Cystic fibrosis is a life-threatening chronic condition that causes mucus to build up and clog some of the organs in the body, particularly in the lungs and pancreas. When mucus clogs the lungs, it can make breathing very difficult. The thick mucus also causes bacteria (or germs) to get stuck in the airways, which causes inflammation (or swelling) and infections that leads to lung damage. Mucus also can block the digestive tract and pancreas. The mucus stops digestive enzymes from getting to the intestines. The body needs these enzymes to break down food, which provides important nutrients to help us grow and stay healthy. People with cystic fibrosis often need to replace these enzymes with capsules they take with their meals and snacks to help digest the food and get the proper nutrition.