The expectorant helps thin and loosen mucus in the lungs, making it easier to cough up the mucus.

Guaifenesin is an expectorant that helps thin and loosen mucus in the lungs, making it easier to cough up the mucus.

When inhaled by mouth, acetylcysteine is used to help thin and loosen mucus in the airways due to certain lung diseases (such as emphysema, bronchitis, cystic fibrosis, pneumonia).