Q: What is a bunion? A: A bunion is a bony growth on the side of the base of your big toe. Both pressure from your shoes and motion in the big toe joint can cause pain. Bunions can be due to heredity, or a biomechanical problem (over-pronation). Wearing a pad over the bunion can help to reduce friction on the inside of your shoes. If you think over-pronation is the cause, try a custom orthotic and find shoes that fit properly. More painful bunions often require surgical correction.