Symptoms of cystic fibrosis mainly involve the lungs, pancreas, sex organs, intestines, and sinuses and arise from abnormal mucus that is unusually thick and sticky. The mucus buildup in the lungs leads to repeated infections with coughing, production of thick sputum, shortness of breath, wheezing, nasal congestion, and a decreased tolerance for exercise or physical activity. Other symptoms of cystic fibrosis include fatty, foul-smelling stools, constipation, and poor growth in children. Malnutrition and vitamin deficiency can arise because pancreatic enzymes may not reach the intestine. Abdominal pain and swelling can occur. Cystic fibrosis also causes the sweat to be excessively salty and can cause infertility in men.