This is a prospective randomized clinical trial about the efficacy of heparin nebulization on lung injury score in inhalation burn injury in Mothary burn hospital. This study would consist of 170 burn patients with documented inhalation injury in 2 arms (control group and study group). Allocation ratio is1:1. Masking was not possible. The patients' primary outcome will be assessed for Lung Injury Scale and the patients' secondary outcome will be assessed for mortality, Coagulation tests (PT, PTT), ICU and hospital stay and duration of mechanical ventilation support. Duration of this study is about 32 months.