Swelling in the legs can occur for many reasons, including standing or sitting for long periods, excessive salt intake, varicose veins, or medical conditions affecting the heart, kidneys, liver, or thyroid. The first step is to notice whether the swelling affects one leg or both legs, and whether it is associated with pain, redness, or shortness of breath. To help reduce swelling, try keeping your legs raised while resting, avoid standing or sitting for long periods, reduce salt intake, and engage in regular light exercise such as walking. Do not take water pills (diuretics) or other medicines without consulting a doctor. You should see a doctor if the swelling persists, worsens, or keeps returning. Seek urgent medical attention if you develop sudden swelling in one leg, severe pain, chest pain, or difficulty breathing, as these symptoms may indicate a serious condition that requires immediate treatment.