A subungual hematoma is the medical term for the dark, throbbing spot beneath a nail. This condition occurs when blunt or crush trauma damages blood vessels in the nail bed, causing blood to pool and become trapped beneath the hard nail plate. The resulting pressure causes intense pain and dark discoloration, ranging from red-purple to black. Essentially, this is a deep bruise under the nail, and the dried blood remains visible because it has no pathway to escape the sealed area.
How the Body Naturally Resolves Subungual Hematomas
If the injury is minor and no active intervention is taken, the body will eventually resolve the subungual hematoma through nail growth. The dried blood does not dissolve or get reabsorbed like a bruise on the skin; instead, it remains adhered to the nail bed as a solid mass.
Over time, the new, healthy nail forms at the base and pushes the entire old nail plate forward. This slow, continuous growth physically ejects the discolored section, moving the hematoma toward the free edge until it is fully grown out. The resolution timeline depends on the rate of nail growth, which is significantly slower for toes than for fingers. A fingernail typically takes about four to six months to be completely replaced, while a toenail can take a year or longer.
Safe Techniques for Home Drainage
For minor injuries causing significant, throbbing pain, relieving pressure through a process called trephination can provide immediate relief. This must be done with extreme caution. Before attempting home drainage, ensure the injury is recent (less than 48 hours old) and the nail plate is intact. Individuals with diabetes, poor circulation, or a compromised immune system should never attempt this due to the high risk of severe infection.
The safest home method involves using heat to melt a small hole through the nail plate, preventing the introduction of bacteria or physical damage to the nail bed.
- Straighten a metal paperclip and hold one end with a cloth for protection.
- Heat the tip of the paperclip in a flame until it glows red-hot, which effectively sterilizes the instrument.
- Gently touch the hot tip directly onto the center of the dark hematoma on the nail surface. Do not push or apply pressure, as the heat alone will melt through the hard keratin.
- Reheat the paperclip as needed until a small hole is created and the trapped blood begins to ooze out.
Because the nail contains no nerves, this process should not cause pain. Once the pressure is released and the blood drains, clean the area and soak the finger or toe in warm, soapy water two to three times a day for a few days to encourage continued drainage.
Critical Signs Requiring Immediate Medical Attention
While many subungual hematomas are minor, certain signs indicate the injury is more severe and requires immediate medical evaluation. If the throbbing pain does not subside immediately after successful drainage, this suggests a more serious underlying issue, such as a fracture of the fingertip bone (distal phalanx). An X-ray is often necessary to rule out an associated bone break, which requires specific medical management.
Any signs of infection necessitate immediate care, as bacteria can enter the nail bed through the site of injury or drainage. These signs include increasing redness, swelling, or warmth around the nail, the presence of pus draining from the area, or red streaks extending up the finger or toe. A fever is also a systemic sign of a spreading infection that requires prompt treatment.
If the hematoma covers more than 50% of the entire nail surface, it increases the probability of a deep laceration to the underlying nail bed. In these cases, a medical professional may need to remove the nail plate entirely to repair the nail bed with stitches. This repair helps prevent permanent deformity or splitting of the new nail as it grows in.