Reasons for swelling in the leg

Swelling in both legs often reflects fluid collecting in the tissues or reduced return of blood through the veins. Long periods of sitting or standing, warm weather, excess body weight, and some medicines can contribute. Varicose veins may cause aching, heaviness, skin changes, and swelling that is worse later in the day.

Swelling in one leg may follow an injury, infection, or a problem with a vein and deserves closer attention, especially when it appears suddenly. Heart failure and chronic kidney disease can also present with swelling, sometimes alongside breathlessness, tiredness, or changes in urination. Swollen ankles are a related symptom to discuss with a clinician.

Note when the swelling began, whether one or both legs are affected, and whether it changes overnight or after walking. Remove tight socks, take gentle movement breaks during travel or desk work, and raise the legs when resting if this is comfortable. Avoid changing prescribed medicines or starting compression garments without medical advice, particularly if the swelling is new or painful.

Get urgent medical help for sudden one-sided swelling with pain, warmth, or redness; swelling with chest pain, faintness, or difficulty breathing; or a leg that becomes pale, blue, cold, or numb. Arrange a prompt assessment when swelling persists, keeps returning, is associated with fever or a wound, or comes with breathlessness or a marked change in urination.

Ask whether the pattern suggests a vein, medicine, heart, kidney, or local cause; whether you need an examination or tests; and which movement, elevation, or compression measures are suitable for you.