When a toenail is ingrown, it is curved and grows into the skin, usually at the nail borders. This irritates the skin around the nail and often causes redness, pain, swelling and warmth in the toe. On occasion, the ingrown toenail can break the skin, allowing bacteria to enter and an infection to occur. The most common symptoms of an infection are drainage and a foul odor. There are many causes of ingrown toenails, which include: genetics, trauma to the toe, improper trimming of the toenail, improperly fitted shoewear and nail conditions such as fungal infections. Treatment of ingrown toenails varys and can include oral antibiotics and/or minor surgical procedures.