Acetyl cysteine is used for the treatment of liver toxicity caused by paracetamol overdose. It is also used to thin and loosen the mucus in the airway due to certain lung diseases (bronchitis, pneumonia) and for the relief of dry eye syndromes associated with deficient tear secretion. It acts as mucolytic (loosen mucus in airways) when used in oral preparations while when used as injection it treats paracetamol overdose toxicity.