Folcisteine is primarily used in the pharmaceutical industry as a mucolytic agent. It helps break down and thin mucus in the respiratory tract, making it easier to clear from the airways. This makes it particularly beneficial in treating conditions like chronic obstructive pulmonary disease (COPD), bronchitis, and cystic fibrosis, where excessive mucus production can obstruct breathing. Additionally, it is sometimes used to support lung function in patients recovering from respiratory infections or surgeries. Its antioxidant properties also contribute to protecting lung tissue from damage caused by inflammation or oxidative stress.