What Causes Swelling in the Legs and Feet?

Leg and foot edema refers to the abnormal accumulation of excess body fluid in the interstitial spaces outside the blood vessels of the lower legs, resulting in tissue swelling. Affected tissues exhibit increased volume and pallor; microscopically, edematous fluid is observed accumulating between cells and fibrous connective tissue or within tissue cavities. Common types of leg and foot edema include: (1) the “flabby-leg” type—associated with sedentary lifestyle and poor muscular endurance; (2) the “elephant-leg” type—characterized by excessive subcutaneous fat in the legs and increased sweating; and (3) the “radish-leg” type—marked by well-developed calf gastrocnemius muscles and a tendency toward psychological tension. So, what causes leg and foot edema? The following section addresses this question.

Causes of Leg and Foot Edema

1. Venous Inflammation (Phlebitis)

Venous inflammation and heart failure are common contributors to chronic leg swelling. Clinically, phlebitis typically causes unilateral leg swelling, whereas congestive heart failure usually results in bilateral edema. Moreover, phlebitis is often accompanied by pain, while edema due to heart failure is generally painless. Different underlying diseases causing leg swelling have distinct pathophysiological mechanisms and clinical features. Severe hypothyroidism may also lead to generalized edema—including in the legs and feet.

2. Liver Failure

Patients with liver failure frequently develop hypoalbuminemia. This condition commonly manifests as edema in the lower legs and feet—and may even progress to generalized edema. Additionally, in cirrhosis, structural damage to the liver impedes portal venous return, elevating portal pressure; combined with hypoalbuminemia secondary to hepatic insufficiency, these factors contribute significantly to leg edema. Certain medications—including amlodipine and nifedipine—may also induce peripheral edema.

3. Kidney Failure

This is especially relevant in patients with uremia, where impaired urinary excretion leads to fluid retention in interstitial tissues—resulting in edema of the lower legs and feet. Similarly, acute glomerulonephritis, chronic glomerulonephritis, or nephrotic syndrome can reduce renal blood flow, cause sodium and water retention, increase capillary permeability, and promote excessive urinary protein loss. These changes lower plasma colloid osmotic pressure, thereby promoting interstitial fluid accumulation and subsequent leg edema.

The above outlines the primary causes of leg and foot edema. We hope this information is helpful to you.