A clinician may recommend an ultrasound to assess blood flow and check whether the veins are functioning properly.
Heart Failure
The heart pumps blood throughout the body. When it cannot pump effectively, blood may begin to back up in the circulation.
This can increase pressure in the veins and contribute to fluid accumulation in the legs, ankles, and feet.
Some people with heart failure notice swelling in both legs. They may also experience breathlessness, unusual tiredness, difficulty exercising, or a need to sleep with their upper body elevated.
In some cases, fluid may accumulate in the lungs, making breathing difficult.
Leg swelling alone cannot diagnose heart failure. However, swelling accompanied by breathlessness, rapid weight gain, or worsening exercise tolerance deserves medical attention.
Sudden or severe breathing difficulty requires emergency care.
Kidney Disease
The kidneys help regulate the body's salt and water balance. When kidney function declines, the body may retain more sodium and fluid than it should.
That extra fluid can contribute to swelling in the ankles, feet, legs, hands, or around the eyes.
Some people with kidney disease also have protein leaking into their urine. Losing significant amounts of protein can change the balance of fluid between the bloodstream and body tissues, making swelling more likely.
Other possible signs of kidney problems include changes in urination, foamy urine, fatigue, nausea, and difficulty controlling blood pressure.
However, early chronic kidney disease often causes no noticeable symptoms. Blood and urine tests are needed to assess kidney function accurately.
Liver Disease
The liver produces albumin, an important protein that helps keep fluid inside blood vessels.
When severe liver disease reduces albumin production, fluid may move more easily into surrounding tissues. Changes in blood flow through the liver can also increase pressure in certain veins.
Some people with advanced liver disease develop swelling in their legs as well as fluid accumulation in the abdomen, known as ascites.
Other possible signs include yellowing of the skin or eyes, abdominal enlargement, easy bruising, and fatigue.
These symptoms require medical assessment. A swollen ankle by itself does not indicate liver disease.
Medication Side Effects
Some medications can cause the body to retain fluid.
Examples include certain blood pressure medicines, corticosteroids, hormone treatments, some antidepressants, and nonsteroidal anti-inflammatory drugs such as ibuprofen.
A person may notice swelling after starting a new medicine or changing a dose.
The timing can provide a useful clue, but it does not prove that the medication is responsible. A clinician or pharmacist can review the treatment and decide whether an adjustment is appropriate.
People should not stop prescribed medication without medical advice, particularly medicines used to control blood pressure, heart disease, or other long-term conditions.
Pregnancy and Hormonal Changes
Swelling in the feet and ankles is common during pregnancy, especially in later stages.
The growing uterus can affect blood return from the legs, while hormonal and circulatory changes can encourage fluid retention.
Mild swelling that develops gradually may be part of an ordinary pregnancy. However, sudden or severe swelling, particularly when accompanied by a severe headache, visual changes, upper abdominal pain, or high blood pressure, needs urgent assessment because it may be associated with pre-eclampsia.
Pregnant people should contact their maternity team when swelling changes suddenly or is accompanied by other concerning symptoms.
Prolonged Sitting and Standing
A long flight, a lengthy car journey, or a workday spent mostly at a desk can contribute to swelling.
When the legs remain still, the calf muscles do not contract as frequently to help move blood upward. Fluid may gradually collect around the ankles.
Standing for many hours can also increase pressure in the veins of the lower legs.
This type of swelling may improve with gentle movement, walking, and leg elevation. But it should not automatically be dismissed, especially if it is new, severe, one-sided, or accompanied by pain.
6. Deep Vein Thrombosis: The Warning That Should Never Be Overlooked
Among the possible causes of leg swelling, deep vein thrombosis deserves particular attention because it can become life-threatening.
DVT occurs when a blood clot forms in a deep vein, usually in the leg. The clot can partially or completely obstruct blood flow.
The affected leg may become swollen, painful, warm, or discolored. Some people experience tenderness in the calf or thigh, while others notice that one leg looks larger than the other.
The swelling may develop relatively quickly.
Why a Blood Clot Can Be Dangerous
The greatest danger is that part of the clot may break away and travel through the bloodstream to the lungs.
This can cause a pulmonary embolism.
A pulmonary embolism may lead to sudden breathlessness, chest pain, a rapid heartbeat, coughing up blood, dizziness, or fainting. It can be life-threatening and requires emergency medical treatment.
Anyone who has symptoms suggesting DVT should seek urgent medical assessment. If leg swelling or pain is accompanied by chest pain or shortness of breath, emergency services should be contacted immediately.
Who Has a Higher Risk of DVT?
Certain circumstances increase the likelihood of developing a blood clot.
These include:
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A previous history of DVT or pulmonary embolism.
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Cancer, particularly during active treatment.
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Major surgery or recent hospitalization.
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Long periods of immobility.
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Certain inherited blood-clotting conditions.
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Pregnancy and the period after childbirth.
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Some hormone-based medications.
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Older age.
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Certain chronic medical conditions.
Having one or more risk factors does not mean that a clot will definitely develop. It does mean that new symptoms should be taken seriously.
Cancer itself can increase the risk of blood clots, and some cancer treatments may raise that risk further. This is one reason doctors pay close attention to sudden leg swelling in people receiving cancer care.
Why You Should Not Try to Diagnose DVT at Home
A swollen calf can have several explanations. A muscle injury, infection, venous insufficiency, and DVT may produce overlapping symptoms.
A person cannot reliably determine whether a clot is present by pressing the calf, measuring the ankle, or comparing the appearance of both legs.
Medical assessment may involve a physical examination, evaluation of risk factors, blood tests, and an ultrasound scan of the veins.
The correct testing approach depends on the clinical situation.
Do not massage a leg that is suddenly swollen and painful when a blood clot is a possibility. Seek medical assessment rather than attempting home treatment.
7. What Does the Skin Around a Swollen Ankle Tell You?
The photograph in the supplied post shows a rounded, puffy area around the ankle, highlighted with a red circle.