Understanding Black Toenails: Causes and Concerns

Think back to the last time you had a bruise—maybe on your arm, thigh, or elsewhere. You likely recognized that familiar black-and-blue patch right away. Bruises on the skin are common, but when discoloration appears under a toenail, it can be more concerning. Fortunately, in most cases, black toenails have simple, non-serious causes.

How Bruising Affects Your Toenails

Most black toenails result from bruising beneath the hard keratin of the nail. When you stub your toe, drop something heavy on it, or otherwise injure the tip of your toe, the impact can cause bleeding beneath the nail bed. This trapped blood stains the underside of the toenail, creating the darkened appearance. Depending on how much blood accumulates, the nail may or may not be painful.

If a significant amount of blood pools under the nail, it can create pressure, making it uncomfortable to wear shoes or participate in activities. While rare, a severely painful black toenail could indicate serious underlying damage, such as a nail bed injury or even a hidden fracture. In such cases, untreated wounds can increase the risk of infection.

Common Causes of Black Toenails

While a sudden injury—like stubbing your toe—can result in a black toenail, repetitive trauma is also a frequent culprit. Runners and athletes, in particular, are prone to toenail bruising from constant pressure and impact against the front of their shoes. Even ill-fitting footwear that’s too tight can cause repeated micro-injuries, leading to discoloration over time.

Recognizing the cause of a black toenail can help you determine whether it’s a minor issue or something that requires medical attention. When in doubt, consulting a specialist can provide peace of mind and ensure proper care.

When Black Toenails Aren’t Just Bruises

While bruising is the most common cause of black toenails, discoloration can sometimes stem from other underlying conditions. Though rare, certain fungal or mold infections can darken the keratin, and in very uncommon cases, a black toenail may indicate melanoma. Even though these serious conditions are unlikely, it’s always a good idea to have your toenails examined to rule out potential concerns.

Caring for Black Toenails

In many cases, black toenails are harmless and will resolve on their own as the nail grows out. However, if the discoloration is accompanied by pain, it may require treatment to relieve pressure and prevent complications.

At Next Step Foot & Ankle Clinic, Dr. Darren Silvester and our expert team will thoroughly examine your toenail and surrounding tissue for signs of infection, nail bed damage, or bone injuries. Based on our findings, we’ll recommend the best course of action.

For painless black toenails without complications, no immediate treatment may be necessary—the nail will simply grow out, or in some cases, it may detach naturally. If the nail does fall off, it’s important to protect the exposed skin from further damage.

For painful black toenails, where blood has pooled under the nail, a minor procedure can provide relief. Using a sterile needle, we’ll create a small opening in the nail to safely drain the trapped blood. The area will be thoroughly cleaned and treated to prevent infection. In rare cases, if there’s significant damage, the entire toenail may need to be removed to properly assess and treat any underlying lacerations or fractures.

Don’t Ignore Persistent Discoloration

While black toenails may be unsightly and uncomfortable, they are rarely dangerous with the right care. If you’re experiencing pain or prolonged discoloration, don’t wait for it to worsen—early treatment can prevent infections and more serious issues.

Let Dr. Darren Silvester and the team at Next Step Foot & Ankle Clinic help keep your feet healthy. Call us today at 210-375-3318 to schedule an appointment.