Warts are benign skin growths caused by infection with the human papillomavirus (HPV), which stimulates the skin cells to multiply rapidly. When a wart begins to darken, it usually means that the virus-infected tissue is undergoing a process of destruction, whether due to an external treatment or the body’s own immune response. This discoloration is a frequent observation and should be understood as a sign of progress rather than a complication.
The Expected Outcome: Necrosis and Dying Tissue
Treatment Success and Necrosis
The most common reason a wart turns black is a successful result of a removal treatment, such as cryotherapy (freezing) or the application of strong chemicals like salicylic acid. These methods are designed to destroy the wart tissue by cutting off its necessary resources. The blackening signifies the onset of necrosis, which is the death of the wart cells.
Vascular Damage
When liquid nitrogen is used, the extreme cold causes damage to the cells and the tiny blood vessels that feed the wart. This vascular damage leads to a localized loss of blood supply, effectively starving the virus-infected tissue. The resulting black color is simply a mass of dead tissue that the body is preparing to shed.
The Role of Blood: Thrombosis and Trauma
Black spots can also appear in a wart without any recent treatment, stemming from the wart’s inherent structure. Warts are highly vascular, containing many small, fragile capillary loops that grow upward into the tissue. The wart’s rapid growth and the pressure exerted upon it, especially in plantar warts on the foot, can easily cause these delicate vessels to rupture.
Minor trauma, such as walking, friction, or scraping, can lead to internal bleeding within the wart’s rough, thickened layers. This results in thrombosis, or the clotting of blood within the capillaries, which appears as small, dark specks. These visible black dots are often mistaken for “wart seeds,” but they are actually tiny, dried blood clots trapped inside the tissue.
Following the Blackening: What to Expect Next
Following the blackening, the dead tissue initiates the process of sloughing. The blackened area will begin to dry out, harden, and form a scab-like crust over the following days to weeks.
Picking at or forcefully removing the black crust can lead to bleeding, infection, potential scarring, or may even allow the virus to spread to surrounding skin. Keep the area clean and protected, perhaps with a simple bandage or a thin layer of petroleum jelly, until the dead tissue eventually peels or falls away on its own. The underlying skin may appear pink and sensitive for a short time before fully healing.
When Black Is Not Normal: Signs for Medical Concern
While blackening is often a good sign, certain accompanying symptoms or characteristics warrant prompt medical evaluation. Signs of a secondary bacterial infection include severe and increasing pain, spreading redness that extends beyond the wart’s border, significant swelling, or the presence of pus or a foul-smelling discharge.
Medical attention is also necessary if the black spot exhibits features that are irregular or rapidly changing, which could suggest a different skin condition. These characteristics include an asymmetrical shape, irregular or poorly defined borders, or a rapid change in size or color beyond the expected darkening. If a new black spot appears spontaneously without any prior treatment or obvious trauma, consulting a healthcare professional is the correct measure to ensure an accurate diagnosis.