Can Aspirin Help Prevent Blood Clots During Long Flights? Expert Opinions Share Insights.

If you've taken a long-haul flight, you've likely encountered discussions about deep vein thrombosis (DVT)—blood clots that commonly form in the calves and are linked to air travel. These clots can move to the lungs, leading to potentially fatal blockages called pulmonary embolisms.

DVT is especially relevant during lengthy flights, defined as those lasting four hours or more. According to Dr. Lin Chen, director of the Travel Medicine Center at Mount Auburn Hospital in Cambridge, Massachusetts, and an associate professor at Harvard Medical School, the greater risk occurs with flights that extend beyond eight hours.

This alarming information prompts many travelers to consider taking aspirin, recognized for its blood-thinning effects, before boarding. But is aspirin genuinely effective in this scenario?

What factors contribute to the occurrence of deep vein thrombosis during flights?

Flight-associated DVT is mainly thought to arise from limited movement—a significant issue given the reduced legroom in airplanes, particularly in economy class over the years.

"Unlike arteries, which are actively pumped by the heart," explains Dr. Danielle R. Bajakian, a vascular surgeon at New York-Presbyterian/Columbia University Irving Medical Center and director of the Columbia Vein Program, "veins rely on calf muscle contractions to circulate blood. Thus, a lack of movement leads to blood pooling in the veins."

Bajakian points out that the likelihood of forming blood clots after a long flight is approximately one in 5,000. She also discusses a theory regarding another factor contributing to DVT: "With the differing air pressure in airplanes—comparing cabin pressure to outside pressure—there’s potentially reduced oxygen in the blood, which could theoretically elevate the risk of clots." This theory remains a topic of debate.

Moreover, certain individual factors can heighten the risk, such as obesity, pregnancy, being over 40, recent orthopedic surgeries, use of contraceptives or hormone therapy, active cancer, and a personal history of DVT.

Does taking an aspirin before a long flight help prevent blood clots?

The jury is still out. According to its website, the Centers for Disease Control and Prevention (CDC) does not advise taking aspirin before a long flight to prevent blood clots. Both Bajakian and Chen emphasize this stance due to insufficient evidence supporting aspirin's effectiveness for travelers.

"Some doctors might suggest it, but that recommendation isn’t backed by significant studies," Bajakian explains. "The information stems from orthopedic literature, where aspirin is indicated for DVT prevention in hip surgery patients. However, there’s no concrete data supporting its use for preventing blood clots during travel."

Chen mentions that while she doesn't advocate for aspirin use before long flights, she remains open to it for patients without specific health concerns (like an aspirin allergy or gastrointestinal bleeding risks). She advises travelers, "If someone asks, 'Should I take aspirin for an upcoming long-haul flight?' I’d inform them that guidelines don’t indicate it prevents DVT, but if there are no contraindications, I won't categorically advise against it."

Depending on individual risk factors and medical history, doctors may prescribe anticoagulants such as injectable low molecular weight heparin or oral alternatives before a long flight. However, just like with aspirin, these medications should only be used under medical supervision as a preventive measure.

What other strategies can travelers employ to avoid blood clots?

The positive aspect is that travelers can reduce their risk of DVT without relying on medication. If you're able, it's beneficial to stroll up and down the aisle; Bajakian recommends doing this at least once every hour if you can. Performing calf exercises while seated is also helpful, which is why Bajakian advises keeping your belongings in the overhead bins rather than under the seat to maximize your legroom. Staying hydrated, wearing compression socks, and steering clear of sedatives that might keep you seated are additional strategies to consider.

Although these recommendations are usually targeted at travelers with a higher risk of DVT, "I strongly advocate for these practices for anyone embarking on a long flight," states Bajakian.