Causes of Leg Swelling from Knee to Ankle

The pattern matters: swelling in both legs often has a different explanation from sudden swelling in one leg. Note when it began, whether the skin is hot or red, and whether it improves after resting with the leg raised.

Fluid can collect in the tissues after long periods of standing or sitting, during pregnancy, or when the veins do not return blood efficiently. Varicose veins can contribute to ankle and lower-leg swelling, heaviness, aching or visible twisted veins.

An injury, inflammation or infection may cause swelling with pain, warmth, tenderness or colour change. A blood clot in a deep vein can cause swelling and pain, often on one side, and needs prompt assessment. Heart failure and chronic kidney disease can also cause fluid retention, sometimes alongside breathlessness or swelling elsewhere.

Some blood-pressure medicines, anti-inflammatory medicines, hormones and steroids can cause ankle swelling. Do not stop a prescribed medicine without medical advice. Obesity can place extra pressure on the veins and make fluid pooling more likely.

If the swelling is mild and affects both legs, take regular walking breaks, avoid sitting with the legs down for long periods, and raise the legs when resting. Comfortable footwear and avoiding tight socks around the calf may help. Keep the skin clean and check for cracks, blisters or wounds.

Arrange a clinical assessment if swelling persists, keeps returning, or has no clear explanation. A clinician may examine both legs, review medicines and health conditions, and decide whether blood tests or an ultrasound are needed. Avoid massage or compression garments until a clinician has considered a possible clot or poor arterial circulation.

Seek urgent medical help for sudden swelling in one leg, especially with calf pain, warmth, redness or tenderness. Call emergency services if leg swelling occurs with sudden breathlessness, chest pain, coughing blood, fainting or severe weakness, because a clot can travel to the lungs.

Get prompt care for rapidly worsening swelling, fever with a hot painful area, blue or unusually pale skin, severe pain, or swelling after a significant injury. Breathlessness when lying down or a sudden increase in swelling in both legs also needs prompt assessment.

Ask what might explain the location and timing of the swelling, whether one-sided swelling changes the level of concern, and whether your medicines could contribute. You can also ask whether you need testing for a clot, vein disease, heart problems or kidney problems, and which movement, elevation or compression measures are suitable for you.