Common Causes of Swelling in the Feet and Ankles

What causes swollen feet? Common reasons include sitting or standing for long periods, hot weather, injuries, pregnancy and certain medicines. Swelling may result from a local problem, such as an injury or infection, or from a condition affecting the body's fluid balance or circulation. Some cases are temporary, while others may relate to conditions affecting the heart, kidneys, liver, or veins. The location, speed of onset and accompanying symptoms help determine how urgently medical attention is needed{{ref:kzosfoh9}^[2].

Swelling occurs when excess fluid collects in body tissues. The medical term for this is oedema. It often affects the feet and ankles because fluid tends to accumulate in the lower parts of the body^[1].

This article explains common causes of swollen feet, warning signs and factors that may contribute to the problem. It provides general health information and cannot establish the cause of swelling in an individual.

When are swollen feet a medical emergency?

Mild swelling after prolonged sitting or standing may improve with movement and rest. However, certain symptoms need immediate attention because they can indicate a serious underlying problem.

Seek emergency medical help if foot or leg swelling occurs alongside^[1][2]:

• Sudden or severe difficulty breathing
• Chest pain, tightness or pressure
• Coughing up blood
• Fainting, collapse or severe light-headedness
• A rapid or noticeably irregular heartbeat, particularly with breathlessness or chest discomfort

These symptoms can indicate a pulmonary embolism, in which a blood clot blocks a blood vessel in the lungs. Other serious conditions can also cause these symptoms^[3].

Some situations require urgent medical assessment even without breathing problems.

These include:

• Sudden, severe or unexplained swelling.
• A swollen foot or leg that is red, hot or painful.
• Swelling accompanied by fever or chills.
• New swelling in someone with diabetes.
• Worsening swelling in someone with known heart, kidney or liver disease.

If a person with diabetes develops a warm, red or swollen foot, seek urgent medical assessment, even if there is no obvious injury or significant pain. This may indicate Charcot neuroarthropathy, which can rapidly damage the bones and joints of the foot. Avoid putting weight on the affected foot until it has been assessed. Prompt treatment is essential to prevent permanent deformity and reduce the risk of limb-threatening complications.^[3]

Do not wait for swelling to become painful before seeking advice. Some potentially serious causes may initially produce few other symptoms.

Could this be a blood clot (DVT)? Key warning signs

A deep vein thrombosis (DVT) is a blood clot that forms in a deep vein, usually in the leg. It can obstruct blood flow and cause swelling. If part of the clot travels to the lungs, it can cause a life-threatening pulmonary embolism^[4][5].

DVT commonly affects one leg rather than both. Possible warning signs include:

• Swelling in one leg, including the calf or thigh
• Pain or tenderness, often in the calf
• Skin that feels warmer than the surrounding area
• Redness or a darker skin colour around the affected area

The symptoms can vary, and some people with DVT have no obvious symptoms. Therefore, the absence of pain does not reliably rule out a clot^[4][5].

When to seek help: New, unexplained swelling in one leg, with or without pain, warmth or redness, needs urgent medical assessment. If breathlessness or chest pain develops, seek emergency help immediately^[4][5].

One-sided vs both-feet swelling: What the pattern can tell you

Whether one foot or both feet are swollen can provide useful clues. However, the pattern alone cannot confirm the cause.

These patterns overlap, and the same condition can cause different symptoms in different people^[1][2].

Pay attention to when the swelling began, whether it affects one or both feet, and whether it comes with pain, redness, warmth, breathlessness or changes in urination. This information can help a healthcare professional assess possible causes.

Common, non-urgent causes of swollen feet

Several everyday circumstances can lead to swelling without necessarily indicating a serious illness. However, persistent, unexplained or worsening swelling should not automatically be attributed to these factors^[1][2].

1. Sitting or standing for long periods

Remaining in one position for a long time can allow fluid to collect in the lower legs and feet. This may happen during long journeys, desk work or jobs that involve standing for hours.

2. Hot weather

Hot weather can contribute to swelling in the lower limbs, particularly after prolonged standing or walking. This happens partly because changes in blood vessels can encourage fluid to move into surrounding tissues^[1][2].

3. High salt intake

A high-salt diet can contribute to fluid retention, particularly in people with certain heart, kidney or other medical conditions. Packaged snacks, pickles, papad and some processed foods can contribute to high salt intake when eaten frequently.

4. Pregnancy

Gradual swelling in the feet and ankles is common during pregnancy. However, sudden or rapidly worsening swelling, especially in the face or hands, needs immediate assessment by your maternity care team. Seek immediate advice if swelling occurs with a severe headache, vision changes, pain below the ribs or feeling very unwell, as these can be warning signs of pre-eclampsia, a pregnancy-related condition involving high blood pressure^[6].

5. Injury or local inflammation

A sprain, strain, insect bite or infection can cause swelling around the affected area. Pain, warmth, redness or difficulty bearing weight may also occur, depending on the cause.

6. Vein problems

Veins carry blood from the legs back towards the heart. When the valves in these veins do not work effectively, blood can pool in the lower limbs. This may lead to swelling, heaviness, skin changes or visible varicose veins^[1][2].

Does diabetes cause swollen feet?

Yes, diabetes can be associated with swollen feet, although swelling is not an inevitable symptom of this disease. The cause may involve complications affecting the kidneys, circulation or heart, or a side effect of certain medicines^[7][8].

Diabetes can affect the kidneys over time. When kidney function declines, the body may retain excess fluid and salt, leading to swelling in the feet, ankles or other areas^[7].

Diabetes can also damage nerves and affect blood flow to the feet. Reduced sensation may make it harder to notice injuries, blisters or infections. Swelling accompanied by redness, warmth, wounds or skin changes therefore deserves particular attention. In people with diabetes, a warm, red or swollen foot can sometimes indicate Charcot neuroarthropathy, a condition that affects the bones and joints of the foot. It may develop even without a noticeable injury or severe pain. Prompt medical assessment is important to reduce the risk of long-term foot damage^[3][8].

Some medicines used for diabetes can also contribute to fluid retention. For example, pioglitazone can cause or worsen swelling and may increase the risk of heart failure in susceptible people^[9].

If you have diabetes and notice new swelling in your feet, ankles or legs, seek medical advice promptly. Do not assume that it is simply a result of diabetes or change prescribed medicines without professional guidance^[1][9].

Other medical causes of swollen feet

When swelling continues, returns frequently or occurs without an obvious explanation, an underlying health condition may be involved.

The following conditions are among the possible causes:

• Heart conditions: When the heart cannot pump blood effectively, fluid may accumulate in the legs and other tissues. Breathlessness or a noticeable reduction in exercise tolerance may occur as well^[1][2].
• Kidney disease: The kidneys help regulate fluid and salt balance. Reduced kidney function can lead to fluid retention and swelling^[7].
• Liver disease: Some advanced liver conditions can reduce albumin production, a protein that helps keep fluid within blood vessels. This can contribute to swelling in the legs or abdomen^[1][2].
• Thyroid disorders: Certain thyroid conditions, such as hypothyroidism, can cause tissue swelling^[1].
• Lymphatic problems: Damage or blockage in the lymphatic system can prevent fluid from draining properly from tissues, causing persistent swelling.
• Infections: Skin and soft tissue infections can produce swelling, often with warmth, redness, tenderness or fever^[1][2].

These conditions cannot be distinguished reliably from one another by looking at the swelling alone. A healthcare professional may review medical history and medicines, examine the affected area and arrange tests when needed.

Can medicines cause swollen feet?

Yes. Some medicines can cause fluid retention or affect circulation. Examples include certain blood pressure medicines (calcium-channel blockers such as amlodipine and nifedipine), corticosteroids (prednisolone and methylprednisolone), hormone treatments (oestrogen and progesterone) and some antidepressants (such as amitriptyline and mirtazapine)^[1][2].

If swelling begins after starting a medicine or changing its dose, tell the prescribing clinician when it started. Do not stop or alter a prescribed medicine on your own, as this could affect the condition it treats.

How to relieve non-urgent swelling at home

When swelling is mild, and there are no warning signs, a few everyday measures may help reduce discomfort. These measures are not a substitute for medical assessment when swelling is new, persistent or unexplained^[1][2].

Consider the following general measures:

• Change position regularly: Avoid sitting or standing in one position for extended periods. Gentle movement can help support circulation.
• Raise your legs when resting: Supporting the legs on pillows may help fluid move away from the feet.
• Choose comfortable footwear: Shoes with enough room can reduce pressure on swollen feet.
• Be mindful of salt intake: Frequent high-salt foods can contribute to fluid retention.
• Protect your feet: Keep the skin clean and dry, and check for cuts, blisters or changes in colour, particularly if you have diabetes.

Compression socks may help some people with swelling caused by venous problems, but they are not suitable for everyone. Ask a healthcare professional whether compression is appropriate before using it for new or unexplained swelling, particularly if you have diabetes, reduced foot sensation, poor circulation or a suspected blood clot^[2].

Seek medical advice if the swelling does not improve, keeps returning or becomes worse. Home measures should not delay assessment of possible warning signs.

Conclusion

Swollen feet and ankles can result from prolonged sitting, medication effects, injury, pregnancy or an underlying medical condition. Sudden or unexplained swelling, redness, warmth or pain needs prompt assessment, while breathlessness or chest pain alongside leg swelling requires emergency care. People with diabetes should seek prompt assessment for a new warm, red or swollen foot. The right treatment depends on identifying the cause.

Medical disclaimer: This article is for general educational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Seek urgent medical care for severe or sudden symptoms, and consult a qualified healthcare professional about persistent or unexplained swelling.