Symptoms guide

Shortness of Breath

Shortness of breath is the feeling of not being able to get enough air. It can be a normal response to hard exercise, but when it happens unexpectedly it may be a sign of a heart, lung, or other medical problem.

Last updated 3 sources

At a Glance

  • The medical term for shortness of breath is dyspnea.
  • Common causes involve the lungs and airways, the heart, or anxiety, but anemia and other conditions can also play a role.
  • Shortness of breath can come on suddenly (acute) or develop over weeks to months (chronic).
  • Sudden or severe trouble breathing, especially with chest pain, blue lips, or confusion, is generally treated as a medical emergency; in the US, people are advised to call 911.
  • A pulse oximeter measures blood oxygen level but does not show every cause of breathlessness.

What It Is

Shortness of breath describes an uncomfortable awareness of breathing or a sense of breathing hard. People may describe it as tightness in the chest, air hunger, being unable to take a deep breath, or feeling smothered.

Breathing depends on the airways, the lungs, the heart and blood vessels, the blood's ability to carry oxygen, and the muscles and nerves that control breathing. A problem in any of these can lead to breathlessness.

Shortness of breath during heavy exercise or at high altitude can be normal. Breathlessness that is new, unexplained, worsening, or out of proportion to activity is generally considered a reason for medical evaluation.

Common Terminology

Dyspnea
The medical term for shortness of breath or difficulty breathing.
Orthopnea
Shortness of breath that occurs when lying flat and eases when sitting up, often associated with heart failure.
Wheezing
A high-pitched whistling sound during breathing caused by narrowed airways.
Hypoxemia
A lower than normal level of oxygen in the blood.
Pulse oximetry
A painless test using a clip on the finger to estimate the oxygen level in the blood.
COPD
Chronic obstructive pulmonary disease, a long-term lung disease that makes it hard to breathe, often linked to smoking.

Common Causes and Associations

Shortness of breath is commonly associated with the following. This list is general education, not a way to identify the cause in any particular case.

  • Lung and airway conditions such as asthma, COPD, pneumonia, bronchitis, and lung scarring.
  • Heart conditions such as heart failure, heart attack, heart rhythm problems, and heart valve disease.
  • Blood clots in the lungs (pulmonary embolism) or a collapsed lung.
  • Anemia, where the blood carries less oxygen than normal.
  • Anxiety and panic attacks, which can cause rapid breathing and a sense of air hunger.
  • Other factors such as obesity, low physical fitness, severe allergic reactions, and high altitude.

Symptoms and Features

This is a general description of how this symptom is often described, not a diagnostic checklist.

  • A feeling of not getting enough air, chest tightness, or needing to breathe faster or harder.
  • It may occur only with activity, at rest, or when lying flat.
  • It may come with wheezing, coughing, chest pain, or a racing heart.
  • Swelling of the legs or ankles sometimes occurs alongside breathlessness in heart-related causes.
  • Bluish lips or fingertips, confusion, or difficulty speaking in full sentences can indicate a severe problem.

Tests and Evaluation

Clinicians generally use history, exam, and targeted tests to find the cause.

  • Pulse oximetry to estimate blood oxygen levels.
  • A chest X-ray or CT scan to look at the lungs and heart.
  • An electrocardiogram (ECG) and sometimes an echocardiogram to check the heart.
  • Lung function tests such as spirometry to measure how well air moves in and out of the lungs.
  • Blood tests, such as a complete blood count to check for anemia, or tests for heart strain or blood clots.

Treatment Overview

Treatment depends on the cause identified by a healthcare professional.

  • Asthma and COPD are commonly treated with inhaled medicines that open the airways or reduce inflammation.
  • Infections such as bacterial pneumonia may be treated with antibiotics.
  • Heart-related causes may be treated with medicines, procedures, and lifestyle changes.
  • Supplemental oxygen may be used when blood oxygen levels are low.
  • Pulmonary rehabilitation, breathing techniques, and regular physical activity can help some long-term conditions.

When Professional Care May Be Discussed

Health organizations generally describe these situations as reasons for urgent or prompt evaluation.

  • Sudden, severe shortness of breath, or breathlessness with chest pain, fainting, blue lips, or confusion, is generally treated as a medical emergency; in the US, people are advised to call 911.
  • Trouble breathing with swelling of the face, lips, or throat, or with hives, may signal a severe allergic reaction and is generally treated as an emergency.
  • Shortness of breath after surgery, long travel, or a period of immobility, especially with leg swelling, is commonly evaluated promptly.
  • Breathlessness that is getting worse over days or weeks, or that wakes a person at night, is commonly discussed with a healthcare professional.
  • Breathlessness with ordinary activities that previously caused no trouble is commonly evaluated.

Questions to Ask a Healthcare Professional

General questions people often find useful to bring to an appointment:

  • What are the most common causes of shortness of breath?
  • How do clinicians tell whether breathlessness comes from the heart or the lungs?
  • What does a pulse oximeter reading show, and what are its limits?
  • What are lung function tests and how are they done?
  • Which breathing warning signs are considered emergencies?
  • How can long-term conditions like asthma or COPD affect breathing over time?

Sources

This guide was written in plain language from the following authoritative references.

  1. Breathing Problems — MedlinePlus (U.S. National Library of Medicine)
  2. Shortness of breath — NHS (UK National Health Service)
  3. COPD — MedlinePlus (U.S. National Library of Medicine)

Last updated October 8, 2026. FreeDoc guides are general educational information and are not a substitute for care from a qualified professional.