A bunion is a bump on the base of the big toe joint. Bunions are caused when the bone at the joint moves and bends toward the other toes. The big toe may even overlap the others as this movement continues.
Bunions can cause severe pain because this big toe joint carries much of the body’s weight. Bunions run in families because of an inherited foot type that includes poor foot mechanics. Wearing tight or narrow shoes can aggravate the bunion. Those with flat feet or low arches are prone to bunions, as are people with arthritis or inflammatory joint disease.