What is the first step in treating a burn?

Cooling the burn with running water is essential as it helps to lower the temperature of the burn area, which can minimize tissue damage and reduce pain. The cooling process should ideally be done within the first few minutes after a burn occurs, as this can significantly help in lessening the severity of the injury. Using cool running water helps to stop the burning process and can provide immediate relief from the heat and pain associated with the burn.

The other options are not suitable as initial treatments for burns. Covering the burn with a tight bandage can trap heat and exacerbate damage. Applying butter or oil can cause the burn to retain heat and increase the risk of infection. Checking for signs of dehydration, while important in the overall assessment of a patient's condition, does not address the immediate need to care for the burn itself. Thus, cooling the burn with running water is the most effective first step in the management of burn injuries.