Onychocryptosis, or an ingrown toenail, is a common and frequently painful foot problem. For some people, it could be debilitating.

In this article, we examine the symptoms of onychocryptosis and what causes toenails to become ingrown. We also look at the potential treatment and prevention methods for an ingrown toenail.

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Onychocryptosis is the medical term for an ingrown toenail that usually affects the big toe. It occurs when the toenail embeds into the surrounding skin of the toe by growing into the skin or the skin extending over the edges of the nail.

Around 2.5–5% of the general population have an ingrown toenail at any one time. It is most common in children and young adults aged 10–20 and older adults aged 50–60. Ingrown toenails account for around 20% of all foot problems.

People with diabetes, poor blood circulation, or decreased sensitivity in the feet are more likely to have severe onychocryptosis.

The symptoms of an ingrown toenail may include:

  • the toe feeling hard or tender to touch
  • swelling or redness surrounding the nail
  • pus or discharge that signals an infection
  • the toe being warm or hot
  • experiencing pain when wearing shoes, walking, or putting any pressure on the foot or toe

Doctors may classify an ingrown toenail in the following categories depending on the symptoms:

  • Mild (stage 1): The nail fold and the toe becomes swollen and red, with pain that worsens with pressure.
  • Moderate (stage 2): The symptoms are the same as a mild ingrown toenail but with an infection. There may be bleeding or discharge and red, bumpy tissue around the site.
  • Severe (stage 3): In addition to the symptoms of a moderate ingrown toenail, the toe has chronic inflammation with overgrown skin tissue forming at the site where the nail embeds into the skin.

Many factors can lead to an ingrown toenail. In fact, more than one factor often causes onychocryptosis.

The following factors all increase the risk of having an ingrown toenail:

  • Improper nail trimming technique: cutting the toenail in a curve instead of straight or cutting it too short may cause the nail to grow inward
  • Constricting footwear: shoes that are too tight or do not fit correctly at the toes
  • Trauma to the toe: injuries, such as stubbing the toes or someone accidentally stamping on them
  • Obesity: increased soft tissue in the feet may mean shoes are too tight, while extra weight may apply more pressure on the nail folds
  • Underlying conditions: diabetes, thyroid conditions, and renal disorders may swell the feet, increasing pressure on the toes
  • Abnormal nail or toe shape: pincer or trumpet nails or bony abnormalities in the toes
  • Hyperhidrosis: excessive sweating may make the nail plate and the surrounding tissue too soft
  • Fungal infection: these infections may cause the nail to become thick or wide
  • Onychotillomania: the urge to bite or chew the toenails, or pull and pick at them, can cause damage to the nails, encouraging growth into the skin and infection

The American Academy of Orthopedic Surgeons (AAOS) also states that sometimes the cause is congenital, meaning the person was born with a nail too large for the toe.

A doctor may recommend one or several treatments, depending on the severity of the ingrown toenail, its cause, and whether there are any underlying conditions.

For mild ingrown toenails, a doctor may recommend:

  • soaking the foot in warm water 3–4 times a day for 10–20 minutes
  • keeping the foot as dry as possible when not soaking it
  • wearing comfortable shoes or sandals to give the toes plenty of space
  • taking over-the-counter pain relief, such as ibuprofen or acetaminophen
  • using dental floss to gently separate the edge of the ingrown toenail from the skin and packing to hold it away from the skin or pulling the nail fold from the nail by using a taping technique

For more severe ingrown toenails with an accompanying infection, a doctor may recommend a different treatment or a minor surgical procedure to treat the condition, such as:

  • using a nail brace to lift the nail clear of the skin
  • trying a gutter splint as support under the nail to help it grow above the skin edge
  • removing portions of the nail that have overgrown, or even parts of the nail bed, to prevent the nail from growing back
  • using a chemical to remove the nail over several weeks
  • shortening the distal phalanx, the bone at the tip of the toe

Surgeons perform surgical procedures using a local anesthetic. A doctor may apply antibiotic ointment to the wound after the surgery. A person may also require oral antibiotics.

Recovery from a surgical procedure takes a few weeks. However, it may take 2–4 months for the toenail to grow back. Some surgical procedures involving removing parts of the nail bed may prevent the toenail from growing back.

The following tips may help reduce the risk of an ingrown toenail developing:

  • Cut toenails straight across when trimming: Try not to cut them too short or round off the edges of the nail.
  • Wear comfortable shoes that do not constrict the toes: Wide or open-toe shoes are best. If wearing heels, use cushioning to prevent the foot from sliding forward in the shoe and compressing the toes.
  • Keep the feet clean and dry: Wash feet regularly and change socks if they are sweaty.
  • Ask for help with trimming: A person can get help from a friend or relative or visit a podiatrist when having difficulty trimming nails.
  • Treat underlying conditions correctly: Conditions such as diabetes increase the risk of onychocryptosis.

People with onychocryptosis should contact a doctor if:

  • self-help measures do not work to ease the pain or symptoms
  • the symptoms such as pain, swelling, discharge, or redness, get worse
  • the toe is not healing after a surgical procedure

An untreated infection in the toe may spread to the rest of the toe or even into the bone, so it is important to see a healthcare professional for advice.

Onychocryptosis, or an ingrown toenail, is a common foot problem. It is most likely to occur in children, young adults, and people in their 50s.

Symptoms of onychocryptosis may include:

  • swelling
  • redness
  • pain
  • discharge

Treatment and prevention strategies for onychocryptosis may include:

  • soaking the foot
  • packing the space between the nail and the skin
  • wearing open-toed shoes
  • surgical procedures to remove parts of the nail, nail bed, or surrounding tissue

Incorrect nail trimming and tight shoes could be the leading causes of ingrown toenails.