What should you know about knee and leg swelling?

Swelling is often fluid collecting in the tissues around the knee, calf, ankle, or foot. It can occur after a sprain, a knock, strenuous activity, or inflammation inside the knee. Sitting or standing for a long time may also make fluid gather in the lower legs.

Swelling in both legs can be linked with problems returning blood through the veins, including varicose veins, or with conditions that affect how the heart or kidneys handle fluid. Body weight can add strain to the knees and legs. Swelling on one side, especially when it starts quickly, needs more prompt assessment because a blood-flow problem is one possible cause.

Look for clues such as pain, warmth, redness, stiffness, bruising, breathlessness, or swelling that leaves a dent after you press the skin. These details help a clinician decide whether the problem is local to the joint or part of a wider fluid imbalance.

If the swelling followed a minor injury, rest the leg, raise it when sitting, and use a wrapped cold pack for short periods. Avoid placing ice directly on the skin. Gentle movement can help prevent stiffness, but stop if pain or swelling increases.

Do not massage a suddenly swollen, painful, warm, or red leg until a clinician has assessed it. Keep a note of when the swelling began, whether it changes during the day, and any new medicines or recent travel. Arrange a medical review if it persists, returns, affects walking, or has no clear explanation.

Seek emergency help if leg swelling occurs with chest pain, sudden breathlessness, fainting, or coughing blood. Get urgent medical assessment for a leg that becomes suddenly swollen, painful, warm, or red, particularly on one side.

Contact a clinician promptly if you have fever with a hot, swollen joint, cannot bear weight, or the swelling followed a significant injury. A routine appointment is suitable for ongoing swelling, repeated episodes, skin changes, or swelling in both legs that is gradually worsening.

Ask what may be causing the swelling and whether you need an examination, blood tests, or an ultrasound. Tell the clinician about pain, injury, long periods of sitting, recent travel, breathlessness, kidney or heart symptoms, and every medicine you take. Ask which activities are suitable while the cause is being checked and what change should prompt urgent help.