Leg swelling, medically known as edema, occurs when excess fluid accumulates in the body’s tissues, typically causing puffiness in the ankles, feet, or legs. This fluid buildup can make the affected area appear larger, feel heavy, or even leave temporary indentations when pressed. While edema can arise from various factors, understanding its connection to infections like COVID-19 is important for public health.
Is Leg Swelling a Direct COVID Symptom?
Leg swelling is generally not a primary or common symptom of acute COVID-19 infection, unlike fever, cough, or fatigue. While some individuals with COVID-19 have reported leg swelling, it is usually not the initial or most prominent sign. Instead, when leg swelling occurs in the context of COVID-19, it often points to underlying complications or related conditions that the infection can trigger or worsen.
How COVID-19 Can Lead to Swelling
COVID-19 can indirectly cause leg swelling through several physiological mechanisms, primarily driven by the body’s immune response. The infection often leads to systemic inflammation, which increases vascular permeability. This means blood vessels become “leakier” and allow fluid to escape from the bloodstream into surrounding tissues, contributing to edema. In severe cases, COVID-19 can trigger an exaggerated immune response known as a “cytokine storm,” where the body releases an overabundance of inflammatory proteins. This intense inflammation further exacerbates vascular permeability, leading to more significant fluid retention and swelling. Additionally, severe illness and prolonged immobility, common during hospitalization for COVID-19, can also contribute to fluid pooling in the legs and subsequent swelling.
Related Conditions Causing Leg Swelling
Leg swelling in individuals with COVID-19 can be a sign of specific, more serious medical conditions. One significant concern is Deep Vein Thrombosis (DVT), where blood clots form in the deep veins, most commonly in the legs. COVID-19 increases the risk of blood clot formation due to inflammation, altered blood coagulation, and reduced mobility. DVT typically causes swelling, pain, warmth, and redness in only one leg.
COVID-19 can also affect the heart, leading to impaired pumping function and fluid buildup throughout the body, including the legs. Conditions such as myocarditis (inflammation of the heart muscle) or stress cardiomyopathy can result from the infection, causing bilateral leg swelling. When the heart cannot pump blood efficiently, fluid can accumulate.
Kidney complications are another potential cause of leg swelling following COVID-19. Severe COVID-19 can sometimes lead to acute kidney injury, where the kidneys’ ability to filter fluids and waste from the blood is compromised. This impairment can result in generalized fluid retention, often manifesting as swelling in the legs, ankles, or feet.
Some individuals with “Long COVID” or Post-Acute Sequelae of COVID-19 (PASC) also report persistent or new-onset leg swelling. While the exact mechanisms for this prolonged symptom are still under investigation, it may involve ongoing inflammation, microclots, or autonomic nervous system dysfunction.
When to Seek Medical Care
It is important to seek medical attention for leg swelling, especially if it occurs in conjunction with a recent or current COVID-19 infection. Certain signs indicate a potentially serious underlying condition that requires prompt evaluation. Seek immediate medical care if the leg swelling appears suddenly. Specific warning signs include swelling in only one leg, especially if accompanied by pain, tenderness, warmth, or redness, as this could indicate a deep vein thrombosis. If leg swelling is accompanied by symptoms such as chest pain, difficulty breathing, shortness of breath, dizziness, or coughing up blood, it could signal a more severe condition like a blood clot in the lungs or a serious heart issue. Always consult a healthcare professional for proper diagnosis and guidance.