Subungual Hematoma: Understanding the ‘Black Nail’ After Trauma

Shivendra Pratap Singh


High Court Lucknow

Medico Legal

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Published on: 13 Aug, 2023

A subungual hematoma refers to the accumulation of blood beneath a toenail or fingernail (nail bed). Often referred to colloquially as a “black nail,” it is usually the result of trauma to the nail. This injury can be extremely painful due to the pressure build-up from blood collection in a confined space. This article will explore the causes, symptoms, treatments, and prevention of subungual hematomas.

1. Causes of Subungual Hematoma:

  • Direct Trauma: This is the most common cause. It can result from incidents like stubbing your toe, dropping an object on your finger, or shutting your finger in a door.
  • Repetitive Trauma: Frequently seen in runners or athletes, this can occur from shoes that don’t fit properly or prolonged repetitive activities.

2. Symptoms:

  • Discoloration: The nail appears blue-black due to blood beneath it.
  • Pain: This results from the pressure of the accumulated blood.
  • Swelling: The affected finger or toe may swell.

3. Diagnosis:

A subungual hematoma is typically diagnosed through a visual inspection. If the injury is severe or if a fracture is suspected, an X-ray might be performed.

4. Treatment Options:

  • Drainage (Trephination): For larger or more painful hematomas, a doctor may decide to release the pressure by drilling a small hole in the nail. This allows the pooled blood to drain out and provides instant pain relief.
  • Pain Relief: Over-the-counter pain relievers may be recommended.
  • Observation: If the hematoma is small and not causing significant pain, it may be left to heal on its own.
  • Nail Removal: In cases of a severely damaged nail or underlying nail bed, the entire nail might be removed to facilitate treatment and healing.
  • Antibiotics: These might be prescribed if there’s an associated risk or indication of infection.

5. Potential Complications:

  • Nail Deformity: The nail might grow back with a deformity or may not grow back at all.
  • Infection: If not treated or if the skin under the nail is torn, there’s a risk of infection.
  • Fracture: Sometimes, the trauma might result in a fracture of the bone beneath the nail.

6. Prevention:

  • Wear Protective Footwear: Especially in environments where toe injuries are common.
  • Careful Handling: Exercise caution with doors, heavy objects, and tools.
  • Proper Shoe Fit: For athletes and runners, ensuring shoes fit properly and are appropriate for the activity can help in preventing repetitive trauma.


A subungual hematoma, though a seemingly minor injury, can be significantly painful and disruptive. While most cases can be easily treated and heal without complications, it’s essential to be aware of the symptoms and seek medical attention if the pain is severe or if there are signs of infection. Prevention, as always, remains the best approach, emphasizing the importance of caution and protective measures in our daily activities.


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