Why Are My Ankles and Feet Swollen? 10 Possible Causes and When to Worry

You take off your shoes at the end of the day and notice that your ankles look puffier than usual.

Perhaps your socks have left deep marks around your legs, your shoes suddenly feel tight, or pressing your finger against the swollen area leaves a temporary dent.

You may start wondering:

Why are my ankles and feet swollen?

Swelling in the feet, ankles or lower legs is often caused by a build-up of fluid in the tissues, known as oedema (edema).

Sometimes the explanation is relatively simple, such as sitting or standing for a long time, eating a particularly salty meal or being pregnant. Certain medications can also cause swelling.

However, persistent or sudden swelling can occasionally be associated with problems involving the veins, heart, kidneys, liver or a blood clot.

The pattern matters.

Swelling in both legs that gradually develops during the day can mean something different from one leg suddenly becoming swollen, painful and warm.

Here are 10 possible reasons your ankles or feet may be swollen.

1. You May Have Been Sitting or Standing for Too Long

Gravity plays an important role in lower-leg swelling.

When you remain upright for many hours, fluid can accumulate in the tissues of your feet and ankles.

This may be more noticeable after:

• working on your feet all day
• sitting at a desk for long periods
• travelling on a long flight
• taking a lengthy car journey
• having very little physical activity

The swelling may become more noticeable towards the evening and improve after you elevate your legs or sleep overnight.

The NHS lists prolonged sitting or standing among common causes of swollen ankles, feet and legs.

2. Eating Too Much Salt May Contribute

Salt contains sodium, which plays an important role in regulating fluid in the body.

Eating a very salty diet can contribute to fluid retention in some people.

High-salt foods can include:

• processed meats
• some ready meals
• salty snacks
• takeaway foods
• instant noodles
• certain sauces and seasonings
• some canned foods

If your swelling appears after an unusually salty meal and disappears relatively quickly, temporary fluid retention may be involved.

However, persistent swelling should not automatically be blamed on salt.

3. Hot Weather Can Make Your Ankles Swell

Some people notice that their shoes become tighter or their ankles puff up during very warm weather.

Heat can cause blood vessels to widen, and fluid may move into surrounding tissues.

This can be particularly noticeable after spending hours standing or sitting in hot conditions.

Mild swelling associated with heat may improve after cooling down, moving around and elevating your legs.

New, severe or persistent swelling still deserves attention regardless of the weather.

4. Pregnancy Can Cause Swollen Feet and Ankles

Mild swelling of the ankles and feet is common during pregnancy.

The body holds more fluid during pregnancy, and the growing uterus can also affect circulation from the legs.

Swelling may become more noticeable:

• later in pregnancy
• towards the end of the day
• during hot weather
• after standing for long periods

However, sudden or rapidly increasing swelling during pregnancy, particularly involving the face or hands or occurring with severe headache, vision problems, pain below the ribs or feeling very unwell, requires prompt medical assessment.

Not all pregnancy-related swelling should simply be considered normal.

5. Certain Medicines Can Cause Swelling

Medication is another important possibility.

The NHS lists several types of medicines that may contribute to oedema, including some:

• blood pressure medicines
• contraceptive pills
• hormone treatments
• antidepressants
• steroids

If your ankle swelling started after beginning a new medication or changing a dose, mention this to your doctor or pharmacist.

Do not stop prescribed medication yourself.

A healthcare professional can determine whether the medicine is likely to be contributing and whether anything should be changed.

6. Varicose Veins or Venous Insufficiency Could Be Involved

Veins in your legs have valves that help blood travel back towards your heart.

If those valves do not work efficiently, blood can pool in the lower legs. This is known as chronic venous insufficiency.

Harvard Health identifies chronic venous insufficiency as a common cause of lower-leg and ankle oedema.

You may notice:

• swelling that becomes worse later in the day
• aching or heavy legs
• visible varicose veins
• skin changes around the ankles
• swelling that improves after elevating your legs

Persistent symptoms should be assessed because treatment depends on the severity and underlying cause.

7. An Injury or Infection Can Cause Swelling

Not all swelling is caused by fluid retention throughout the body.

A local injury can make one ankle or foot swell.

Possible causes include:

• ankle sprain
• muscle strain
• fracture
• insect bite or sting
• skin or soft-tissue infection

In these situations, the affected area may also be:

• painful
• tender
• red
• warm
• difficult to move

Significant swelling after an injury or swelling accompanied by redness, heat or fever deserves medical attention.

8. A Blood Clot Can Cause One-Sided Leg Swelling

One of the more important causes of sudden swelling is deep vein thrombosis (DVT).

A DVT is a blood clot that develops in a deep vein, usually in a leg.

Possible symptoms can include:

• swelling in one leg
• calf or thigh pain
• tenderness
• warmth
• skin colour changes

Not everyone with a DVT has all of these symptoms.

The key point is that sudden unexplained swelling in one leg should not simply be treated at home and ignored.

The NHS recommends urgent assessment for unexplained swelling affecting one ankle, foot or leg.

A clot can become dangerous if part of it travels to the lungs.

9. Heart Problems Can Sometimes Cause Leg Swelling

Certain heart conditions can make it harder for the heart to pump blood effectively.

Fluid can then accumulate in the body, including the ankles and legs.

Depending on the cause, swelling may occur alongside:

• shortness of breath
• reduced exercise tolerance
• unusual tiredness
• difficulty breathing when lying flat
• rapid weight gain from fluid retention

Swollen ankles alone do not mean you have heart disease.

There are many more common explanations.

However, persistent swelling combined with breathing difficulties deserves medical assessment.

10. Kidney or Liver Problems Can Sometimes Cause Swelling

Your kidneys help regulate fluid and salt balance.

If kidney function is significantly impaired, excess fluid can accumulate in the body.

Certain liver conditions can also affect proteins and fluid balance, contributing to swelling.

Depending on the underlying condition, other symptoms may occur.

For example, you might experience:

• unusual tiredness
• changes in urination
• swelling elsewhere
• abdominal swelling
• loss of appetite
• other unexplained symptoms

Heart, kidney and liver problems are recognised potential causes of oedema.

But swollen ankles by themselves cannot tell you which, if any, of these conditions is responsible.

Why Are My Ankles Swollen at the End of the Day?

Swelling that becomes progressively more noticeable as the day continues can occur because gravity encourages fluid to collect in the lower legs.

Long periods of standing or sitting can make this worse.

Venous insufficiency can also produce this pattern.

You may notice that:

morning → little or no swelling

afternoon → ankles begin looking puffy

evening → socks leave deeper marks

after sleeping → swelling improves

Although this pattern can have a relatively straightforward explanation, persistent daily swelling should still be discussed with a healthcare professional.

Why Are Both of My Feet Swollen?

Swelling in both feet may occur with:

• prolonged sitting or standing
• high salt intake
• hot weather
• pregnancy
• certain medications
• venous problems
• some heart, kidney or liver conditions

The cause cannot be determined from swelling alone.

Whether it developed suddenly or gradually and whether you have other symptoms are important clues.

Why Is Only One Foot or Ankle Swollen?

One-sided swelling deserves particular attention.

Possible causes include:

• injury
• infection
• insect bite or sting
• venous problems
• a blood clot

If one leg suddenly becomes swollen without an obvious explanation—particularly if it is painful, warm or discoloured—seek prompt medical advice.

Why Do My Socks Leave Deep Marks Around My Ankles?

A mild temporary sock mark does not necessarily indicate disease.

But deep indentations accompanied by visible swelling may indicate fluid accumulation.

Some swelling is described as pitting oedema.

If pressing a finger firmly into the swollen skin leaves a dent that remains briefly after you remove your finger, that can be a sign of pitting oedema.

It does not identify the underlying cause by itself.

Can Being Overweight Cause Swollen Ankles?

Excess body weight can contribute to lower-leg swelling in some people by increasing pressure on the veins and making circulation from the legs more difficult.

The NHS includes being overweight among common factors associated with oedema.

However, new swelling should not automatically be attributed to weight, particularly if it is sudden, severe or affects only one side.

Can Dehydration Cause Swollen Ankles?

It may sound logical to assume every fluid problem comes from dehydration, but persistent ankle swelling has many possible causes.

Do not deliberately reduce your water intake simply because your ankles are swollen.

In some situations, inappropriate fluid restriction could make matters worse.

The appropriate amount of fluid depends on your overall health and the reason for the swelling.

What Can Help Mild Swollen Ankles and Feet?

If there is no concerning underlying cause, several simple measures may help.

Elevate your legs

When resting, raise your legs on a chair or pillows.

Keep moving

Gentle walking and regular movement can help circulation.

Avoid remaining in one position for hours

If possible, alternate sitting, standing and walking.

Wear comfortable footwear

Tight shoes can become uncomfortable when your feet swell.

Consider your salt intake

If your diet is very high in salt, reducing excessive salt intake may be appropriate.

The NHS recommends elevation, gentle exercise and avoiding long periods of sitting or standing as measures that may ease uncomplicated swelling.

Do not begin taking “water tablets” or diuretics on your own to treat unexplained swelling.

When Should You See a Doctor About Swollen Ankles?

Arrange a medical assessment if swelling:

• persists for several days without an obvious explanation
• keeps returning
• becomes progressively worse
• significantly affects both legs
• occurs alongside other unexplained symptoms
• develops after starting a new medication
• occurs when you already have a heart, kidney or vein condition

Seek urgent medical assessment for unexplained one-sided swelling, severe or sudden swelling, significant pain, redness or heat, or swelling accompanied by fever.

Seek emergency medical help if leg swelling occurs with:

• sudden or severe shortness of breath
• difficulty breathing
• chest pain or tightness
• coughing up blood
• fainting or severe lightheadedness

These symptoms can occur when a blood clot travels to the lungs and require immediate treatment.

Frequently Asked Questions

Is it normal for ankles to swell after standing all day?

Mild swelling can occur after prolonged standing because gravity encourages fluid to collect in the lower legs.

Persistent, worsening or significant swelling should still be assessed.

Can eating too much salt make your feet swell?

Yes. A high salt intake can contribute to fluid retention in susceptible people.

Should I drink more water if my feet are swollen?

There is no universal answer because swelling has many possible causes.

Maintain normal hydration unless a healthcare professional has given you specific fluid instructions.

Why does my ankle swelling disappear overnight?

Lying down reduces the effect of gravity on fluid accumulation in the lower legs, so some forms of swelling improve overnight.

Can blood pressure medicine cause swollen ankles?

Yes. Some blood pressure medicines can contribute to ankle swelling.

Do not stop prescribed blood pressure medication without discussing it with your healthcare professional.

Is one swollen ankle more worrying than two?

Sudden unexplained swelling affecting only one leg can sometimes indicate a blood clot or another local problem and warrants prompt assessment.

Does swollen feet mean kidney problems?

Kidney problems can cause swelling, but there are many other possible causes.

Swollen feet alone cannot diagnose kidney disease.

The Bottom Line

If you're wondering “Why are my ankles and feet swollen?”, first look at the pattern.

Long periods of sitting or standing, salty foods, hot weather, pregnancy and certain medications are common possibilities.

Varicose veins and problems with blood returning through the leg veins can also contribute.

Less commonly, persistent swelling can be associated with heart, kidney or liver problems, while sudden unexplained swelling in one leg can be a warning sign of a blood clot.

The biggest distinction is this:

Gradual, mild swelling in both ankles after a long day is very different from one leg suddenly becoming swollen, painful and warm.

If swelling is persistent, worsening, unexplained or accompanied by concerning symptoms, get it medically assessed.

Related Reading

• Why Do I Feel Dizzy When I Stand Up? 8 Possible Causes and When to Worry
• Why Am I Always Thirsty? 8 Possible Reasons You Feel Thirsty All the Time
• Why Am I Always Cold? 9 Possible Reasons You Feel Cold All the Time

Sources and Further Reading

• NHS — Swollen ankles, feet and legs (oedema)
  
  
• Harvard Health — Why are my ankles swollen?
  
  

Medical Disclaimer

This article is for general educational and informational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. If you experience persistent, sudden or unexplained swelling of your ankles, feet or legs, consult an appropriately qualified healthcare professional.