Shortness of breath (known as dyspnea) is often described as an intense tightening in the chest or feeling of suffocation. Depending on the cause, you may experience shortness of breath just once or have recurring episodes. Very strenuous exercise, extreme temperatures, obesity and high altitude all can cause shortness of breath in a healthy person. Shortness of breath may indicate a more serious medical problem. If you have unexplained shortness of breath, especially if it comes on suddenly and is severe, see your doctor as soon as possible.
If you experience severe shortness of breath that comes on suddenly and affects your ability to function, or if chest pain, fainting or nausea accompanies the shortness of breath, seek immediate medical attention. These may be signs of a heart attack or pulmonary embolism.