What is bursitis?

What is bursitis?

Bursitis is the painful swelling of a small, fluid-filled sac called a bursa. These sacs cushion areas where bone would otherwise rub on muscle, tendons or skin. By padding these areas, bursae (plural for bursa) decrease friction, rubbing and inflammation. Although you have bursae throughout your body, bursitis most often occurs around the joints.

Bursitis happens when a bursa becomes irritated by overuse or excess pressure. The pain from an inflamed bursa may be sudden or build up over time.