Shortness of breath may be due to strenuous exercise, asthma, chronic obstructive pulmonary disease, heart failure, angina pectoris, hypoglycemia and other causes. 1. Strenuous exercise: after strenuous exercise, the body’s tissue cell oxygen consumption increases dramatically, so it will physiologically increase the respiratory rate to ensure the supply of oxygen, thus shortness of breath. 2. Asthma: patients with innate airway hyperreactivity induce an allergic reaction after contact with allergens such as dust, hair, seafood, etc. The bronchial tubes constrict and spasm, resulting in shortness of breath. 3. Chronic obstructive pulmonary disease (COPD): chronic inflammatory reaction in bronchial tubes and fine bronchial tubes, leading to irreversible narrowing and obstruction of airways, and shortness of breath due to insufficient pulmonary ventilation. 4. Heart failure: after the heart systolic and diastolic dysfunction, the pumping function is reduced, the pulmonary circulation is stagnant, resulting in pulmonary dysfunction, so shortness of breath. 5. Angina pectoris: atherosclerotic narrowing of the coronary arteries, resulting in a decrease in the blood supply to the heart, ischemia and hypoxia of cardiac myocytes, stimulating increased respiration and shortness of breath. 6. Hypoglycemia: When blood sugar is too low, the tissue cells lack energy supply, which reflexively excites the sympathetic nerves, leading to panic and shortness of breath. Shortness of breath may be related to a variety of factors, it is recommended to consult a doctor for a clear diagnosis.