When the valves in the leg veins weaken, blood and fluid collect in the lower legs. This raises pressure in the veins and causes leg swelling, a feeling of heaviness, and over time changes in the skin near the ankle. This is called chronic venous insufficiency.
If the pressure stays high, the skin can break down and form a venous ulcer: a shallow, often weeping wound, usually on the inner side of the ankle. These non-healing leg wounds can last for months unless the vein problem underneath is treated.
Leg swelling can also have other causes, such as heart, kidney or thyroid conditions, some medicines, or a clot in the leg. That is why a careful assessment matters.