A bunion is a bump at the base of the big toe on the medial (inside) side. Hallux valgus is another more descriptive term used for this condition. A bunion is usually a complex deformity of the big toe that involves separation of the metatarsals and angulation of the toe away from the midline of the body (toward the lesser toes). Bunions occur in all age groups, and are much more common in women. The cause of bunions is thought to be partially hereditary and partially influenced by footwear (such as women's fashion shoes).
Bunions usually do not cause pain unless pressure from shoe wear occurs, or pressure from the deformed toe is applied to the second toe. Most people with a bunion have no pain when barefoot; however, bunions may develop redness and swelling if inflamed. A callus can develop under the bunion or under the ball of the foot at the base of the second toe due to weight transfer.