A bruised toenail, medically known as a subungual hematoma, is a common injury resulting in noticeable discoloration and sharp discomfort. This condition involves a collection of blood beneath the nail plate. While the sight of a dark, discolored toenail can be alarming, most cases are not serious and resolve with time and simple care.
What Exactly is a Bruised Toenail?
A subungual hematoma is the result of trauma causing small blood vessels in the nail bed to rupture and bleed. The nail bed is the soft tissue directly beneath the nail plate, and it is rich in nerve endings and blood supply. When bleeding occurs in this area, the blood becomes trapped because the rigid nail plate prevents it from escaping.
This confinement of blood creates a buildup of pressure between the nail bed and the nail plate. This pressure is the direct cause of the intense, throbbing pain associated with the injury. The pooling of blood is what gives the nail its distinct bruised appearance, which can change color over time.
Common Causes and Identifying Symptoms
Bruised toenails generally arise from two main categories of forces: acute trauma and repetitive microtrauma. Acute trauma involves a single, forceful event, such as stubbing a toe hard against furniture or dropping a heavy object directly onto the nail. These incidents cause immediate and significant damage to the underlying blood vessels.
Repetitive microtrauma is a common cause, especially for runners and athletes. This happens when the toe repeatedly slides forward and jams against the inside of a shoe’s toe box, often due to ill-fitting footwear or long-distance activity like hiking or running downhill. The constant, minor impact eventually damages the nail bed, leading to a slow bleed and hematoma formation.
The primary symptom is immediate and often severe throbbing pain that is directly proportional to the amount of pressure under the nail. Visible discoloration develops as the blood pools, typically starting as a red or purplish hue and then darkening to brown or black within a few hours as the blood coagulates and breaks down. The discoloration will remain until the damaged section of the nail grows out, which can take several months.
Treatment Options and When to See a Doctor
For minor subungual hematomas that cause little pain and cover less than 25% of the nail, treatment focuses on relieving discomfort and supporting healing. Immediately applying the R.I.C.E. protocol—Rest, Ice, Compression, and Elevation—can help limit swelling and bleeding beneath the nail. Over-the-counter pain relievers, such as acetaminophen or ibuprofen, may also be used to manage the pain.
If the pain is severe or the hematoma covers a significant portion of the nail, medical intervention may be necessary to relieve pressure. This procedure, called trephination, involves a healthcare professional creating a small, sterile hole through the nail plate to allow the trapped blood to drain. Drainage provides instant relief from the intense pressure and throbbing pain.
You should seek immediate medical attention if you suspect the injury is more than a simple bruise. Signs that warrant a doctor’s visit include:
- Blood pooling that covers more than 50% of the nail plate.
- Suspected underlying fracture to the toe bone, which usually causes significant difficulty bearing weight.
- Signs of infection, such as increasing redness, warmth, or pus draining from the nail edges.
- Red streaks extending up the foot.
In cases where the pressure is not relieved, the pooled blood can cause the nail plate to lift and eventually detach from the nail bed. A new, healthy nail will eventually grow in its place, though the complete regrowth process for a toenail can take up to a year. Monitoring is encouraged to ensure the new nail grows properly and that no long-term damage occurred to the nail matrix.