A bunion is a painful bony bump that forms on the joint at the base of your big toe. It happens when the bones in the front part of your foot shift out of place, causing the tip of your big toe to get pulled toward the smaller toes while the joint at the base pushes outward. This creates a bulge on the side of the foot that can become red, swollen, and sore.

Bunions often develop slowly over years, sometimes from wearing shoes that squeeze the toes together (especially narrow, pointed shoes or high heels), but genetics plays a big role too. Some people inherit foot shapes that make bunions more likely to form. Athletes, dancers, and people who spend lots of time on their feet may also develop them.

The bump is actual bone that has moved out of alignment, not just swollen tissue or skin. This is why bunions can make it hard to find comfortable shoes and why they sometimes hurt when walking or running. Doctors can treat bunions with special pads, roomier shoes, or exercises, though severe cases might need surgery to realign the bones.