Bunions can be caused by: a genetic (hereditary) tendency to have a weakness of this joint a joint problem such as osteoarthritis or rheumatoid arthritis In most cases it isn't clear why a bunion develops. Bunion symptoms Bunion's can cause: pain and stiffness of the big toe joint swelling of the big toe joint - the foot may become so wide it can be difficult to find wide enough shoes difficulty walking arthritis in the big toe Most symptoms settle with time.