Redness in a toenail often signals an underlying issue affecting the nail unit, which is composed of the nail plate, the nail bed, and the nail matrix. The nail plate itself is translucent, meaning the pink color normally visible comes from the rich blood supply of the nail bed beneath it. When this area becomes red, it indicates either inflammation of the surrounding tissue or the accumulation of blood directly under the nail plate. Understanding the different causes of this symptom is the first step in determining the correct course of action.
Redness Caused by Physical Injury and Pressure
The most frequent cause of toe redness involves mechanical forces that directly injure the nail unit. A sharp, singular trauma, such as stubbing a toe or dropping a heavy object, can rupture the small blood vessels in the nail bed. This results in a subungual hematoma, which is an accumulation of blood trapped between the nail plate and the nail bed.
The presence of blood under the nail initially causes a dark red or purplish-black discoloration, often accompanied by throbbing pain due to the pressure buildup. This condition is sometimes called “runner’s toe” or “jogger’s toe” when it results from repetitive microtrauma, such as long-distance running or simply wearing shoes that are too tight. The repeated impact of the toe against the shoe’s toe box causes minor, cumulative damage.
While a small hematoma will usually resolve as the discolored nail grows out over several months, larger collections can cause the nail plate to separate from the nail bed. The redness in these instances is directly due to the visible pooled blood. The surrounding skin may also become red and inflamed from the initial injury or the resulting pressure.
Redness Due to Fungal and Bacterial Infections
Infections can cause redness by triggering an inflammatory response in the surrounding tissues. Acute paronychia, a common bacterial infection, typically presents as a rapid onset of intense redness, swelling, and pain localized to the nail folds, which are the skin borders around the sides and base of the nail. This localized inflammation is frequently caused by bacteria like Staphylococcus aureus entering a break in the skin barrier, often due to a minor trauma or an ingrown toenail.
In contrast, a fungal infection of the nail, known as onychomycosis, can cause a more chronic and diffuse redness. While a fungal infection itself often causes yellowish or cloudy discoloration of the nail plate, severe or long-standing cases can involve the nail bed. This involvement leads to chronic inflammation of the underlying tissue, which is sometimes visible through the nail plate as a persistent red or pink hue. This redness is the inflamed, highly vascularized nail bed shining through the nail.
Underlying Dermatological and Systemic Issues
Redness under the toenail can occasionally signal a non-infectious inflammatory skin condition or a systemic health problem. Nail psoriasis, an autoimmune condition, often affects the nail bed, producing a reddish-yellow discoloration called the “oil-drop” or “salmon patch” sign. This focal redness is caused by inflammation and localized fluid accumulation in the nail bed, shining through the nail plate. Psoriasis can also cause tiny red or dark lines called splinter hemorrhages, which are small areas of bleeding under the nail.
Another less common cause is lichen planus, a chronic inflammatory skin condition that can affect the nail matrix and nail bed. This inflammation can lead to a red appearance and can cause significant changes in the nail’s structure. Furthermore, red nail beds, particularly if they are consistently dark red or maroon, have been associated with certain systemic conditions, including heart disease.
When Red Toenails Warrant a Doctor’s Visit
While many causes of toenail redness are minor and resolve with simple care, several signs indicate the need for professional medical attention. Redness accompanied by severe or rapidly worsening pain, particularly if you cannot bear weight on the toe, should be evaluated. Signs of a spreading infection, such as red streaking extending up the foot, a foul odor, or the presence of pus, also require prompt care.
Individuals with chronic conditions like diabetes or poor circulation must seek immediate attention for any change in foot appearance, as these conditions significantly increase the risk of severe complications from seemingly minor infections. Finally, if the redness does not improve within a few weeks, or if it is associated with a change in the shape of the nail or the appearance of a dark streak that runs the length of the nail, consultation with a healthcare provider is recommended for an accurate diagnosis.