An ingrown nail is the result of a nail growing into the skin that surrounds it. This often occurs at either edge of the big toe. Ingrown nails may be caused by improper trimming, inherited nail deformities, injuries, fungal infections, or pressure.
Abnormally thick or crumbling nails may be caused by injuries, pressure from shoes, fungal infections, or conditions such as diabetes, psoriasis, or vascular disease. Eventually, the nail may loosen and fall off.
A black-and-blue nail is usually caused by sudden or repetitive injury to a toe. This might occur during sports that involve running or stopping quickly, such as tennis or basketball. The injury may also result from a heavy object falling on a toe.
Note: New treatments are now available to cure fungal infections of the nails which were previously difficult to cure.