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)
Bruised or blackened Toenail — Causes, Treatment, and Prevention
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 of blood and fluid not only causes the nail to become discolored, it also generates pressure, leading to intense pain.
In extreme injury 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 also 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). This is very rare.
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 as it can indicate injury to your nail bed.
How Are Black Toenails Diagnosed?
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 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.
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.
Can Black Toenails Be Prevented?
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.