Flying for long hours comes with a well-known health concern: the risk of blood clots. For years, travelers have been advised to consider wearing compression socks to mitigate this risk. But are Travel Circulation Socks truly essential, or is it just another travel myth?
According to Dr. Joshua Beckman, a vascular medicine expert at UT Southwestern Medical Center, “It’s perfectly fine to use them.” However, he points out that scientific evidence doesn’t definitively quantify how much these socks benefit air travelers.
Travel circulation socks, also known as graduated compression socks, are designed to apply pressure at the ankle and gradually reduce it up the leg. This compression is intended to promote healthy blood flow, encouraging blood in the legs to return to the heart more efficiently.
Deep vein thrombosis (DVT), a condition involving blood clots in large veins, often in the legs, affected an estimated 666,000 people in the U.S. in 2020, as per the American Heart Association. Pulmonary embolism, a related condition where a clot travels to the lungs, led to 432,000 hospitalizations in the same year. Venous thromboembolism (VTE), encompassing both DVT and pulmonary embolism, was cited as a factor in nearly 81,000 deaths in 2021.
Symptoms of DVT can include leg pain, swelling, and unusual warmth in the skin. Pulmonary embolism may manifest as shortness of breath, coughing, and chest pain.
Research indicates that long-haul flights can increase the likelihood of VTE by 1.5 to four times, as highlighted in a 2021 Cochrane Database of Systematic Reviews study.
Despite the increased risk associated with flying, the occurrence of severe blood clots remains relatively low. A 2007 study in the Journal of Internal Medicine estimated about 4.8 severe pulmonary embolism cases per million flights exceeding 12 hours. The risk of DVT within four weeks of a flight of at least four hours was found to be approximately 1 in 4,600 flights.
Dr. Eri Fukaya, a vascular medicine specialist at Stanford University, notes that flying can indeed create conditions conducive to blood clot formation. However, she emphasizes that individual risk factors play a more significant role.
Factors such as older age, smoking, obesity, and a family history of blood clots elevate VTE risk. Similarly, individuals with a history of blood clots, recent cancer treatment, or estrogen use are also at higher risk.
Dr. Fukaya uses an analogy of a bucket to explain risk accumulation. People with pre-existing risk factors have a fuller “bucket,” making them more susceptible to overflow – in this case, a blood clot – when exposed to triggers like air travel.
Prolonged immobility, typical of long flights in confined spaces, contributes to the risk, explains Dr. Fukaya. Dehydration, often exacerbated by flyers limiting fluid intake to avoid frequent bathroom breaks, can further thicken the blood and increase risk.
However, Dr. Beckman emphasizes that the risk of developing serious blood clots solely due to flying is so minimal that studying preventative measures becomes challenging.
He references a 2022 study in the American Journal of Obstetrics and Gynecology: Maternal-Fetal Medicine, which focused on pregnant and postpartum women, a group considered at higher risk for VTE. While the study showed a slightly elevated risk of VTE in women who flew compared to those who didn’t (0.07% vs. 0.05%), Dr. Beckman points out that the difference is “very tiny.”
These minute differences underscore the difficulty in definitively proving the effectiveness of travel circulation socks in preventing blood clots for air travelers. “If the risk is really low, and you go from really low to really, really low, you can’t have enough people in a study to actually figure it out,” Dr. Beckman explains.
The Cochrane review, analyzing data from 2,918 participants across 12 clinical trials, found strong evidence that compression stockings reduce the risk of asymptomatic DVT during flights longer than four hours. However, the review couldn’t draw conclusions about the impact on death risk, pulmonary embolism, or symptomatic DVT due to the absence of these outcomes in the trials.
Guidelines from the American Society of Hematology do not recommend travel circulation socks for low-risk individuals on short flights. For longer flights, they are only suggested for those at high risk of blood clots.
Dr. Beckman acknowledges hospital studies demonstrating the effectiveness of compression socks in preventing blood clots for post-surgical patients. However, he notes that the benefits are less clear for non-surgical patients on bed rest. He suggests that if establishing a clear benefit is difficult even for hospitalized patients, proving efficacy for healthy, mobile travelers on planes or cars is even more challenging.
Nevertheless, Dr. Beckman stresses that if a doctor recommends wearing travel circulation socks for any reason, it’s crucial to follow that advice.
For travelers concerned about blood clots, Dr. Beckman’s primary advice is simple: “get up and walk every couple of hours. Drink lots of water.”
Dr. Fukaya supports this advice and adds the importance of seated exercises. She recommends flexing calf muscles and making “big circles” with ankles in both directions. She also suggests removing shoes and wiggling toes to further stimulate blood flow.
For those already using and benefiting from travel circulation socks, there’s no need to stop.
Dr. Fukaya, although acknowledging the limited definitive scientific proof for air travel specifically, is personally a proponent of compression socks and wears them regularly.
She points out the long history of compression therapy, dating back to ancient times, and highlights that these socks can stimulate calf muscles during movement and help prevent swelling.
“I wear them almost every day,” Dr. Fukaya states, explaining that she started wearing them to better understand her patients’ experiences and found her legs felt significantly better.
While caution is advised for individuals with poor circulation due to peripheral artery disease, Dr. Fukaya encourages others to experiment and find what works best for them.
The market offers a wide range of compression socks, from those marketed for athletes to medical-grade options. Medical-grade socks are rated by pressure in millimeters of mercury, but Dr. Fukaya finds these ratings less crucial, citing variations based on leg size and lack of standardized regulation.
She likens choosing compression levels to ordering food spice levels: “mild, medium, or spicy?”. She suggests starting with a medium compression level and adjusting based on comfort. Trying different compressions on each leg can also help determine personal preference. Dr. Fukaya recommends knee-high socks over thigh-high versions and advises against rolling down knee-high socks if they are too long, as it can create a tourniquet effect.
Dr. Beckman concludes that while travel circulation socks are acceptable for those who find them comfortable, focusing on broader health measures is more critical for safe travel. Prioritizing actions like using sunscreen is also important.
He emphasizes the importance of focusing on impactful health practices and avoiding unnecessary anxieties. “There are so many things that people have to think about” for health protection, he says. “It’s also important to get them to not have to think about things they don’t need to think about.”
