An ingrown toenail, also known as onychocryptosis or unguis incarnatus, is a common and painful condition of the toe.
Ingrown toenails occur when the edge or corner of a toenail grows into the soft flesh next to the nail. Once the edge of the nail breaks through the skin the result is pain and inflammation.
If left untreated, an ingrown toenail can progress to an infection (cellulitis) or become a reoccurring problem. It may become an abscess or spread and infect the underlying bone. Any nail can become ingrown, but the condition is usually found in the big toes.
Common causes include:.
• Improper shoe fitting – tight-fitting shoes or high heels cause the toes to be compressed together and puts pressure on the toenails
• Trimming nails incorrectly or too short. They should be cut straight across, not rounded.
• Injuring your toe – either an acute injury, such as stubbing your toe, or trauma caused by athletic activities in which you repeatedly put pressure on your toes for long periods of time (such as ballet or soccer)
• Having unusually curved toenails (known as pincer nails).
• Damage by picking or tearing the corners of your toenails
• Improper foot hygiene, such as not keeping your feet clean or dry – ingrown toenails are more common in people with sweaty feet, such as adolescents and athletes. This makes your skin soft and easier for toenails to dig in.

Treat your ingrown toenail as soon as possible to avoid worsening symptoms.