Causes of foot and leg swelling

Swelling is fluid collecting in the tissues. It may affect one side or both, appear suddenly or build gradually, and leave an indentation after pressure. One-sided swelling with pain can have a different cause from swelling in both legs. Varicose veins can impair the return of blood from the legs. Obesity may increase pressure on veins, while heart failure or chronic kidney disease can cause more widespread fluid retention.

Note when the swelling started, whether one or both legs are affected, and any pain, redness, breathlessness or recent travel. Remove tight socks and footwear. Gentle movement and raising the legs while resting may help if prolonged sitting or standing is the trigger. Do not start water tablets, restrict fluids, or use compression garments without clinical advice, particularly if the swelling is new or painful. Review medicines with a clinician or pharmacist.

Get urgent medical help for sudden swelling in one leg, especially with warmth, redness or calf pain, or for swelling accompanied by chest pain, severe breathlessness, faintness or coughing blood. Arrange an appointment for persistent, worsening or recurrent swelling, skin changes, reduced urine, or breathlessness when lying down. These features need assessment rather than home treatment alone.

Ask whether you need an examination, blood or urine tests, or an ultrasound. Mention new medicines, pregnancy, recent injury, long travel, and any history of heart, kidney or vein problems.