Ingrown Toenail (Onychocryptosis)

Updated: Sep 16, 2021
Author: Thomas E Benzoni, DO, MT(ASCP); Chief Editor: Trevor John Mills, MD, MPH 


Practice Essentials

Ingrown toenails (unguis incarnatus), or onychocryptosis, are a common problem, and causes include poorly fitting (tight) footwear, infection, improperly trimmed toenails, trauma, and heredity. The great toe is the most commonly involved,[1]  with the lateral side being involved more commonly than the medial side.[2, 3, 4]  The ingrown nail is often diagnosed in schoolchildren, adolescents, young adults, and pregnant women.[1]  The underlying cause of this condition is a foreign body reaction. When the nail bed is compressed from the side, the edge of the nail penetrates the cuticle. A foreign body reaction is set up by the presence of the keratinaceous nail material in the flesh of the toe.[5, 6]

Ingrowth of the toenail is generally thought to be multifactorial, including the following:

  • Nail length: Cutting the nail so short that it is not constrained by the distal portion of the cuticles, allowing side slippage and penetration of the lateral nail bed by the nail substance.

  • External pressure: Wearing shoes that are so tight that they compress the ridges of the cuticles against the relatively stiff nail material, turning the nail into a cutting surface.

There are 3 stages of ingrown nails, as follows[7] :

  • Stage 1: Mild erythema edema and pain with pressure.

  • Stage 2: Significant erythema, edema, local infection, and discharge.

  • Stage 3: Granulation tissue formation and hypertrophy of the lateral wall besides the significant erythema, edema, and discharge.

This disorder is not found in the preambulatory stages. Rare in preteens, it is more common in teenagers, and its occurrence increases throughout life. Patients with an ingrown toenail have a painful, swollen, and tender toe. When infection is present, the patient may have local discharge. Important components of the history include a previous history of risk factors for diabetes and arterial insufficiency. The affected toe has all the classic signs of infection: pain, edema, erythema, and warmth. Lymphangitis is rare. The affected side is readily apparent. Inspection for other contributing causes, particularly mycoses, is important.

Radiography should be considered when it is necessary to rule out osteomyelitis (rare) or in the setting of trauma to rule out toe fractures (common).


Packing, taping, gutter treatment, and nail braces are options for relatively mild cases of ingrown toenails, whereas surgery is exclusively done by physicians, and phenolization of the lateral matrix horn is now the safest, simplest, and most commonly performed method with the lowest recurrence rate.[8, 9, 10, 11, 12, 13, 14]  Nail phenolization is indicated when partial and definitive removal of the nail plate is necessary.[10, 11]

Lateral plate avulsion with chemical matricectomy is considered the treatment of choice for ingrown toenails. Phenol is the most widely used cauterant, followed by 10% sodium hydroxide, and then  trichloroacetic acid. Phenol is effective but associated with prolonged postoperative drainage. Sodium hydroxide is considered to be equally efficacious as phenol but has the side effect of intense pain in the initial days after treatment. Trichloroacetic acid has also been found to be as efficacious as phenol.[11, 15, 16, 17]

(An ingrown toenail is shown in the photo below.)

Appearance of typical ingrown toenail. Appearance of typical ingrown toenail.

Follow-up and prevention

The principal morbid condition of ingrown toenail is pain. However, it can be the initiating pathway for more serious disorders in certain patients at risk, especially those with diabetes or arterial insufficiency. Particular attention must be paid to high-risk patients. Referral to specialty clinics for follow-up (eg, surgeon, podiatrist) is recommended for these patients.

Preventive measures include the use of properly fitted footwear and correct trimming of nails. Shoes should have a toe box large enough to fit the toes without pressure and to allow for normal spreading of the toes with walking. Nails should be cut straight across with clean, sharp, preferably bullnose-type nail trimmers (curve is reverse of common fingernail clippers). Nails should not be cut shorter at the lateral edges.

Recurrence and/or regrowth of the treated side occurs in 10-30% of cases. According to a Cochrane Database review, surgical interventions are more effective than nonsurgical interventions in preventing ingrown toenail recurrence. Postoperative treatments generally do not reduce the risk of infection, nor do they shorten healing time.[18]





Medical Care

Once nails have started to grow in, the basement membranes of the cuticle are open to bacterial invasion, and action is needed to forestall progression.[19]

The edge of the nail should be elevated from the bed. This elevation can be accomplished by simply rolling a cotton wisp from the lateral side of the nail gently under the edge of the nail (in the case of a lateral ingrowth). Forcing the cotton wisp in from the tip is much more painful. If the nail is too ingrown to do this without pain, try soaking the foot in warm water. Soaking may soften the nail enough to allow elevation of the edge without much pain.

If soaking fails, perform a digital block before elevating the nail edge. The toe is exquisitely sensitive. The block may hurt more than the procedure if it is not performed slowly with a small (30-gauge) needle and buffered lidocaine.

Partial nail removal with cauterization of the nail matrix is curative in 70-90% of cases.[20]  Alternatively, part of the nail plate may be removed by laser.[21]  However, there is little to no advantage to the use of the laser over chemical cautery.

Chemical Cautery

Chemical cautery of the nail matrix can be done by using phenol or 10% sodium hydroxide.[22, 7, 23, 24]  Obtain informed consent; consent should be obtained by the physician and not delegated. Make no guarantees of cure or lack of complications; explain the risk of infection, regrowth, and reoccurrence; and discuss the proposed procedure.

Prepare and drape the toe by using povidone-iodophor or a skin cleanser of choice, and perform a digital block at the metatarsal head or proximal phalanx. Use buffered lidocaine (usually without epinephrine, although there is no evidence to support this recommendation), and inject 1 mL at each digital nerve.

Using a nail cutter, elevate the ingrown portion of the nail, rolling the nail from the ingrown side toward the midline of the toe (shown in the photo below). Be sure to expose the germinal end of the nail (this end has a soft, feathered edge). The proximal end is under the cuticle and usually is white. Cut about one-fourth to one-third of the nail, perpendicular to the end of the nail. Discard the piece after showing it the patient.

Cutting the nail. Cutting the nail.

Place a cotton-tipped applicator, soaked in super-saturated phenol or 10% sodium hydroxide, into the proximal sulcus exposed by removal of the germinal portion of the nail (shown in the photo below). Wait 60 seconds; repeat this step. Rinse the site, especially the sulcus, with rubbing alcohol. Use an alcohol-saturated applicator to ensure removal of all chemical.

Cauterizing the matrix. Cauterizing the matrix.

The toe after the completed procedure is shown in the photo below.

Appearance of toenail at end of the cauterizing pr Appearance of toenail at end of the cauterizing procedure.

Apply a light gauze dressing, and instruct the patient to change the gauze the next day and then daily for 3-5 days. The patient should expect a slight discharge as the body cleanses the nail bed. Importantly, this discharge should occur as the site improves in appearance; discharge and increasing signs of inflammation may mean infection or an incomplete removal of the nail fragments. (Also see Ingrown Toenail Removal.)

Consultation is encouraged for those patients with risk factors (eg, those with diabetes or compromised circulation) related to either the disease or the procedure.[25]

Surgical Care

Surgical procedures for ingrown toenails are performed under local anesthesia, including digital block, metatarsal block, and transthecal anesthesia. Surgical options for ingrown toenail include the following[26, 27, 15, 28, 29, 17] : 

  • Spicule excision and partial matricectomy, which is the excision of the affected part of the nail with a partial mechanical matricectomy.
  • Chemical partial matricectomy, which is generally performed using phenol and is associated with a higher success rate than mechanical matricectomy. 
  • Wedge resection of the toenail and nail fold, which consists of excision of the affected part of the nail plate, partial matricectomy, and wedge dissection of the nail bed and the hypertrophic nail fold.
  • Excision of the affected nail and total matricectomy, which  is a more radical approach, consisting of excision of the affected nail, nail bed, and total chemical or mechanical matricectomy.
  • Soft tissue nail-fold excision technique does not touch the nail and consists of wide excision of the soft tissue.
  • Other techniques include electrocautery, radiofrequency ablation, and carbon dioxide laser ablation, have become the newest form of ingrown toenail management.

Surgical approaches to treatment are usually reserved for stage 3 onychocryptosis (ranulation tissue formation and hypertrophy of the lateral wall besides the significant erythema, edema, and discharge) or for those for whom nonsurgical treatments have been unsuccessful.[26]

In a retrospective study, by Romero-Perez et al, of 520 patients who underwent ingrown toenail surgery, surgical matricectomy was associated with a lower recurrence rate (8.2%) than chemical matricectomy with phenol (CMP) (17.8%), more pain (5.7/10 vs. 3.6/10), higher risk of infection (15.3% vs. 2.9%), and lower cosmetic satisfaction (7.3/10 vs. 8.0/10). [27]



Medication Summary

Medications are needed for only those with complications. Antibiotics are not indicated unless lymphangitic spread is noted. Antifungal agents are needed for onychomycosis. Ibuprofen or acetaminophen is used for pain.


Class Summary

Pain control is essential to quality patient care. It ensures patient comfort, promotes pulmonary toilet, and enables physical therapy regimens. Most analgesics have sedating properties, which are beneficial for patients who have painful lesions.

Ibuprofen (Advil, Motrin, Nuprin, and Genpril)

Usually the label directions are sufficient for the treatment of mild to moderate pain, if no contraindications are present. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

Acetaminophen (Tylenol, Aspirin Free Anacin)

DOC for pain in patients with documented hypersensitivity to aspirin or NSAIDs, those with upper GI disease, or those taking oral anticoagulants.

Acetaminophen and Codeine (Tylenol with codeine)

Drug combination indicated for the treatment of mild to moderate pain.