Podiatrist - Dr. Harvey Jacobs of Somerset New Jersey discusses the symptoms, causes and treatment for ingrown toenails. br br Ingrown nails, the most common nail impairment, are nails whose corners or sides dig painfully into the soft tissue of nail grooves, often leading to irritation, redness, and swelling. Usually, toenails grow straight out. Sometimes, however, one or both corners or sides curve and grow into the flesh. The big toe is usually the victim of this condition but other toes can also become affected. br Ingrown toenails may be caused by: br •Improperly trimmed nails (Trim them straight across, not longer than the tip of the toes. Do not round off corners. Use toenail clippers.