A bruise under a toenail, medically termed a subungual hematoma, occurs when blood becomes trapped beneath the nail plate. This condition typically results from an injury that causes small blood vessels in the nail bed to rupture. The accumulation of blood creates discoloration, often appearing as a red, purple, or black mark visible through the nail.
Common Causes
Subungual hematomas frequently arise from direct trauma to the toe. This can happen if a heavy object is dropped directly onto the toenail, or if the toe is forcefully stubbed against a hard surface. Such impacts generate significant pressure, causing the capillaries beneath the nail to break and release blood.
Another common pathway for developing a bruise under the toenail involves repetitive microtrauma. Activities like long-distance running, hiking, or even extended periods of walking can cause the toes to repeatedly hit the inside of footwear. Ill-fitting shoes, whether too tight or too loose, exacerbate this by either pressing directly on the nail or allowing the foot to slide forward, causing constant friction and pressure. Over time, these repeated impacts can cumulatively damage the nail bed, leading to blood collection.
The Healing Process and Timeline
Initially, the bruise may appear red, progressing to a darker purple or black as the blood clots and deoxygenates. Since the nail plate is a hard, protective layer, the discolored blood cannot dissipate or be reabsorbed quickly like a bruise on the skin.
Healing occurs as the toenail grows out, gradually pushing the discolored blood forward and off the nail bed. The rate depends on the size of the hematoma and an individual’s nail growth speed. Smaller bruises are less noticeable as they grow out, while larger ones remain visible for an extended period.
A typical toenail grows at a rate of approximately 1 to 2 millimeters per month. Given this slow growth, it can take several months for the discolored area to migrate from the base to the tip of the nail. Complete resolution, where the affected nail is replaced by new, healthy growth, often spans 6 to 9 months, and in some cases, it may take up to a full year, especially if the bruise is extensive or near the nail’s base. Occasionally, pressure from the hematoma or underlying injury can cause the old, discolored nail to detach. A new, healthy nail will grow in its place, provided the nail matrix (the tissue responsible for nail growth) was not permanently damaged.
When to Seek Medical Attention
While many subungual hematomas resolve on their own, certain signs warrant medical evaluation. Persistent or severe throbbing pain indicates significant pressure from blood. A healthcare professional may perform trephination, creating a small hole in the nail to relieve pressure and drain blood, providing immediate pain relief.
Signs of infection around the nail, such as increasing redness, swelling, warmth, pus, or red streaks, require prompt medical attention. These symptoms suggest a bacterial infection requiring antibiotic treatment. If the nail is significantly lifted or completely separates, consult a doctor for proper healing and to prevent complications. Additionally, if the bruise appeared without clear trauma, or if the injury was severe enough to suspect a bone fracture, seek medical advice for accurate diagnosis and management.
A bruise under a toenail, medically termed a subungual hematoma, occurs when blood becomes trapped beneath the nail plate. This condition typically results from an injury that causes small blood vessels in the nail bed to rupture. The accumulation of blood creates discoloration, often appearing as a red, purple, or black mark visible through the nail.
Common Causes
Subungual hematomas frequently arise from direct trauma to the toe. This can happen if a heavy object is dropped directly onto the toenail, or if the toe is forcefully stubbed against a hard surface. Such impacts generate significant pressure, causing the capillaries beneath the nail to break and release blood.
Another common pathway for developing a bruise under the toenail involves repetitive microtrauma. Activities like long-distance running, hiking, or even extended periods of walking can cause the toes to repeatedly hit the inside of footwear. Ill-fitting shoes, whether too tight or too loose, exacerbate this by either pressing directly on the nail or allowing the foot to slide forward, causing constant friction and pressure. Over time, these repeated impacts can cumulatively damage the nail bed, leading to blood collection.
The Healing Process and Timeline
Initially, the bruise may appear red or purple, progressing to a darker brown or black as the blood clots and deoxygenates. Since the nail plate is a hard, protective layer, the discolored blood cannot dissipate or be reabsorbed quickly like a bruise on the skin.
Healing occurs as the toenail grows out, gradually pushing the discolored blood forward and off the nail bed. The rate depends on the size of the hematoma and an individual’s nail growth speed. Smaller bruises are less noticeable as they grow out, while larger ones remain visible for an extended period.
A typical toenail grows at an average rate of about 1.62 millimeters per month. Given this slow growth, it can take several months for the discolored area to migrate from the base to the tip of the nail. Complete resolution, where the affected nail is replaced by new, healthy growth, often spans 6 to 9 months, and in some cases, it may take up to a full year or even 18 months, especially if the bruise is extensive or near the nail’s base. Occasionally, pressure from the hematoma or underlying injury can cause the old, discolored nail to detach. A new, healthy nail will grow in its place, provided the nail matrix (the tissue responsible for nail growth) was not permanently damaged.
When to Seek Medical Attention
While many subungual hematomas resolve on their own, certain signs warrant medical evaluation. Persistent or severe throbbing pain indicates significant pressure from trapped blood. A healthcare professional may perform trephination, creating a small hole in the nail to relieve pressure and drain blood, providing immediate pain relief.
Signs of infection around the nail, such as increasing redness, swelling, warmth, pus, or red streaks, require prompt medical attention. These symptoms suggest a bacterial infection requiring antibiotic treatment. If the nail is significantly lifted or completely separates, consult a doctor for proper healing and to prevent complications. Additionally, if the bruise appeared without clear trauma, or if the injury was severe enough to suspect a bone fracture, seek medical advice for accurate diagnosis and management.