Merck Manual

Please confirm that you are not located inside the Russian Federation

Some Causes and Features of Shortness of Breath

Some Causes and Features of Shortness of Breath

Cause

Common Features*

Tests†

Acute (develops within minutes or hours)

Anxiety disorder—hyperventilation

Shortness of breath related to a specific situation, often accompanied by agitation and tingling or numbness in the fingers and/or around the mouth

Normal results on the heart and lung examination

A doctor's examination

Asthma

Wheezing that starts spontaneously or after exposure to specific stimuli (such as pollen or another allergen, an upper respiratory infection, cold air, or exercise)

Usually a history of asthma

A doctor's examination

Sometimes one or more of the following tests:

  • Tests to evaluate how well the lungs are functioning (pulmonary function testing), or measurement of peak air flow (how fast air can be exhaled)

  • Measurement of lung function before and after exercise or administration of methacholine (a drug that narrows airways)

  • Sometimes use of bronchodilators (drugs that widen airways) to see whether symptoms go away

A foreign object that has been inhaled

A cough or high-pitched wheezing that starts suddenly in people (typically infants or young children) without any symptoms of an upper respiratory infection or other illness

A chest x-ray or CT

Sometimes bronchoscopy

A heart attack or acute myocardial ischemia (inadequate blood flow and oxygen supply to the heart)

Deep chest pressure that may or may not radiate to the arm or jaw, particularly in people with risk factors for coronary artery disease

Electrocardiography

Blood tests to measure substances called cardiac markers, which are released into the blood when the heart is damaged

Sometimes cardiac catheterization

Often swelling (edema) of the legs

Shortness of breath that worsens while lying flat (orthopnea) or that appears 1–2 hours after falling asleep (paroxysmal nocturnal dyspnea)

Sounds suggesting fluid in the lungs, heard through a stethoscope

Frothy, pink sputum, sometimes with blood streaks

A chest x-ray

Sometimes a blood test to measure brain natriuretic peptide (BNP), a substance that is produced when the heart. is strained

Sometimes echocardiography

Pneumothorax (a collapsed lung)

Sharp chest pain and rapid breathing that start suddenly

May follow an injury or occur spontaneously, especially in tall, thin people and in people with COPD

A chest x-ray

Pulmonary embolism (sudden blockage of an artery in a lung, usually by a blood clot)

Sudden appearance of sharp chest pain that usually worsens when inhaling

A rapid heart rate and a rapid breathing rate

Often risk factors for pulmonary embolism, such as cancer, immobility (as results from being bedbound), blood clots in the legs, pregnancy, use of birth control pills (oral contraceptives) or other drugs that contain estrogen, recent surgery or hospitalization, or a family history of the disorder

Specialized lung imaging tests, such as CT angiography, ventilation/perfusion (V/Q) scanning, or pulmonary arteriography.

Subacute (develops over hours or days)

Angina or coronary artery disease

Deep chest pressure that may or may not radiate to the arm or jaw, often triggered by physical exertion

Often in people with risk factors for coronary artery disease

Electrocardiography

Stress testing

Sometimes cardiac catheterization

Often a cough that may or may not produce sputum (productive or nonproductive)

Wheezing and breathing through pursed lips

In people who already have COPD

A doctor's examination

Sometimes a chest x-ray

Fever, a feeling of illness, and a productive cough

Sudden appearance of sharp chest pain when taking deep breaths

Certain abnormal breath sounds, heard through a stethoscope

A chest x-ray

Chronic (present for many weeks to years)

Shortness of breath during exertion, progressing to shortness of breath at rest

Normal lung examination results and oxygen levels in the blood

A complete blood cell count

Abnormal lung sounds called crackles, heard through a stethoscope

High-resolution CT of the chest

Obstructive lung disease

A history of extensive smoking, a barrel-shaped chest, and difficulty moving air in and out of the lungs

Usually in people who already have COPD

A chest x-ray

Pulmonary function testing (after the episode of shortness of breath subsides)

Physical deconditioning

Shortness of breath only during exertion

In older people with a sedentary lifestyle

A doctor's examination

Pleural effusion (fluid in the chest cavity)

Sometimes a history of cancer, heart failure, rheumatoid arthritis, systemic lupus erythematosus (lupus), or acute pneumonia

A chest x-ray

Often CT of the chest

Gradually worsening shortness of breath and fatigability, sometimes with cough

Sometimes an abnormal heart examination

Sometimes leg swelling

Echocardiography

Right heart catheterization

Restrictive lung disease

Gradually worsening shortness of breath in people known to have been exposed to inhaled irritants at work (occupational exposure) or to have a disorder of the nervous system

A chest x-ray

Pulmonary function testing (after the episode of shortness of breath subsides)

Stable angina or coronary artery disease

Deep chest pressure that may or may not radiate to the arm or jaw, often triggered by physical exertion

Often in people with risk factors for coronary artery disease

Electrocardiography

Stress testing

Sometimes cardiac catheterization

* Features include symptoms and results of the doctor's examination. Features mentioned are typical but not always present.

† Doctors almost always measure the oxygen level in the blood and, unless symptoms are clearly a mild flare-up of an already diagnosed chronic disorder, take a chest x-ray.

‡ Asthma can also be a subacute cause of dyspnea.

§ Heart failure can also be chronic cause of dyspnea.

COPD = chronic obstructive pulmonary disease; CT = computed tomography.