A bruised toenail, medically termed a subungual hematoma, occurs when blood collects underneath the nail plate. This condition arises from trauma to the toe, causing blood vessels in the nail bed to rupture and leak blood into the confined space beneath the nail. It can affect individuals of all ages, often appearing as a dark discoloration (reddish-purple to black) under the nail.
Common Causes from Impact and Pressure
Direct trauma is a common cause of bruised toenails. This can happen when a heavy object falls onto the toe, such as a dropped dumbbell, or when the toe is severely stubbed against a hard surface. Impacts can crush the nail or nail bed, leading to immediate bleeding and dark discoloration under the nail. The pressure from the accumulating blood can cause intense, throbbing pain.
Repetitive pressure also contributes to bruised toenails, particularly in active individuals. Ill-fitting footwear, whether too tight or too loose, allows the foot to slide and jam against the shoe’s toe box, causing repeated micro-trauma. Activities like long-distance running, hiking, or sports involving sudden stops and starts, such as tennis or soccer, can exert continuous pressure on the toes, leading to blood vessel damage and bruising over time. Downhill running, in particular, increases injury likelihood due to forward force on the toes.
Other Contributing Issues
Beyond direct impacts and repetitive pressure, other factors can lead to bruised toenails or conditions that resemble them. Fungal infections, known as onychomycosis, can weaken the nail structure, making it more prone to injury and bruising. They can also cause discoloration (often yellow, brown, or white) that might be mistaken for a bruise. However, unlike a bruise, a fungal infection usually presents with thickening, crumbling, or a distorted nail shape, and typically lacks immediate pain.
Underlying medical conditions or medications can increase bruising susceptibility. Conditions affecting blood clotting, such as coagulopathy, or anticoagulant medications (blood thinners) can make individuals more prone to bleeding under the nail even from minor trauma. Skin conditions like psoriasis can affect the nail bed, causing discoloration, pitting, or separation of the nail, sometimes confused with a subungual hematoma. Improper nail care, such as not trimming nails correctly, can also increase the risk of repetitive trauma, especially when wearing tight footwear.
When to Consult a Doctor
While many bruised toenails heal without medical intervention, certain signs warrant professional attention. Intense or worsening pain, or pain that persists for more than a few days, suggests evaluation, as it could indicate a more serious injury or infection. If there is any pus, increased redness, warmth, or fever around the nail, these indicate a possible infection, requiring prompt treatment to prevent complications.
If the nail is significantly lifting, detaching from the nail bed, or if the bruise covers more than 25% to 50% of the nail, consult a healthcare provider. These situations can indicate underlying nail bed damage or a bone fracture, possibly requiring blood drainage or other interventions. If a bruise appears without any known trauma, or if there is a linear streak or stripe of discoloration along the nail, seek medical advice to rule out serious underlying issues, such as a subungual melanoma. Individuals with diabetes, peripheral vascular disease, or compromised immune systems should consult a doctor immediately for any toenail injury due to increased risk of delayed healing and complications.