Swelling of the arms, feet, ankles, and legs is called edema. It's caused by extra fluid collecting in the tissues. Because of gravity, extra fluid in the body settles to the lowest part. That's why the legs and feet are most affected. You have swelling in a single leg.
Some of the causes for swelling in only one leg include:
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Infection in the foot or leg.
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Muscle strain or tear in the affected leg.
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Blockage of the leg's lymphatic system.
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A Baker's cyst (located behind the knee).
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Long-term problem with a vein not working well (venous insufficiency).
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Swollen, twisted vein in the leg (varicose veins).
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Insect bite or sting on the foot or leg.
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Injury or recent surgery on the foot or leg.
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Blood clot in a deep vein of the leg (deep vein thrombosis or DVT).
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Inflammation of the joints of the lower leg.
Medical treatment will depend on what is causing your swelling.
Home care
Follow these guidelines when caring for yourself at home:
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Don’t wear tight clothing.
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Keep your legs up while lying down or sitting.
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Take any medicines as directed.
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If infection, injury, or recent surgery is the cause of your swelling, stay off your legs as much as possible until your symptoms get better.
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If you have venous insufficiency or varicose veins, don’t sit or stand in one place for a long time. Take breaks and walk around every few hours. Talk with your health care provider about wearing support stockings to help reduce swelling during the day.
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Wear compression stockings with your provider's approval.
Follow-up care
Follow up with your health care provider as advised.
Call 911
Call
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Shortness of breath or trouble breathing
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Chest pain or discomfort
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Coughing up blood
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Fainting or loss of consciousness
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Fast heartbeat, lightheadedness, or dizziness
When to get medical advice
Contact your health care provider right away if any of these occur:
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Increased pain, swelling, warmth, or redness of the leg, ankle, or foot
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Fever of 100.4°F (38ºC) or higher, or as advised by your provider
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Weakness
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Shaking chills
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Drenching sweats
Online Medical Reviewer: Robyn Zercher FNP
Online Medical Reviewer: Stacey Wojcik MBA BSN RN
Online Medical Reviewer: Steven Kang MD
Date Last Reviewed: 03/01/2025
© 2000-2026 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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