Compression socks

What compression socks are

Doctors use them for vein problems such as varicose veins and chronic venous insufficiency. Many people also wear them on long flights, on long shifts or after exercise.

• Graduated pressure: Tightest at the ankle and looser up the leg; Cleveland Clinic calls these the most common compression garment.
• Measured in mmHg: Pressure is rated in millimeters of mercury; Cleveland Clinic notes there is no standard scale.
• Socks or stockings: The words overlap: the NHS describes compression stockings as knee-high elastic socks.
• Flight socks: Cochrane uses this name for compression stockings worn through a flight.
• Medical makers: JOBST and SIGVARIS have made medical compression garments since the 1950s.

How they work

Squeezing the calf raises pressure in the tissue under the skin. Cleveland Clinic says this limits fluid buildup and improves blood flow back to the heart.

• Pressure at the ankle: Cochrane says the stockings apply gentle pressure, mostly at the ankle, to help blood flow.
• Helped by movement: With leg movement, that pressure moves blood from surface veins to deep veins and back to the heart, so it is less likely to clot.
• Fewer silent clots: In trials of flights over 5 hours, 50 of 2,637 passengers had a symptomless DVT: 3 wore stockings, 47 did not.
• Less swelling: Passengers in stockings had less leg swelling, though Cochrane rates that evidence low-certainty.
• Well tolerated: Trials that reported side effects found the stockings well tolerated, Cochrane says.

Types

• Graduated compression socks: The common kind for travel and daily wear, tightest at the ankle and looser up the leg.
• Anti-embolism stockings: The other main type; NHS hospitals may give compression stockings to patients more likely to get DVT.
• Sock lengths: Knee-high and thigh-high are the basic lengths; Cleveland Clinic says compression tights and leggings are growing more common.
• Pressure levels: Cleveland Clinic lists mild 8–15, moderate 15–20 and firm 20–30 mmHg; extra-firm 30–40 mmHg is medical grade, usually prescribed.
• Over the counter or prescribed: Cleveland Clinic’s compression therapy guide puts low compression, under 20 mmHg, over the counter and 20 mmHg or more on prescription.
• Sport compression: Some endurance athletes wear them during or after exercise to aid recovery; Cleveland Clinic says some studies support this.

What to look for

• Pressure on the label: Look for the mmHg range; CDC cites a guideline of 15–30 mmHg at the ankle for travelers at increased risk.
• Graduated fit: Pressure should be strongest at the ankle and ease up the leg, MedlinePlus says.
• The right size: For a medical need, Cleveland Clinic advises getting measured and asking your provider for a pressure level.
• The right height: Knee-highs should end about two finger-widths below the bend of the knee, MedlinePlus says.
• A smooth top: The top should not fold over or wrinkle; Cleveland Clinic and NHS guidance both warn against it.
• Easier on: Compression socks can be hard to pull on; MedlinePlus suggests rubber gloves, a little powder or a stocking donner.

On the plane and on the trip

• Four hours or more: CDC says anyone traveling more than 4 hours by air, car, bus or train can be at risk of blood clots.
• Who may benefit: CDC says some travelers may benefit from graduated compression stockings and advises talking to a doctor if you are at risk.
• Not a must for all: Guidelines cited by CDC do not recommend them for travelers without added risk; ASH suggests them for higher-risk trips over 4 hours.
• Keep moving: CDC advises moving your legs often and working your calves; it cites an aisle-seat recommendation, as window-seat passengers had about twice the clot risk.
• After a DVT: The NHS advises delaying flights or long journeys until at least 2 weeks after starting blood-thinning medicine.
• Security screening: TSA asks travelers to tell the officer about a compression sleeve, bandage or dressing before screening; it may get extra checks.
• Washing on the road: Wash them with mild soap and air-dry away from heaters; two pairs let one dry while you wear the other.

Limits and care

• Serious clots untested: No symptomatic DVT, pulmonary embolism or death occurred in the flight trials, so Cochrane could not judge those outcomes.
• When to skip them: Cleveland Clinic advises against wearing them over open wounds, skin infections or very fragile skin.
• Ask first: With peripheral artery disease or reduced feeling in the legs, Cleveland Clinic says to ask a provider first.
• Warning signs: Cleveland Clinic says to call your provider right away for pain, tingling, numbness or skin changes such as redness.
• Know the clot signs: Leg pain and swelling can mean DVT; with breathlessness or chest pain, the NHS says to call emergency services.
• Off at night: Put them on in the morning and take them off before bed; Cleveland Clinic allows the occasional nap in them.
• Replace them: MedlinePlus says to replace them every 3 to 6 months so they keep their compression and support.

A short history

Compression is old medicine. Hippocrates bound leg ulcers with tight bandages, and Galen used wool and linen wraps to keep blood from pooling in the legs.

• 1628: William Harvey links stagnant blood in the veins with outside pressure; laced stockings and elastic bands follow.
• Late 1800s: German doctors Fischer and Lasker find that outside pressure helps treat leg clots, bringing stockings into DVT care.
• 1950: Engineer Conrad Jobst, who had venous disease, founds JOBST in Toledo, Ohio, and develops gradient compression garments.
• 1958–1960: Swiss maker SIGVARIS works with phlebologist Karl Sigg on a medical compression stocking.
• May 2001: A Lancet trial finds symptomless calf clots in 12 of 116 long-haul passengers without stockings, and none in those wearing them.
• June 2007: WHO’s WRIGHT study finds clot risk roughly doubles after 4 hours or more of travel, though it stays low, about 1 in 6,000.
• April 2021: Cochrane updates its review of compression stockings for airline passengers, first published in 2006, to 12 trials.