An ingrown toenail is a painful condition of the toe. It occurs when a sharp corner of the toenail digs into the skin at the end of or side of the toe. Pain and inflammation at the spot where the nail curls into the skin occurs first. Later, the inflamed area can begin to grow extra tissue or drain yellowish fluid.

If left untreated, an ingrown toenail can progress to an infection or even an abscess that requires surgical treatment. Ingrown toenails are common in adults but uncommon in children and infants. They are more common in men than in women. Teenagers and young adults are most at risk.

Any toenail can become ingrown, but the condition is usually found in the big toe.