Water retention, medically known as edema, is the buildup of excess fluid within the body’s tissues, often manifesting as noticeable swelling in the hands, ankles, and feet. This occurs when fluid leaks out of the capillaries and accumulates in the surrounding spaces. Many patients recovering from a COVID-19 infection report developing this swelling, either during the acute phase of illness or in the weeks following recovery. The connection between SARS-CoV-2 infection and fluid imbalance is a reported side effect.
How the Virus Affects Fluid Balance
The physiological reasons for fluid retention during or after a COVID-19 infection are complex, involving both the body’s reaction to the virus and the effects of common treatments. One primary mechanism is the widespread systemic inflammation triggered by the immune system’s response to the SARS-CoV-2 virus. Severe infection can lead to a “cytokine storm,” where an excessive release of signaling proteins called cytokines causes damage to the inner lining of blood vessels, known as the endothelium.
This damage increases the permeability of the blood vessel walls, allowing fluid and proteins to leak out of the circulation and into the interstitial tissues. This vascular leakage contributes to pulmonary edema (fluid in the lungs), which is a major cause of respiratory distress in severe COVID-19 cases. Endothelial dysfunction and the resulting inflammation can also contribute to the formation of microthrombi and blood clots, further disrupting normal fluid dynamics.
Another potential factor is the virus’s interaction with the Renin-Angiotensin-Aldosterone System (RAAS), a hormonal pathway that regulates blood pressure and fluid balance. SARS-CoV-2 uses the Angiotensin-Converting Enzyme 2 (ACE2) receptor to enter cells, and this binding can lead to a reduction in ACE2 activity. The resulting imbalance can cause an overactivation of the RAAS, leading to increased levels of Angiotensin II, which promotes vasoconstriction, inflammation, and the retention of sodium and water by the kidneys. This dysregulation contributes to an increase in intravascular fluid volume and can worsen edema.
Beyond the direct effects of the virus, fluid retention is commonly caused by the use of corticosteroids, such as Dexamethasone, to treat severe COVID-19. These powerful anti-inflammatory medications suppress the hyperactive immune response in hospitalized patients requiring oxygen. Corticosteroids induce sodium and water retention, which can transiently increase blood pressure and fluid volume. This medication-induced fluid accumulation is distinct from viral mechanisms, but both contribute to the overall experience of swelling.
Recognizing Symptoms That Require Medical Care
While mild, generalized swelling is often a temporary side effect of illness or medication, certain symptoms related to fluid retention signal a serious medical issue requiring immediate attention. One significant concern is deep vein thrombosis (DVT), a blood clot in the leg. Signs of a DVT include throbbing or cramping pain in one leg, usually in the calf or thigh, accompanied by swelling only in that single leg. The affected area may also feel warm to the touch and appear red or darkened.
Fluid retention can also be a symptom of potential heart complications, which are known to occur after a COVID-19 infection. If edema is accompanied by sudden, unexplained weight gain over a few days or weeks, it may suggest the heart is not pumping efficiently, causing blood to pool in the lower body. Other accompanying warning signs include shortness of breath, chest pain that worsens with breathing, or a fluttering heartbeat.
A blood clot that travels from the leg to the lungs is called a pulmonary embolism (PE). If you experience swelling and pain along with sudden breathlessness, sharp chest pain, or coughing up blood, seek emergency medical care immediately. Any severe or uneven swelling, or edema paired with confusion or profound fatigue, warrants a prompt consultation with a healthcare provider to rule out serious underlying causes.
Home Strategies for Reducing Edema
For mild, generalized fluid retention not accompanied by severe warning signs, several practical home strategies can help manage the swelling. Using gravity involves elevating the affected limbs, such as the feet and ankles. Resting with your legs positioned above the level of your heart helps drain excess fluid out of the tissues and back toward the central circulation.
Movement is also beneficial, as moderate exercise helps the circulatory system work properly to guide fluid toward the lymphatic and urinary tracts for excretion. Even gentle activity can prevent fluid from settling in the extremities, especially after long periods of sitting or standing. Wearing compression garments, such as support stockings or socks, can help by applying pressure to the limbs, which improves blood flow and prevents the buildup of fluid.
Dietary adjustments can play a significant role, particularly by reducing the intake of sodium, which is directly linked to fluid retention. Opting for fresh foods over packaged or processed items, which often contain hidden salt, can make a difference. Increasing consumption of potassium-rich foods, such as bananas and watermelons, can also help by lowering sodium levels in the body.
Finally, counterintuitively, drinking more water helps reduce water retention, as a well-hydrated body is less likely to hold onto excess fluid. Adequate hydration helps the body flush out excess salt and waste more efficiently. Focus on water and avoid dehydrating beverages like alcohol and excessive amounts of coffee.