In general, acute cases of bronchitis do not cause any long-term damage to your lungs or health. Thus, while bronchitis should be taken seriously enough to seek medical attention for treatment, it should not cause you undue stress or worry. However, bronchitis can be serious when it becomes chronic or progresses into pneumonia. When bronchitis becomes chronic, it can damage the lungs and cause the tiny air sacs at the end of the bronchioles, known as the alveoli, to fill with fluid. Moreover, extra caution should also be taken for individuals in high-risk categories with bronchitis, such as the elderly, premature babies, those with a history of lung disease, and those who have cystic fibrosis. You should seek immediate medical attention for bronchitis if you have a high fever, a loss of appetite, or shortness of breath. If you have chest pain or significant difficulty breathing, call 911 or go to your nearest emergency room immediately.