What Causes Bunions? Bunions typically develop due to a mix of factors rather than a single cause. Key contributors include family history, abnormal bone structure, increased foot motion, and shoe choices. Prolonged pressure on the big toe joint, often from years of wearing poorly fitting shoes or other factors, can push the joint out of alignment and toward the other toes. This misalignment leads to the formation of a bunion on the metatarsophalangeal (MTP) joint as your body adjusts to the shifted position of your toe. Common causes of increased pressure on the big toe joint include: Wearing narrow or pointed shoes that squeeze the toes. Abnormal foot mechanics or walking patterns. Health conditions causing inflammation, such as rheumatoid arthritis or lupus. Standing for extended periods or working on your feet. Unsightly and uncomfortable foot issues like athlete's foot and bunions can be a real nuisance. A bunion is a bony growth that occurs at the base of the bi...