Inflamed swelling is a medical condition that can be caused by a variety of factors, such as infection, trauma, or an allergic reaction. Two common terms used to describe this condition are BOIL and ABSCESS. A BOIL is a tender, red bump filled with pus that is caused by a bacterial infection of a hair follicle or oil gland. An ABSCESS is a pocket of pus that forms in the body due to a bacterial infection. Both boils and abscesses can cause inflamed swelling.