CF affects mainly the lungs and the digestive system.
In the lungs, CF causes severe breathing problems. A build-up of thick mucus makes it difficult to clear bacteria and leads to cycles of infection and inflammation, which damage the delicate lung tissues. In the digestive tract, CF makes it extremely difficult to digest and absorb adequate nutrients from food. Thick mucus also blocks the ducts of the pancreas, preventing enzymes from reaching the intestines to digest food. They must also follow a demanding daily routine of physical therapy to keep the lungs free of congestion and infection.