Scalded leaving cold water on the pain is due to the cold water cooling time is not enough and scalded skin peripheral nerve damage. General scalded with cold water rinse need about half an hour. 2. Scalded skin peripheral nerves are injured: the nerve endings on the skin will be injured after scalding, which is the root cause of the pain of scalding. Under running cold water, the blood vessels in the scalded area will contract, and the pain sensation will be reduced or disappeared. Once out of the cold water, the blood vessel contraction will be weakened, and the pain will appear. It is important to seek medical attention for burns.