you cannot get enough air, that breathing requires more effort than it should, or that your chest feels tight when you breathe — is medically termed dyspnoea. It is one of the most common and distressing symptoms in medicine, listed among the top five reasons Americans visit emergency rooms. Distinguishing which of its many causes is responsible requires attention to the onset, severity, associated symptoms, and precipitating factors.
Heart Causes
Heart Failure
When the heart cannot pump blood efficiently, fluid backs up into the lungs (pulmonary oedema). The result is progressive dyspnoea — initially on exertion, then at rest, and eventually lying flat (orthopnoea, which forces sufferers to sleep propped on multiple pillows) and waking the person from sleep (paroxysmal nocturnal dyspnoea). Ankle swelling, fatigue, and rapid weight gain from fluid retention accompany cardiac dyspnoea. This requires urgent medical assessment.
Acute Coronary Syndrome
Shortness of breath is a common — and sometimes the only — symptom of heart attack, particularly in women, elderly patients, and diabetics who may not experience typical chest pain. New dyspnoea with exertion, sweating, or chest pressure is a cardiac emergency.
Lung Causes
Asthma
Airway inflammation and bronchospasm restrict airflow and produce dyspnoea, chest tightness, wheezing, and cough — typically episodic and triggered by allergens, exercise, cold air, or respiratory infections. Well-controlled asthma should produce minimal symptoms; frequent dyspnoea despite treatment suggests inadequate control or an alternative diagnosis.
COPD (Chronic Obstructive Pulmonary Disease)
The leading cause of progressive exertional dyspnoea in smokers over 40. Emphysema and chronic bronchitis destroy alveolar tissue and obstruct airflow, reducing oxygen transfer. The hallmark is dyspnoea with exertion that gradually worsens over years, combined with chronic productive cough. Spirometry confirms the diagnosis; smoking cessation is the only intervention shown to slow progression.
Pulmonary Embolism
Sudden onset dyspnoea — particularly with pleuritic chest pain, rapid heart rate, or coughing blood — without an obvious cause should immediately raise concern for pulmonary embolism. This is a medical emergency. Risk is elevated after surgery, prolonged immobility, cancer, or oral contraceptive use.
Pneumonia
Infection of the lung parenchyma causes dyspnoea, cough, fever, and pleuritic chest pain. Severity ranges from mild (manageable at home) to life-threatening respiratory failure requiring intensive care.
Other Causes
- Anaemia: Reduced oxygen-carrying capacity produces dyspnoea on exertion; often accompanies fatigue and pallor.
- Deconditioning: Poor cardiovascular fitness from a sedentary lifestyle causes dyspnoea with activities that should be tolerable. Progressive aerobic exercise is the treatment.
- Anxiety and panic attacks: Hyperventilation and dysfunctional breathing patterns produce dyspnoea, chest tightness, and tingling that can be difficult to distinguish from cardiac or pulmonary causes.
- Obesity: Increased respiratory demand and diaphragmatic restriction cause exertional dyspnoea; weight loss typically produces substantial improvement.
- COVID-19 and Long COVID: Both acute and post-acute dyspnoea are well-recognised complications.
When to Call 911
Seek emergency care for: sudden severe dyspnoea, dyspnoea at rest, dyspnoea with chest pain or pressure, one-sided facial or limb weakness, bluish lips or fingernails (cyanosis), or confusion. Any new dyspnoea in someone with a history of heart or lung disease warrants urgent evaluation.
Sources
- Parshall MB, et al. An Official ATS Statement: Update on the Mechanisms, Assessment, and Management of Dyspnea. Am J Respir Crit Care Med. 2012.
- Global Initiative for Asthma. GINA Report 2023.
- Mayo Clinic. Shortness of breath — Causes. 2023.