Bunions are usually caused by prolonged pressure put on the feet that compresses the big toe and pushes it toward the second toe. Over time, the condition may become painful as extra bone grows where the base of the big toe meets the foot.
Update Date 3/10/2016
Updated by: C. Benjamin Ma, MD, Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, CA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.