Swelling and inflammation are your body’s reactions to injury. Following an injury, particularly to soft tissue, your body increases blood flow to the injured area in order to lock down the area and begin the repair process. However, increasing blood flow and fluids to one local area might cause pain, immobility, and increased pressure on neighboring tissues. Swelling and inflammation usually peak three days following an injury but can last up to six weeks, depending on the type of shoulder injury. After experiencing trauma, consult your doctor to determine how long your inflammation will last.