What causes shortness of breath?

Shortness of breath (dyspnea) is a symptom that can arise from many different causes, some of which, but not all, are associated with serious disease processes.

Dyspnea is most often caused by diseases of the lungs or heart – both of these organs are important to the delivery of oxygen to the tissues of the body, and removal of carbon dioxide. Dyspnea often signals a problem in oxygen delivery or carbon dioxide removal. Lung diseases that cause dyspnea include asthma, emphysema (chronic obstructive lung disease), pulmonary fibrosis, lung cancer, collapsed lung (pneumothorax), interstitial lung disease, etc.

Heart and blood vessel diseases that cause dyspnea include heart attack (especially in women), congestive heart failure, pulmonary hypertension, etc.  Other diseases that sometimes cause dyspnea include metabolic disorders of muscles, neuromuscular diseases, etc. In many cases a pulmonary physician or cardiologist can find the cause of dyspnea, but in difficult cases a special dyspnea clinic can help. It is not uncommon for us to determine that your level of fitness may have deteriorated over the years because of lack of exercise, and this can be the reason for your symptoms.

In addition, some people experience dyspnea without any identifiable physical cause; these cases are often associated with anxiety disorders. A ‘vicious circle’ can develop in patients with dyspnea.  Because exercise is uncomfortable for these people, they often stop exercising.  This leads to them gaining weight and becoming more and more out of shape, which in turn leads to even more problems with dyspnea.  Even when the underlying disease process cannot be reversed, these patients often find significant improvement when they are guided through an exercise program to get back in shape. See ‘pulmonary rehabilitation.’

Because dyspnea often indicates development of serious disease, you should report it to your doctor and seek the cause.  Perhaps you are short of breath only because you are ‘out of shape’; your doctor can help you assess this, and can suggest an exercise program suitable for your health and age. However, if there is any doubt at all in your mind, you should get professional help in making this judgment because dyspnea is a warning, and taking action can often prevent more serious problems.