Do compression socks help swollen legs and long flights?

Compression socks cut symptomless leg clots on long flights and reduce swelling on planes and at work; the clots that cause symptoms were never measured.

Published October 2026

Short answer

Compression socks reduce leg swelling on long flights and after long days on your feet, and they cut symptomless leg clots on flights. Whether they prevent symptomatic clots or lung clots is unknown. Evidence grade B (Moderate). Meta-analysis of 12 randomised flight trials (2,918 passengers) plus small workplace trials; downgraded once because no symptomatic DVT, pulmonary embolism or death occurred in the flight trials, so those outcomes are unmeasured.

Key takeaways

In 12 randomised trials of 2,918 passengers on flights over five hours, symptomless leg clots were much rarer with compression socks (3 versus 47) [1].
Stockings reduced flight swelling: ankle and calf measured about 5 mm smaller than the uncovered leg on a three-hour flight [2], and the pooled review found less oedema [1].
In workplace trials, lower-leg volume fell by about 19 mL in hairdressers and vein symptom scores improved in hospital staff who stood for hours [3][4].
No flight trial recorded a symptomatic DVT, pulmonary embolism or death, so the outcomes that worry travellers most are unmeasured [1].
Severe leg-artery disease and poorly controlled heart failure are contraindications, and people with diabetes and nerve damage should get advice first [5][6].

The short version

Wearing compression socks on a long flight cuts the number of symptomless blood clots that form in the legs, and it reduces ankle and calf swelling [1]. The same socks also reduce leg swelling and heaviness after long days of standing or sitting [4][3]. The big unknown: no flight trial recorded a symptomatic clot, a lung clot or a death, so it is unknown whether the socks prevent the clots that send people to hospital [1].

What the studies show

The strongest evidence comes from a 2021 Cochrane review that pooled 12 randomised trials with 2,918 passengers on flights longer than five hours [1]. In the trials that tested stockings on both legs, 50 of 2,637 passengers with follow-up data developed a symptomless deep vein thrombosis: 3 were wearing stockings and 47 were not, meaning the odds of one of these silent clots were about a tenth as high with stockings (odds ratio 0.10, 95% confidence interval 0.04 to 0.25). The review rated that evidence high-certainty. Superficial vein thrombosis was also less common with stockings (4 versus 12; odds ratio 0.45), but that result was not statistically significant. No one had a symptomatic deep vein thrombosis or a pulmonary embolism, and no one died. Stockings also reduced leg swelling, but that evidence was rated low-certainty because trials measured swelling in different ways, and the review reported no significant adverse effects [1].

Two flight trials measured swelling directly. In 34 adults on a three-hour flight, a stocking worn on one leg kept that ankle and calf from swelling while the other leg grew: the difference between legs was about 5 mm after landing [2]. In 47 pilots and passengers on flights of five hours or more, low-pressure compression tights reduced ankle swelling by about 0.19 cm, and travellers rated less leg pain, discomfort and swelling, plus better sleep and alertness [7].

For legs that swell after long spells of standing or sitting, four small randomised trials point the same way. Hairdressers who wore 15-20 mmHg stockings had roughly 19 mL less lower-leg volume on average and about 12% better scores for pain and feelings of swelling [3]. Healthcare workers on six-hour standing shifts had less leg volume with stockings and more without them over 12 months, alongside better vein symptom scores [4]. In a crossover trial of three stockings — two medical (18-20 mmHg) and one light-support (8-10 mmHg) — all reduced lower-leg volume and leg complaints during ordinary days, with the firmer stockings doing more [8]. And during a two-hour standing test, both class I (18-21 mmHg) and class II (23-32 mmHg) stockings reduced lower-leg swelling in healthy people and in people with chronic venous insufficiency [9].

Air travel itself is linked to a modestly higher risk of venous thromboembolism — about 26% higher for every two hours after the first four — and guidelines generally advise compression stockings, rather than drugs, for travellers who have risk factors, and no clot prevention for those who do not [10].

The nuances

The flight trials mostly studied people at low or medium risk of clots — eight trials with 1,598 people at low-to-medium risk and two trials with 1,273 people at high risk — and every flight lasted more than five hours [1]. Swelling relief appeared even on a three-hour hop, though that trial found no change in pain or discomfort [2], while the longer-flight trial did find less discomfort [7]. The workplace trials were small — 44 people in the standing test and 108 hairdressers — and the volunteers were mostly healthy [9][3]. In the flight trials there were no significant adverse effects [1]. Compression is not safe for everyone: severe peripheral arterial disease, where the leg arteries are narrowed, and decompensated (poorly controlled) heart failure are strict contraindications [5], and an expert survey treated advanced arterial disease as an absolute contraindication [11]. People with diabetes and nerve damage need particular care: a case report described second- and third-degree burns in a man with diabetic neuropathy who wore a copper-containing compression sock in the sun [6]. Pregnancy evidence is thin — a review of seven small trials (326 women) found too little data to judge stockings for leg swelling in pregnancy [12]. Full safety details are on the Compression Socks page.

What this means for you

The trials best match healthy passengers on flights of more than four hours and people whose legs swell after long days of standing or sitting [1][4]. For them, the evidence shows a little less swelling and far fewer silent clots, with the important caveat that the clots people notice were never measured [1]. Anyone with narrowed leg arteries, poorly controlled heart failure or diabetes with nerve damage — or who is pregnant — should speak to a doctor before wearing medical compression socks [5][6][12].

Go deeper

Compression Socks — Compression stockings reduce leg swelling on long flights and after long spells of standing or sitting, and they cut symptomless leg clots on flights of more t…

References

Compression stockings for preventing deep vein thrombosis in airline passengers.. Cochrane Database Syst Rev, 2021.
The effect of compression stocking on leg edema and discomfort during a 3-hour flight: A randomized controlled trial.. Eur J Intern Med, 2019.
Compression hosiery for occupational leg symptoms and leg volume: a randomized crossover trial in a cohort of hairdressers.. Phlebology, 2013.
Randomized controlled trial on occupational graduated compression clinical and cost-effectiveness.. Int Angiol, 2023.
[Translated article] Compression Therapy in Dermatology.. Actas Dermosifiliogr, 2024.
Third-degree burn on the neuropathic lower extremity in a patient with diabetes while wearing a copper-containing compression sock: a case report.. Wound Manag Prev, 2021.
A randomised crossover study of low-ankle-pressure graduated-compression tights in reducing flight-induced ankle oedema.. Med J Aust, 2008.
Improvement of occupational leg edema and discomforts (RCT).. Clin Hemorheol Microcirc, 2022.
Influence of compression stockings with different compression classes on lower leg edema and perceived discomfort during a two-hour static standing exposure - a pilot study.. Appl Ergon, 2025.
Travel-Associated Venous Thromboembolism.. Wilderness Environ Med, 2022.
Indications, contraindications, side effects, general assessment, and outlook for the future: An International Compression Club survey.. Phlebology, 2024.
Interventions for varicose veins and leg oedema in pregnancy.. Cochrane Database Syst Rev, 2015.