2. Persistent Coughing
Along with an increased level of salt in the sweat, the defective gene also causes people with cystic fibrosis to develop thick, sticky mucus. This mucus will build up in various parts of the body—including the lungs.
As it collects in the airways, it can make breathing more challenging. This can cause a person to cough persistently, often expelling some of the phlegm that’s responsible for the irritation.