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Black Toenail

Reviewed by
Dr. Sara Karamloo

There are many causes of black or dark toenails, but the most common cause is trauma. When trauma occurs to a nail resulting in discoloration it is referred to as a subungual hematoma, which simply means there is a collection of blood underneath the nail.

This collection not only causes the nail to become discolored, it also generates a tremendous amount of pressure, leading to intense pain. In many cases, medical treatment is advised not only to relieve this discomfort, but to remove the entire nail and examine the nail bed for significant laceration or exposed bone.

Although everyone is susceptible to black toenails resulting from accidental trauma, athletes and those who often walk barefoot are at a higher risk. Black toenails can be caused by a fungal infection, which is common in immuno-compromised patients, or they may indicate underlying melanoma (a malignant tumor consisting of dark-pigmented cells called melanocytes).

black toenails

Black Toenail Symptoms

Symptoms of a black toenail may include:

  • Discoloration, which may be reddish, purplish, brownish, or black
  • Pain
  • Foul odor
  • Discharge from underneath nail

Although symptoms are not always present, there are a wide range of symptoms that can occur. In the case of an underlying infection, there may be pain associated with redness, swelling, foul odor, and discharge. Often the nail comes loose and falls off on its own within days of the trauma due to the blood collection causing it to separate from the nail bed.

What Causes a Black Toenail?

There are several ways your toenail could turn black, including:

  • Injury or trauma to the nail or affected toe
  • Fungal infection
  • Repeated trauma from running or athletic activities
  • Ill-fitting or tight shoes
  • Malignant melanoma (an extremely rare condition)

When to See Your Doctor

Often a black toenail will eventually fall off and regenerate on its own. If pain or signs of infection (e.g., pus, discharge, foul odor, fevers, chills) are not present, you may not need to seek medical treatment right away. Even so, keep in mind that when the nail returns it may be abnormal as a result of the trauma. Furthermore, anytime the discoloration covers 25 percent or more of your nail, you should seek medical attention immediately. In such cases, it is more likely that the nail bed is severely lacerated or that there is exposed bone under the nail. If left untreated, this condition can lead to a bone infection (osteomyelitis) that will require long-term IV antibiotics and a possible amputation of the digit. If you are concerned, you should call your doctor and make an appointment.

Diagnosing Black Toenails

In most circumstances your visit to your podiatrist will be simple and for reassurance only. They will check to make sure you have no open or closed fractures of the affected toe, no underlying infection, and no need for further intervention. If trauma was involved, depending on the type and severity of the injury and what percentage of the nail is discolored, your doctor may decide to remove your nail in order to examine the nail bed for lacerations and exposed bone. If you have not been injured and have noticed progressive discoloration, your doctor will need to order specific tests, possibly including a biopsy. He or she will ask you about your activities leading up to discoloration and about your medical and family history.

Black Toenail Treatment

It is important to know that in some cases medical treatment is unnecessary, especially if minor trauma was involved. In these cases, the black toenail will eventually fall off on its own or grow out. If you are in doubt, however, you should make an appointment with a podiatrist. Your podiatrist will determine the cause and severity of the problem, which will determine the treatment he or she recommends. If your doctor does not see a need for medication or drainage, the nail may be left alone to heal on its own. On the other hand, if the injury is cause for concern a local anesthetic will be administered and the nail will be removed for examination of the nail bed. If a laceration is present it will have to be washed out and possibly sutured. If the hematoma only needs to be drained to relieve the pain and pressure, there are three ways your podiatrist can do this:

  • Removal: The nail will be removed and the area will be cleaned, thereby removing the hematoma. In some instances the nail may be replaced on the nail bed as a protective barrier.
  • Needle: A sterile large-gauge needle can be used to create a small hole in the nail to allow the fluid to drain.
  • Cautery: A battery-operated device burns a hole in the nail until the blood begins to drain.

After treatment, you should expect the hole to remain in the nail until it grows out. Again, you should never assume the discolored toenail will regrow normally. Seeing a podiatrist, especially when the toenail first changes color, can improve the chances that your toenail will return to its natural state and color. Your doctor may recommend a follow-up visit within a week after treatment. You may be advised to soak your foot with Epsom salt and lukewarm water twice daily for ten to fifteen minutes at a time, after which an antibiotic ointment and a dry, sterile bandage will be applied.

Your recovery time will depend on the severity of the injury, the type of treatment used, and how well you respond to treatment. On average, black toenails can take up to a few months to completely heal and return to normal, as nails tend to grow at a rate of approximately 3mm a month.

Preventing Black Toenails

Here are some tips to help you prevent black toenails:

  • Keep toenails trimmed properly, not too short and straight across.
  • Wear properly fitting shoes. Shoes should offer a wide enough toe box that your toes are not pressed against one another.
  • Wear footwear that will protect your feet.
  • Be careful when moving heavy objects.
  • Try to avoid walking barefoot; this can make your toes and feet susceptible to injury or trauma.
  • Keep feet and nails clean and dry.
  • Always wear clean socks and shoes. Let shoes air out between uses.
  • Treat any nail problems during their early stages.
  • Talk with a podiatrist about additional prevention tips.

Talking to Your Doctor

Here are some questions you may want to ask your doctor about black toenails:

  • How likely is it that my black toenail will fall off and regrow without treatment?
  • Will my toenail change other colors while it is healing?
  • What other symptoms should I watch for that may indicate treatment is not working?
  • How long should I wait to contact you for a follow-up?
  • How long will it take for my nail to return to its normal shape and color?
  • Are there any options for cosmetic nails if my nail does not grow back the way I like?
  • What are the chances this problem recur?
  • Can I try to drain the blood at home?
  • Do I need to worry about anything malignant?
  • Is there any oral or topical medication that I can take or apply to the nail to prevent further discoloration?
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Medical References:

  1. American Medical Association "Family Medical Guide" 4th Edition (John Wiley & Sons, Inc. 2004) 1078
  2. M. Beers "Merck Manual of Medical Information" 2nd home edition (Pocket Books, 2003) 225
  3. Run Injury Free with Jeff Galloway, Training - Injury Archives - Black Toenail, http://www.jeffgalloway.com/training/injury_archives/black_toe.html
  4. Foot Health Facts, Black Toenails, http://www.foothealthfacts.org/what-is/black-toenails.htm

This page was last updated on April 27th, 2014



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