Key takeaways
- Mild swelling in both ankles after a long flight or on a hot day is common and usually settles on its own.
- It happens because fluid pools in the lower legs when you sit still or when blood vessels widen in the heat.
- Moving your legs, raising your feet and staying hydrated help most people.
- Swelling in one leg, especially with pain, needs urgent medical advice.
Why ankles swell
Your calf muscles help push blood back up from your legs to your heart. When you sit still for hours, or when it's hot, that system works less efficiently.
Fluid then collects in the tissues of your feet and ankles. The medical name is oedema, and the NHS oedema page covers the common causes.
On a long flight
| What to do | Why it helps |
|---|---|
| Walk the aisle every hour or two | Gets your calf muscles pumping |
| Do seat exercises | Circle your ankles and lift your heels and toes regularly |
| Drink water | Cabin air is dry; stay hydrated |
| Wear loose clothing | Tight waistbands and socks restrict circulation |
| Ask about flight socks | A pharmacist can advise on compression stockings and fit |
| Keep bags out of your footwell | Gives you room to move your legs |
In hot weather
In the heat, your blood vessels widen to help you cool down, which makes it easier for fluid to leak into the tissues.
- Raise your feet above hip level when you rest
- Keep moving: short walks are better than long periods of standing
- Drink regularly and go easy on salty snacks
- Cool your feet with a cool (not ice-cold) footbath
- Choose comfortable shoes with room to swell
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Warning signs that need urgent advice
- Swelling in one leg, with pain, warmth, tenderness or redness, especially after a flight: this can be a sign of a blood clot (DVT). Call 111 or get urgent medical help.
- Swelling with shortness of breath or chest pain: call 999.
- Sudden swelling of the face, hands or feet in pregnancy: contact your midwife or maternity unit.
- Swelling that doesn't go down overnight, or keeps coming back: see your GP.
Questions people ask
How long do swollen ankles last after flying?
Mild swelling usually goes down within a day or two of moving around normally.
Do flight socks work?
Compression stockings can help some people. Ask a pharmacist about the right type and fit, especially if you've had clots before.
Should I drink less to stop swelling?
No. Staying hydrated helps your body balance fluid.
Why do my ankles swell in summer?
Heat widens your blood vessels, so fluid collects more easily in your lower legs.
Is swelling in both ankles serious?
Mild swelling after travel or heat usually isn't. Swelling that's persistent, painful or comes with breathlessness needs checking.
Sources: NHS: oedema · NHS: DVT · GB NHC register
This article is general information, not medical advice. Food supplements should not replace a varied, balanced diet and healthy lifestyle. If you're worried about swelling, speak to your GP or NHS 111.
