A bruised toenail, often resulting from an injury like stubbing your toe or dropping a heavy object, raises the question of whether the nail will be lost. While nail loss is a possibility, it is not guaranteed and depends entirely on the severity of the initial trauma. This article explains the biological process of a bruised toenail and the factors that determine its fate.
The Mechanism of a Subungual Hematoma
The medical term for a bruised nail is a subungual hematoma, meaning a collection of blood beneath the nail. This condition occurs when blunt force trauma ruptures small blood vessels located in the nail bed, the soft tissue directly underneath the nail plate. Because the hard nail plate is tightly secured, the resulting blood has no place to drain.
The trapped blood pools in the confined space between the nail plate and the nail bed, leading to the characteristic blue, purple, or black discoloration. This accumulation causes significant pressure to build up, which often results in intense, throbbing pain immediately after the injury. The nail plate itself does not bruise; the color you see is dried blood lodged beneath it.
Factors That Determine Nail Detachment
Nail detachment primarily depends on the volume of trapped blood and the pressure it creates. A small, painless hematoma covering less than 25% of the nail area is unlikely to result in detachment and will simply grow out with the nail over time. The pooled blood in these minor cases is reabsorbed by the body.
Detachment, known medically as onycholysis, becomes probable when the hematoma covers 50% or more of the nail. The significant volume of blood physically separates the nail plate from the underlying nail bed, disrupting the strong connection. This separation prevents the nail from receiving the nutrients it needs to remain adhered.
The process of the old nail falling off is a natural, slow mechanism driven by new growth. As the nail matrix—the tissue at the base of the toe responsible for growth—continues to produce a healthy, new nail, this growth pushes the damaged, separated old nail forward. This can take several weeks or months, and the old nail will eventually detach on its own. It is important not to pull the loosened nail off prematurely, as this can damage the healing nail bed underneath.
Immediate Care and Signs Requiring Professional Attention
For a mildly bruised toenail without severe, throbbing pain, immediate care focuses on managing discomfort and swelling. Applying the R.I.C.E. protocol—Rest, Ice, Compression, and Elevation—helps reduce initial inflammation and pain. Over-the-counter pain relievers can also be used to manage tenderness.
If the pain is severe and throbbing, it signals excessive pressure that may require professional attention. A healthcare provider can perform trephination, which involves making a small hole in the nail plate to drain the trapped blood and relieve pressure. This procedure is most effective when performed within 24 to 48 hours of the injury. Never attempt to drain a subungual hematoma at home, as this introduces a significant risk of infection.
Seek immediate professional medical care if you notice signs of infection, such as increasing redness, warmth, swelling around the nail, or the presence of pus. If the trauma was severe, an X-ray may be needed to rule out a fracture of the underlying toe bone, which is common with crush injuries. If the nail is lost, a full toenail typically takes 12 to 18 months to be completely replaced.