Pressure sores are areas of injured skin and tissue.
They are usually caused by sitting or lying in one position for too long. This puts pressure on certain areas of the body. The pressure can reduce the blood supply to the skin and the tissues under the skin. When a change in position doesn't occur often enough and the blood supply gets too low, a sore may form. Pressure sores are also called bed sores, pressure ulcers and decubitus ulcers.