Painful ingrown nails may be congenital, caused by an overcurvature of the nail, or an imbalance between the width of the nail plate and the nail bed.

Toe injuries that change the nail's contour also can lead to an ingrown toenail. Toe deformities (such as a bunion that forces the big toe to lean toward the second toe), high-heeled or narrow, pointed shoes can put pressure between the nail and soft tissues, eventually forcing the nail to grow into the skin.

Symptoms:
Redness, swelling and infection make the toe very painful. Ingrown nails can also be accompanied by other toe disorders, such as excess surrounding tissue or an outgrowth of bone beneath the nail.

Treatments:
Surgery is often necessary to ease the pain and remove the offending nail. Only a portion of the nail may be removed. If the entire nail is affected or there is a severe nail deformity, the nail plate and matrix (the cells that grow the nail) may be completely removed.