Chronic obstructive pulmonary disease (COPD) causes you to cough up mucus and makes it difficult to breathe. COPD is a combination of two different chronic lung diseases—chronic bronchitis and emphysema. Bronchitis is an inflammation in the airways (bronchi). Emphysema causes damage to the air sacs (alveoli) in the lungs. There is no cure for COPD, but COPD treatment and management can ease breathing.