Symptomatic diseases

Lung and sinus disease
Lung disease results from clogging of airways due to inflammation. Inflammation and infection cause injury to the lungs and structural changes that lead to a variety of symptoms. In the early stages, incessant coughing, copious phlegm production, and decreased ability to exercise are common. Many of these symptoms occur when bacteria that normally inhabit the thick mucus grow out of control and cause pneumonia. In later stages of CF, changes in the architecture of the lung further exacerbate chronic difficulties in breathing.

Aspergillus fumigatus - A common fungus which can lead to worsening lung disease in people with CF
Other symptoms include coughing up blood (hemoptysis), changes in the major airways in the lungs (bronchiectasis), high blood pressure in the lung (pulmonary hypertension), heart failure, difficulties getting enough oxygen to the body (hypoxia), and respiratory failure requiring support with breathing masks such as bilevel positive airway pressure machines or ventilators In addition to typical bacterial infections, people with CF more commonly develop other types of lung disease. Among these is allergic bronchopulmonary aspergillosis, in which the body's response to the common fungus Aspergillus fumigatus causes worsening of breathing problems. Another is infection with mycobacterium avium complex (MAC), a group of bacteria related to tuberculosis, which can cause further lung damage and does not respond to common antibiotics.
Mucus in the paranasal sinuses is equally thick and may also cause blockage of the sinus passages, leading to infection. This may cause facial pain, fever, nasal drainage, and headaches. Individuals with CF may develop overgrowth of the nasal tissue (nasal polyps) due to inflammation from chronic sinus infections. These polyps can block the nasal passages and increase breathing difficulties.