it is curved and grows into the skin, usually at the nail borders (the sides of the nail). This digging in of the nail irritates the skin, often creating pain, redness, swelling and warmth in the toe.
Causes of ingrown toenails include:
Heredity: in many people, the tendency for ingrown toenails is inherited.
Trauma: Sometimes an ingrown toenail is the result of trauma, such as stubbing your toe, having an object fall on your toe or engaging in activities that involve repeated pressure on the toes, such as kicking or running.
Improper trimming: The most common cause of ingrown toenails is cutting your nails too short. This encourages the skin next to the nail to fold over the nail.
Improperly sized footwear: Ingrown toenails can result from wearing socks and shoes that are tight or short.
Nail conditions: Ingrown toenails can be caused by nail problems, such as fungal infections or losing a nail due to trauma.