COVID-19 infection with SARS-CoV-2 is recognized for affecting various systems outside of the lungs, beyond the widely reported respiratory and flu-like symptoms. Among these non-respiratory effects are subjective neurosensory symptoms involving the skin. These uncomfortable sensations are often reported by patients during the acute illness or sometimes weeks or months later. The discomfort is not always tied to a visible rash, suggesting a direct involvement of the nervous system rather than just a surface skin reaction.
Specific Types of Skin Pain and Sensitivity
Patients experiencing this discomfort report distinct sensations that go beyond typical aches or surface irritation. One sensation is hyperesthesia, an abnormally increased sensitivity to touch. For individuals with this symptom, light contact, such as clothing brushing against the skin, can feel intensely painful or highly unpleasant. This extreme sensitivity is a hallmark of nerve involvement.
Another common symptom is paresthesia, often described as a prickling, tingling, crawling, or “pins and needles” feeling. This sensation frequently occurs without any external trigger and can affect the extremities or the trunk of the body. When the sensation is distinctly unpleasant, painful, or abnormal, it is categorized as dysesthesia. These feelings represent a malfunction in the way the body’s small sensory nerves transmit information to the brain.
How Inflammation Causes Nerve Involvement
The biological mechanism linking a viral infection to these nerve-related skin pains involves the body’s immune response. When SARS-CoV-2 enters the body, it triggers a systemic inflammatory reaction, including the release of signaling molecules known as cytokines. This heightened inflammation, sometimes called a “cytokine storm,” can damage tissues throughout the body, including the peripheral nervous system.
This inflammation is implicated in causing small fiber neuropathy (SFN), which is damage to the small, unmyelinated nerve endings located in the skin. These small fibers transmit pain, temperature, and touch sensations. When these delicate fibers become inflamed, damaged, or even lost, they begin to misfire, resulting in abnormal pain and sensitivity.
Histopathological studies show physical alterations in these nerve endings in patients with persistent skin symptoms. Researchers have observed both hypertrophy (an enlargement of nerve bundles) and nerve fiber loss depending on the disease stage. This damage provides a neuropathic basis for the reported dysesthesia and hyperesthesia. The disruption of these nerves’ normal function causes them to generate pain signals even in the absence of a harmful stimulus.
Acute Symptoms Versus Persistent Discomfort
The timeline of skin discomfort varies significantly among individuals who contract the virus. For some, neurosensory symptoms appear during the acute phase of the infection, often alongside fever, cough, and fatigue. This acute pain is transient, resolving within the span of the main illness, typically lasting just a few days to a couple of weeks. These symptoms are likely a temporary side effect of the systemic inflammation that characterizes the initial viral battle.
A different pattern emerges when the pain persists for weeks or months after the initial infection has cleared. This prolonged discomfort is recognized as a symptom of Post-acute sequelae of COVID-19 (PASC), commonly referred to as Long COVID. For those with PASC, the neuropathic pain is often linked to sustained small fiber neuropathy. Studies have found that approximately half of patients with painful Long COVID symptoms meet the diagnostic criteria for SFN.
This persistent skin pain can be debilitating, often occurring in cycles of flare-ups and temporary relief. The ongoing nature of this pain suggests a continued immune dysregulation or a slow recovery from the initial damage caused to the peripheral nervous system.
When to Seek Medical Guidance
While many skin symptoms are manageable, certain signs warrant professional medical attention. If the skin pain is severe enough to interfere with daily activities, sleep, or quality of life, consult a healthcare provider. They can help distinguish between different causes of pain and discuss treatments focused on neuropathic symptoms.
Seek immediate emergency care if skin changes are accompanied by signs of a severe systemic issue. These red flags include difficulty breathing, persistent chest pain, new confusion, or an inability to stay awake. Additionally, any change in skin, lips, or nail beds to a pale, gray, or blue color suggests a lack of oxygen and requires immediate attention.