An ingrown toenail occurs when the edge of the nail, usually on the big toe, grows into the skin adjacent to it. This causes pain, and if left untreated may result in infection. Signs of an infection include redness, swelling, and discharge at the edge of the toenail. Inflammation may increase to the point where the skin at the edge of the toenail swells over the side of the nail.
Risk factors for an ingrown toenail include:
- Abnormal bone anatomy or position of the big toe
- Abnormal bone growth beneath the nail
- Poor-fitting shoes — too tight at the toes or too loose
- Trauma to toe