A bunion is an abnormal, bony bump that forms on the joint at the base of your big toe. This big toe joint becomes enlarged, forcing the toe to crowd against your other toes. This puts pressure on your big toe joint, pushing it outward beyond the normal profile of your foot, and resulting in pain. Bunions can occur for a number of reasons, but a common cause is wearing shoes that fit too tightly. Bunions can also develop as a result of an inherited structural defect, stress on your foot or a medical condition, such as arthritis. Often, treatment involves conservative steps that may include changing your shoes, padding your bunion and wearing shoe inserts. Severe cases of bunions may require surgery.