Acetylcysteine is used to liquify and loosen the mucus in the airways. The mucus will become easier to cough up. This reduces the urge to cough. Acetylcysteine is used for people with excessive mucus during a cold or influenza, but also for certain lung conditions such as cystic fibrosis, emphysema, bronchitis, tuberculosis. Always read the leaflet before the use of medication.