What's Causing Your Shortness of Breath?

Causes of Shortness of Breath and When to Worry

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Young happy woman catching her breath after sport
What are the causes of shortness of breath, what tests may be done, and when should you worry?. Justin Case/Taxi/Getty Images

Shortness of breath is a common symptom, prompting people to make a visit to their doctor. This symptom may come on rapidly or come on so slowly that it's not recognized at first.

If you are experiencing shortness of breath, that does not mean you should necessarily be worried about lung cancer. There are many causes of shortness of breath. Yet, since "less common" causes of shortness of breath are often overlooked, it is important to make an appointment with your doctor to determine the cause.


We don’t have a clear definition of shortness of breath, but most people describe this symptom as a subjective sensation of difficulty with breathing. You may have a feeling of being unable to get enough air in or that it takes more effort to breathe than usual. Some people also describe a sensation of chest tightness. Shortness of breath can come on acutely in a matter of minutes or hours; or chronically over days, weeks, months or even years. 

Medical Terms

If you're reading about shortness of breath, you may be confused by all of the terms used to describe this symptom. A quick run down of some of these terms include:

  • Dyspnea refers to the sensation of shortness of breath
  • Tachypnea refers to rapid breathing with or without a feeling of being shortness of breath
  • Bradypnea means a slow rate of breathing

A normal respiratory rate in adults is considered to be between 12 and 18 breaths per minute while at risk.

Respiratory rate is considered by some to be the "forgotten" vital sign, and can sometimes give your doctor more information than either your blood pressure or your pulse with regard to the severity of illness.


In 85 percent of people, conditions related to the heart and lungs are responsible for shortness of breath.

Though most of us think of our lungs first if we feel short of breath, heart conditions need to be carefully considered. In fact, a study that looked at people who had shortness of breath as their only symptom of heart disease had a greater chance of dying than those who had typical chest pain.

Some of the more common causes include:

  • Asthma
  • COPD
  • Heart attacks
  • Pulmonary embolism, a blood clot that breaks off from another blood clot (deep vein thrombosis) in the legs or pelvis and travels to the lungs
  • Infections such as bronchitis and pneumonia
  • Congestive heart failure
  • Pneumothorax, a collapse of a lung

Other common causes include:

  • Smoking
  • Anemia
  • Thyroid conditions

Less common but important causes of shortness of breath may include:

  • Benign and malignant tumors, including lung cancer
  • Anxiety and panic attacks (learn more about shortness of breath and chest pain related to panic attacks)
  • Objects inhaled accidentally into the lungs
  • Heart valve problems
  • Acid reflux
  • Allergic reactions (anaphylaxis)
  • Neurological diseases such as multiple sclerosis
  • Other lung diseases such as sarcoidosis and bronchiectasis
  • Lack of regular exercise


It’s important to make an appointment to see your doctor if you develop shortness of breath, even if you think there is a clear reason to explain your symptoms.

Contact your doctor or call 911 immediately if you have chest pain, feel lightheaded or if your symptoms worsen rapidly.

When you visit your doctor, she will take a careful history and do a physical exam. Some of the questions she may ask include:

  • When did you first experience shortness of breath and how did it first begin?
  • Do your symptoms occur at rest or only with activity? If you only feel short of breath with activity, which activities seem to cause your symptoms?
  • Do you feel more winded when you are sitting up or lying down?
  • Do you have any other symptoms, such as chest pain, a cough, wheezing, fever, leg pain, unexplained weight loss or fatigue?
  • Do you have a personal of family history of any heart or lung problems?
  • Have you ever smoked? If so, for how long?
  • Have you traveled recently by car or by plane?


The tests your doctor will recommend will depend on your particular symptoms and physical findings, but may commonly include:

  • Pulse oximetry, a test performed by putting a clamp on your finger or earlobe to estimate the amount of oxygen in your blood
  • An electrocardiogram (EKG) to look for signs of a heart attack or irregular heart rhythms
  • A chest x-ray to look for infections or growths in your lungs (keep in mind that plain chest x-rays can miss lung cancer in the early stages)
  • Blood work to look for anemia and other causes
  • Pulmonary function tests to look for asthma or emphysema and other lung conditions

Other tests may include:

  • A CT scan of your chest
  • A stress test
  • An echocardiogram. This is an ultrasound of your heart to look for problems with your heart valves, how strong your heart is and if you have any damaged areas in your heart
  • A bronchoscopy

Learn more about how your doctor should evaluate shortness of breath (dyspnea).

Dyspnea and COPD

For those who have COPD, dyspnea is very common and the degree of dyspnea you have can give a lot of information as to the severity of your illness or an exacerbation. To do this, doctors often use what is called the modified medical research council dyspnea scale.


The treatment of your shortness of breath will depend on the cause, but the most important first step is to make sure you are getting enough air to supply your tissues with the oxygen they need. In emergency medicine, this is referred to as the ABC's with  A standing for airway, B standing for breathing, and C representing circulation.

When Is It an Emergency?

Sometimes it can be hard to know how serious your shortness of breath is, and that's when it's important to go with your intuition. In fact, sometimes the most severe shortness of breath can be something benign - like hyperventilation or a panic attack - but the mildest symptoms could be very serious.  If you are questioning calling 911 at all, go ahead and do so. If you didn't need the help, that's okay. But if you do, you don't want to wait too long.

Symptoms that suggest shortness of breath may be serious, however, include chest pain, a bluish tinge to your fingers and lips (cyanosis,) swelling or a feeling of fullness in your throat and lips, inability to talk due to difficult breathing, and a rapid increase in your symptoms. Don't try to drive yourself to urgent care or an emergency room, and it's better to call 911 than have a friend drive you.  Finally, don't be fooled if your symptoms seem to be suddenly improving. A decreased level of consciousness or the movement of a foreign body lodged in an airway can make symptoms appear to improve transiently.


Kasper, Dennis L.., Anthony S. Fauci, and Stephen L.. Hauser. Harrison's Principles of Internal Medicine. New York: Mc Graw Hill education, 2015. Print.

National Institute of Health. Medline Plus. Breathing Difficulty. Updated 06/22/15. https://medlineplus.gov/ency/article/003075.htm

Nishino, T. Dyspnoea: underlying mechanisms and treatment. British Journal of Anaesthesia. 2011. 106(4):463-74.