Bursitis is inflammation of a bursa, a small sac of fluid that cushions and lubricates an area where tissues—including bone, tendon, ligament, muscle, or skin—rub against one another. Bursae are located throughout the body, in and on joints and other places that are at risk of rubbing or pressure.

Bursitis can be caused by prolonged or repeated pressure on a bursa, by activities that require repeated twisting or rapid joint movement, by infection or systemic diseases such as arthritis, or by trauma. Symptoms of bursitis may include:

• Pain, especially with motion or pressure on the involved bursa.
• Swelling caused by increased fluid within the bursa.
• Redness and warmth.

Bursitis can often be treated at home by resting, applying ice or cold packs to the affected area, and avoiding the activities that irritate the area or cause pain. If the area is warm and red, an infection may also be present, which requires medical evaluation.

Traumatic bursitis is bleeding in a bursa caused by a direct blow to the bursa. Septic bursitis is an infection of a bursa, which sometimes results from traumatic bursitis. Septic bursitis requires medical treatment, which may include surgery and/or a hospital stay for intravenous (IV) antibiotic therapy.