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 or side of the toe. Pain and inflammation at the spot where the nail curls into the skin occurs first. 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.
Any toenail can become ingrown, but the condition is usually found in the big toe.
Improper trimming of toenails can cause the corners of the nail to dig into the skin. Nails should be trimmed straight across, not rounded. Disorders such as fungal infections of the nail can cause a thickened or widened toenail to develop. Injury near the nail may cause an ingrown toenail. If a member of your family has an ingrown toenail, then you are probably more likely to develop one too.