Swollen ankles? This is how fluid gets trapped in your legs.

Why do your ankles actually swell?

Swollen ankles usually occur when blood vessels in the legs aren't functioning optimally. This reduces blood flow back to your heart, causing increased pressure in your legs. This causes fluid to leak through the blood vessel walls and accumulate in the tissues.

These are the main culprits:

1. Weakened veins and valves

When the walls of your veins become weaker or the valves no longer close properly, too much blood remains in your legs. The increasing pressure pushes fluid into the tissues, especially as the day progresses. This is by far the most common reason for persistent swelling.

2. Lack of exercise or staying in the same position for a long time

Your calf muscles function as a natural pump that pumps blood upward. But if you don't move much or sit or stand in the same position for hours, that calf muscle pump doesn't function properly, and fluid retention is easier.

3. A thrombosis in the past

A past experiencethrombosisCan damage the valves in your veins. The result: less efficient blood flow and faster fluid retention.

4. Varicose veins

Stretched, weakened veins cause blood to flow backward. This increased pressure in your lower leg leads to heavy, swollen legs and visible varicose veins.

5. Heat and tight clothing

In warm weather, blood vessels expand, allowing fluid to escape more easily. Tight socks or pants can further restrict circulation and increase swelling.