An ingrown toenail occurs when the edge of the nail grows down and into the skin of the toe. causes An ingrown toenail can result from a number of things. poorly fitting shoes and toenail that are not properly trimmed are the most common causes. The skin along the edge of a toenail may become red and infected. the great toe is affected often, but any toenail can become ingrown. Ingrown toenails may occur when extra pressure is placed on your toe. this pressure is caused by shoes that are too tight or too loose. if you walk often or participate  in athelatics, a shoes that is even little tight can cause this problem. deformitits of the foot or toes can also place extra pressure on the toe. Nails that are not trimmed properly can also cause ingrown toenails. Toenails that are trimmed too short ,or if the edges are rounded rather than cut straight across may cause the nail to curl downward and grow into the skin  poor eyesight inability to reach the toea easily or having thick nais can m