In short

Subungual hematoma or blue toenail

A subungual hematoma (blood under the toenail) is a collection of blood underneath the toenail resulting from injury or repeated trauma to the nail bed. The condition is often painless, but some cases can be very sensitive.

See the causes See the long term complications See how to relieve yourself at home

Signs and Symptoms

Signs and symptoms of black toenails

  • Blue, purplish or black discoloration of the toenail
  • May cover the entire nail or be limited to one area
  • Often appears spontaneously
  • The nail may become loose or fall off
  • A sharp or dull pain may be present
  • There may be redness and swelling around the nail
  • In few cases, there may be bleeding or pus draining from under the nail

What are the causes of blue toenails

When the attachments of the toenail to the skin is injured, there may be bleeding and a hematoma may form underneath the nail. A common cause is direct trauma to the toenail, such as dropping a heavy object on your toe or falling and tripping over the toe. The condition can also result from repeated minor stress, like wearing ill-fitting shoes, hiking downhill, running or playing sports that involve sharp turns and movements.

When a direct impact to the fingernail is at fault, bleeding occurs quickly, causing additional pain and discomfort. In such cases, you may observe swelling or bleeding around the nail.

In cases of repeated micro-injury, the stress may be minor and barely noticeable, but with repetition the nail bed gradually weakens. Patients often notice the condition only after they’ve removed their shoes.

In rare cases, a subungual hematoma can be caused by a fracture of the phalanx bones located directly underneath the nail.

Progression and Consequences

Progression and consequences of blue toenails

In many cases, subungual hematomas present no complications but remain a cosmetic problem. Toenails grow at the rate of only 1 mm per month, meaning it can take as long as 12 months for the discoloration to fully disappear.

If the affected surface is large, the toenail may become loose and partially or completely fall off. This generally occurs as the nail grows out. A border (large line) then becomes visible between the new and injured parts of the nail.

Meanwhile, the damage to the nail bed and surrounding tissues disrupts the natural seal of the cuticle, putting the patient at risk of bacterial and fungal infections.

In rare cases, traumatic injury can irreversibly damage the nail matrix and cause the nail to continuously grow back with an irregular shape.  

Finally, after partial or full loss of the nail, the new growth may become ingrown, cutting into the surrounding skin.

How to relieve myself at home?

How to relieve a black toenail pain at home

Here are some tips to follow when symptoms first appear:

  • Wash the feet with a saline solution (3 tablespoons of salt in 2 litres of water) for 10 minutes once or twice a day.
  • Apply an antibiotic ointment like Polysporin to the swollen area 2 to 3 times a day. During the day, cover the nail with a Band-Aid.
  • Avoid tight, narrow shoes.

If symptoms persist after a few days, see a podiatrist.


Diagnostic of Subungual hematoma

A simple observation of the toenail is sometimes enough for a diagnosis. In cases of doubt, a sample of the toenail may be collected, or the podiatrist may order a biopsy. In trauma cases, x-rays may be necessary.

What can my podiatrist do?

What can my podiatrist do about blue toenails

Your podiatrist will be able to recommend the most appropriate course of treatment for your condition:

  • The podiatrist will need to pierce the nail and cleanse the nail bed to ensure the new nail grows back properly. This procedure is usually painfree but may be performed under local anesthetic if necessary.
  • If the problem is severe, the podiatrist may need to completely remove the nail under local anesthetic.
  • If a fracture is suspected, X-rays of the toe may be taken.
  • If there are signs of local infection, the podiatrist may prescribe an antibiotic ointment.
  • Finally, the podiatrist will follow up on the growth of the new nail.
How to prevent it?

How to prevent black toenails?

  • Keep your toenails cut short.
  • Wear appropriately sized shoes. One finger’s thickness should fit between your toes and the front edge of your shoes.
  • Wear shoes that provide adequate room for the toes.
  • Tie shoelaces tightly to prevent unnecessary movement of the feet inside the shoes.
  • Wear adequate footwear when doing heavy chores at home.
  • Watch where you’re going!
If my nail is black, that means it's dead and won't grow back.

The black colour is caused by the coagulation of blood at the injury site. Since dried blood remains trapped under the nail, the discolouration doesn't go away. But don't worry: the nail matrix is alive and will slowly produce a new nail. It's not uncommon for the injured nail to fall off as the new nail grows.

And if it was not ...

And if it was not blue toenails?

  • Onychomycosis (fungal infection)
  • Warts or calluses under the toenail
  • Ingrown toenail
  • Granuloma
  • Osteochondroma
  • Skin cancer
  • Diabetic foot ulcer
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