Swollen ankles and fluid retention: what it can mean

Swollen ankles are often caused by fluid building up in the tissues of the lower legs and feet. This is known as oedema and can happen after sitting or standing for long periods, particularly if movement is limited. But persistent, sudden or unexplained swelling can sometimes have another cause.

For people who use a wheelchair or spend much of the day sitting, swollen ankles and lower legs are particularly common. Reduced muscle activity, keeping the legs in a lowered position and the effect of gravity can all make it harder for blood and fluid to move back towards the heart.

In many cases, ankle swelling is related to position and reduced movement and improves after resting with the legs elevated. However, fluid retention can also be linked to medicines or conditions affecting the heart, kidneys, liver or veins. A blood clot, such as deep vein thrombosis (DVT), can also cause swelling, usually affecting one leg.

What causes swollen ankles and fluid retention?

When you sit for long periods, especially with your legs down, fluid can naturally collect in your lower legs and feet. Moving your legs helps your body shift this fluid back into circulation, so reduced movement can make swelling more noticeable.

This is why swollen ankles can be worse towards the end of the day and improve after lying down overnight or elevating the legs.

Common causes of swollen ankles

Fluid retention can have a number of causes. These include:

• sitting or standing for long periods
• reduced movement or mobility
• eating a diet high in salt
• being pregnant
• certain medicines
• problems with the veins, such as chronic venous insufficiency
• lymphoedema
• conditions affecting the heart, kidneys or liver

Sometimes there is no serious underlying cause, particularly when swelling is mild, affects both ankles and improves with movement or elevation. Persistent or unexplained swelling should still be discussed with a healthcare professional.

When should you worry about swollen ankles?

The way the swelling develops and whether you have other symptoms can provide useful clues.

Swelling is generally less concerning when it affects both ankles or legs fairly evenly, develops gradually and improves after lying down or raising your legs.

However, sudden swelling, swelling affecting one leg, or swelling accompanied by other new symptoms needs more attention.

One swollen ankle or leg

Swelling that develops suddenly and mainly affects one leg can be a sign of deep vein thrombosis (DVT), particularly if the affected area is painful, warm, red or has changed colour.

DVT is a blood clot that forms in a deep vein, usually in the leg. It requires urgent medical assessment. If you think you may have a DVT, contact your GP urgently or call NHS 111 for advice.

If swelling is accompanied by sudden breathlessness or chest pain, call 999. These can be signs that a blood clot has travelled to the lungs, causing a pulmonary embolism.

Swollen ankles and breathlessness

Swollen ankles can sometimes occur alongside heart failure, particularly when there is also breathlessness, tiredness or difficulty breathing when lying down.

However, ankle swelling has many possible causes and does not necessarily mean there is a problem with the heart. If swelling is persistent or occurs alongside new breathlessness, speak to a GP.

What can help reduce fluid retention?

If your swollen ankles are linked to prolonged sitting, standing or reduced movement, some simple measures may help.

• Raise your legs. Elevating your legs can help counteract gravity and encourage fluid to move away from the lower legs. Try raising your legs for periods during the day where this is comfortable and appropriate for you.
• Keep moving. Moving your legs, feet and ankles can support circulation. If you use a wheelchair or have limited lower-limb movement, even small movements or passive exercises may be helpful. A physiotherapist can advise on suitable exercises for your circumstances.
• Stay hydrated. Drinking enough fluid is important for general health. Restricting your fluid intake without medical advice is not a good way to manage swollen ankles.
• Watch your salt intake. Eating too much salt can contribute to fluid retention. Reducing foods that are high in salt may help support a healthy fluid balance.
• Ask about compression. Compression stockings or other compression garments can help some people with swelling, but they are not suitable for everyone. If you have problems with your circulation, speak to a healthcare professional before using them.

What is pitting oedema?

If you press a finger gently into swollen skin and a dent remains for a short time, this is known as pitting oedema. It is a sign that excess fluid has collected in the tissues.

Swelling that does not leave a dent is known as non-pitting oedema. The type of swelling can provide healthcare professionals with useful information, but it can't identify the cause on its own. For example, lymphoedema can cause different types of swelling depending on how long it has been present.

If you have persistent swelling and are unsure what is causing it, speak to a GP.

Looking after swollen legs and ankles

Long-term swelling can make the skin on the lower legs more vulnerable. Swollen skin can become stretched and fragile, while reduced mobility can increase the risk of pressure damage.

Check your feet, ankles and legs regularly for changes such as redness, broken skin, blisters, sores or areas that feel unusually warm or painful. Keep the skin clean and dry and make sure pressure is relieved regularly if you spend long periods sitting.

If you develop a wound or sore that does not appear to be healing, seek medical advice.

When should you see a doctor about swollen ankles?

Speak to a GP if swelling is new, persistent, getting worse or you cannot explain why it is happening. You should also seek advice if swelling does not improve with measures such as movement or elevation.

Seek urgent medical advice if one leg or ankle becomes swollen suddenly, particularly if there is pain, warmth, redness or a change in skin colour.

Call 999 if you have swelling alongside sudden breathlessness or chest pain, as these can be signs of a pulmonary embolism.

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This article is for general health information purposes and does not constitute medical advice. If you experience sudden asymmetrical leg swelling, pain or warmth in one leg, or new breathlessness, seek medical attention promptly.