Saline is 0.9% sodium chloride solution, wet compresses have anti-inflammatory, cleaning and astringent effects. 1. Anti-inflammatory, astringent effect: saline wet dressing gauze, through the surface water evaporation to make the local temperature drop, reduce local inflammation and congestion. 2. Cleansing effect: saline wet compresses can make the scabs, scales soften and easy to remove, but also remove exudate, keep the wound clean, which is conducive to promoting wound healing. In general, saline relative to the human isotonic fluid, the human skin is generally not harmful.