Ingrown nail

Onychocryptosis (also known as an “Ingrown nail,” or “Unguis incarnatus”) is a common form of nail disease. It is an often painful condition in which the nail grows so that it cuts into one or both sides of the nail bed. While ingrown nails can occur in both the nails of the hand and feet, they occur most commonly with the toenails.



The main cause for onychocryptosis or “ingrown nail” is improper footwear including shoes with inadequate toe-box room and tight stockings that apply top and or side pressures; next is the damp wet atmosphere toes are subjected to all day in enclosed shoes, softening the nail-plate and swelling the epidermis keratin, which eventually increases the convex arch permanently; next is genetics; and last are trauma and disease.

Improper cutting of any nail may cause the nail to cut into the side-fold skin from growth and impact, whether or not the nail is “ingrown” (onychocryptosis). The nail bends inwards or upwards depending on the angle with which it has been cut. Looking from the perspective of the owner, when cutting the nail, if the cutting tool, such as scissors, are in an attitude where the lower blade is closer to the toe than the upper blade then that will cause the toenail to start growing from its base upwards. Vice versa, when the lower blade is farther than the upper blade, the toenail will turn inwards. The process is visible along the nail as it grows, appearing as a warp that advances towards the end of the nail. The upper corners turn more easily than the center end of the nail. As people cut their nails by holding the tool always in the same angle, they induce these conditions by accident, while as the nail turns closer to the skin, it becomes harder to fit the lower blade in the right attitude under the nail. When cutting a nail, it is not just the right angle that is important, but also how short it is cut. A shorter cut will bend the nail more, unless the cut is even on both top and bottom of the nail.

Causes include:

  1. Bad maintenance, including cutting the nail too short, rounded off at the tip or peeled off at the edges instead of being cut straight across
  2. Ill-fitting shoes, as those that are too narrow or too short can cause bunching of the toes in the developmental stages of the foot (frequently in those under 21), causing the nail to curl and dig into the skin
  3. Trauma to the nail plate or toe, which can occur by stubbing the toenail, dropping things on the toe or going through the end of the shoes (as during sports or other vigorous activity), can cause the flesh to become injured and the nail to grow irregularly and press into the flesh
  4. Predisposition, such as abnormally shaped nail beds, nail deformities caused by diseases, or a genetic susceptibility to nail problems like ingrowth

A more physiologically sound hypothesis is that an “Ingrown Toenail” is actually a problem where there is too much skin around the nail (“Overgrown Toeskin“) – the nail is not the problem. Vandenbos and Bowers theorized that pressure necrosis of the soft tissues surrounding the nail due to weight bearing is the primary cause of ingrowing toenails. They wrote “the term ‘ingrown toenail’ is unfortunate in that it incriminates the nail as the causative factor and is responsible for the fact that most operative and conservative treatments are directed toward the nail. It is our thesis that persons who develop this condition have an unusually wide area of tissue medial and lateral to the nail and that with weight bearing this tissue tends to bulge up around the nail. When such persons trim the nail in a curved or rounded fashion instead of straight across, further bulging of soft tissue is allowed, and as the nail grows out, pressure necrosis of soft tissue occurs. If our thesis that the fault lies not with the nail but with an excess of soft tissue is correct, treatment by removal of a segment of nail is not rational. It increases the relative amount of soft tissue and predisposes to recurrence and at the same time inept attempts to remove some nail matrix lead to faulty regrowth of the nail. The logical conclusion is that soft tissue should be excised, so that with weight bearing there will be no tissue to bulge up across the nail.

One study compared patients with ingrown toenails to healthy controls and found no difference in the shape of toenails between patients and controls and suggested that treatment should not be based on the correction of a non-existent nail deformity. Ingrown toenails are caused by weight-bearing (activities such as walking, etc.) in patients that have too much soft tissue (skin) on the sides of the nail. Weight bearing causes this excessive amount of skin to bulge up along the sides of the nail. The pressure on the skin around the nail results in the tissue being damaged, resulting in swelling, redness and infection.

In the past (and still today) the most common treatments are mainly directed at the nail (Paradigm Paralysis). Treatments often include removal of part or all of the nail. But since the nail is normal and the problem of too much skin around the nail is not treated, this often results in the problem returning or in deformity/mutilation of the nail. Not surprisingly, patient satisfaction reflects this.



Symptoms of an ingrown nail include pain along the margins of the nail (caused by hyper granulation that occurs around the aforementioned region), worsening of pain when wearing shoes or other tight articles, and sensitivity to pressure of any kind, even the weight of bed sheets or a duvet. Bumping of an affected toe with objects can produce sharp, even excruciating, pain as the tissue is punctured further by the ingrown nail. By the very nature of the condition, ingrown nails become easily infected unless special care is taken to treat the condition early on and keep the area as clean as possible. Signs of infection include redness and swelling of the area around the nail, drainage of pus and watery discharge tinged with blood. The main symptom is swelling at the base of the nail on whichever side (if not both sides) the ingrowing nail is forming.


The most common place for ingrown nails is in the big toe, but ingrowth can occur on any nail. Ingrown nails can be avoided by cutting nails straight across; nails should not be cut along a curve, nor should they be cut too short. In both cases, the important thing to avoid is cutting the nail shorter than the flesh around it. Footwear which is too small, either in size or width, or those with too shallow a ‘toe box’ will exacerbate any underlying problem with a toenail.

It may not be so critical that the nails be cut perfectly ‘straight across’ as this may imply that they be squared at the corners. Leaving sharp square corners may be uncomfortable and cause snagging on socks. The important thing to keep in mind is that you want to be able to see the corners. You should be able to see the side edge of the nail as it meets the front edge of the nail. This way, you can be sure there is no ‘splinter’ veering off to the side and growing into your toe. Careful filing of the corner is reasonable. For some people the nail curves down on the sides, in this case it would be difficult to ever see the side edge of the nail plate and this cutting method does not apply. Some nails require cutting of the corners far back to remove the edge that digs into the flesh, this may be done as a partial wedge resection at your podiatrist’s office.

Ingrown toe nails can be caused by injury, commonly blunt trauma where the flesh is pressed against the nail causing a small cut that swells. Also, injury to the nail can cause it to grow abnormally, making it thicker or wider than normal or even bulged or crooked. Stubbing the toenail, dropping things on the toe and ‘going through the end of your shoes’ in sports are common injuries to the digits. Injuries to the toes can be prevented by wearing properly fitting shoes, especially when working or playing.

One myth is that a V should be cut in the end of the ingrown nail; this myth is untrue. The reasoning of the myth is that if one cuts a V in the nail, the edge of the nail will grow together as the nail grows out. This does not happen – the shape of the nail is determined by the growing area at the base of the toe and not by the end of the nail. A notch does no good, and may do harm if it is cut too deeply.


Treatment of ingrown nails ranges from soaking the afflicted area to surgery. The appropriate method is dictated by the severity of the condition. In nearly all cases, drainage of blood or watery discharge should mean a trip to the doctor, usually a podiatrist, a specialist trained explicitly to treat these conditions. Most practitioners agree that trying to outwait the condition is nearly always fruitless, as well as agonizing, but it can be done as long as the condition is not too severe and if the individual has a high pain threshold.