One lower leg swelling: what to know

A deep-vein clot is one cause of swelling in one lower leg, particularly when the area feels painful, warm, tight or tender. A sprain, muscle injury, joint problem, skin infection or impaired lymph drainage can produce similar changes. [Varicose Veins](/conditions/varicose-veins/) can cause aching and swelling after standing. [Heart Failure](/conditions/heart-failure/) and [Chronic Kidney Disease](/conditions/chronic-kidney-disease/) can cause swelling through fluid balance changes, but this is often present in both legs.

The appearance is not enough to identify the cause. A clinician may ask about recent travel, surgery, pregnancy, injury, medicines and activity, then examine the skin, pulses and veins. Testing may include an ultrasound.

Seek same-day medical advice for a new or unexplained swollen lower leg. Record when it began, whether it is getting larger, and whether the foot, ankle, calf or knee is involved. Mention pain, redness, warmth, fever and any recent operation or long period of sitting. Avoid deep massage and strenuous exercise until you have advice. Keep the leg supported comfortably; do not start compression treatment unless a clinician recommends it. See [Swollen Ankles](/symptoms/swollen-ankles/) for related symptom information.

Call emergency services for sudden breathlessness, chest pain, coughing blood, fainting or collapse. Get urgent assessment today for severe or rapidly increasing swelling, a hot painful calf, spreading redness, fever, a pale or blue foot, new numbness or severe pain. These signs can indicate a clot, infection or a circulation problem that needs rapid treatment.

Ask whether your examination suggests a vein, infection, injury or fluid-related cause; whether an ultrasound is appropriate; what activity is safe; and how to recognise a change that needs emergency help. Ask how soon the swelling should improve and who to contact if it does not.