An ingrown toenail occurs when the edge of the nail grows down and into the skin of the toe. There may be pain, redness, and swelling around the nail.

An ingrown toenail can result from a number of things, but poorly fitting shoes and toenails that are not trimmed properly are the most common causes. The skin along the edge of a toenail may become red and infected. The great toe is usually affected, but any toenail can become ingrown.

Ingrown toenails may occur when extra pressure is placed on your toe. Most commonly, this pressure is caused by shoes that are too tight or too loose. If you walk often or participate in athletics, a shoe that is even a little tight can cause this problem. Some deformities of the foot or toes can also place extra pressure on the toe.

Nails that are not trimmed properly can also cause ingrown toenails.

• When your toenails are trimmed too short or the edges are rounded rather than cut straight across, the nail may curl downward and grow into the skin.
• Poor eyesight and physical inability to reach the toe easily, as well as having thick nails, can make improper trimming of the nails more likely.
• Picking or tearing at the corners of the nails can also cause an ingrown toenail.

Some people are born with nails that are curved and tend to grow downward. Others have toenails that are too large for their toes. Stubbing your toe or other injuries can also lead to an ingrown toenail.