causes for shortness of breath.
1 Heart disease or heart attack (in this case, shortness of breath may be accompanied by swelling of the feet/ankles). 2  Lung disease. 3  Emphysema. 4  Pneumonia (breathlessness often accompanied by high fever, cough and mucus). 5  Asthma or allergies. 6  Anemia (other symptoms characterized by fatigue and pale skin color).