Causes

Most cases of shortness of breath are due to heart or lung conditions. Your heart and lungs are involved in transporting oxygen to your tissues and removing carbon dioxide, and problems with either of these processes affect your breathing.

Shortness of breath that comes on suddenly (called acute) has a limited number of causes, including:

• Anaphylaxis (a severe allergic reaction)
• Asthma
• Carbon monoxide poisoning
• Cardiac tamponade (excess fluid around the heart)
• COPD (chronic obstructive pulmonary disease) exacerbation — worsening of symptoms
• Coronavirus disease 2019 (COVID-19)
• Heart attack
• Heart arrhythmia (heart rhythm problems)
• Heart failure
• Pneumonia (and other pulmonary infections)
• Pneumothorax (collapsed lung)
• Pulmonary embolism (blood clot in an artery in the lung)
• Sudden blood loss
• Upper airway obstruction (blockage in the breathing passage)

In the case of shortness of breath that has lasted for weeks or longer (called chronic), the condition is most often due to:

• Asthma
• COPD (chronic obstructive pulmonary disease) exacerbation — worsening of symptoms
• Deconditioning
• Heart dysfunction
• Interstitial lung disease
• Obesity
• Pleural effusion (accumulation of fluid around the lungs)

A number of other health conditions also can make it hard to get enough air. These include:

Lung problems

• Croup (especially in young children)
• Lung cancer
• Pleurisy (inflammation of the membrane surrounding the lungs)
• Pulmonary edema (excess fluid in the lungs)
• Pulmonary fibrosis (scarred and damaged lungs)
• Pulmonary hypertension
• Sarcoidosis (collections of inflammatory cells in the body)
• Tuberculosis

Heart problems

• Cardiomyopathy (problem with the heart muscle)
• Heart failure
• Pericarditis (inflammation of the tissue around the heart)

Other problems

• Anemia
• Anxiety disorders
• Broken ribs
• Choking: First aid
• Epiglottitis (swelling of the "lid" of your windpipe)
• Foreign object inhaled: First aid
• Guillain-Barre syndrome
• Kyphoscoliosis (a chest wall deformity)
• Myasthenia gravis (a condition causing muscle weakness)