A bunion is a bony bump that forms on the joint at the base of your big toe. It forms when your big toe pushes against your next toe, forcing the joint of your big toe to get bigger and stick out. The skin over the bunion might be red and sore.

Wearing tight, narrow shoes might cause bunions or make them worse. Bunions also can develop as a result of an inherited structural defect, stress on your foot or a medical condition, such as arthritis.


Source: https://www.mayoclinic.org/diseases-conditions/bunions/symptoms-causes/syc-20354799