A bruised toenail, or subungual hematoma, occurs when blood collects underneath the toenail. It results from an injury that causes blood vessels in the nail bed to break and leak. The trapped blood creates discoloration and can lead to swelling and pain beneath the rigid nail. While often not serious, a subungual hematoma can be painful due to pressure buildup in the confined space.
Visual Signs of a Bruised Toenail
A bruised toenail displays distinct color changes that evolve. Initially, the area under the nail might appear red or purplish, indicating fresh blood. As the blood clots and breaks down, the discoloration often progresses to dark brown or black, giving the appearance of a “black toenail.” The bruise can manifest as a small, localized spot, a streak, or cover a significant portion of the nail, depending on the extent of the injury.
Along with the visual changes, a bruised toenail can cause physical sensations such as pressure or throbbing pain beneath the nail. This pain arises from the blood accumulating in the restricted space. Over weeks to months, as the toenail grows, the discolored area will gradually move forward with the nail, eventually growing out and being trimmed away. For the big toe, this regrowth can take six to eight months, and sometimes over a year, while other toes may heal within three months.
Understanding the Causes
A bruised toenail results from trauma or repetitive stress to the toe. Direct trauma, such as dropping a heavy object on the foot, stubbing a toe forcefully, or kicking something hard, can cause immediate bleeding under the nail. These impacts rupture blood vessels in the nail bed, leading to blood pooling in the confined space. This trapped blood creates pressure and the characteristic discoloration.
Repetitive microtrauma is another common cause, often seen in athletes or individuals wearing ill-fitting footwear. Activities like long-distance running, hiking, or sports involving sudden stops and starts can cause the toes to repeatedly hit the inside of a shoe. Shoes that are too tight, too loose, or have a low toe box can also contribute to this repeated pressure, injuring the nail bed over time. This consistent friction and impact lead to small vessels breaking, resulting in a subungual hematoma.
When Professional Help is Needed
While many bruised toenails resolve on their own, certain indicators suggest professional medical evaluation. Severe, throbbing pain that is not relieved by elevation and ice, or pain that persists for several days, warrants a doctor’s visit. Signs of infection, such as increased redness, swelling, warmth around the nail, or the presence of pus or discharge, require immediate attention. Furthermore, if the nail separates from the nail bed, if there is suspicion of a broken toe bone, or if the bruise covers more than half of the nail, medical assessment is advisable. Any new or unexplained dark streaks or discoloration under the nail that doesn’t appear related to an injury should also be checked.