How to prevent blood clots during long trips and flights

You’ve made your reservations and packing list, and you’re ready to take off on your next adventure. But if your trip includes long-distance travel, you may wonder if deep vein thrombosis (DVT) prevention should be part of your plan, too.

Sitting for long periods of time slows blood flow in the legs, which increases the risk of a blood clot forming deep in a vein, called DVT. Some blood clots may break off and travel to your lungs, which can potentially cause a dangerous pulmonary embolism (PE).

While it’s common to worry about blood clots and flying—especially if you have risk factors— there’s no reason to cancel your next flight. DVT risk rises about two- to five-fold when your flight is more than four to eight hours, but the absolute risk of DVT with long-distance flying is still less than 1%. And with the right preventive steps, you can safely minimize your risk and enjoy your trip.

From in-flight movements and compression stockings to common myths and symptoms, get the actionable tips you need to reduce the risk of blood clots and feel confident on your next trip.

How to prevent blood clots when traveling

When traveling a long distance, blood clot prevention is a good idea for everyone—even if you’re young and don’t have any medical conditions. No matter your risk factors, focus on regular movement and hydration to improve blood flow. 

If you have known risk factors or are concerned about your risk, talk to your doctor about other prevention options, such as graduated compression stockings or medications.

In-flight and car movement strategies

Any activities with prolonged sitting in a confined space increase the risk of DVT. Bent knees can reduce blood flow in the veins, and gravity also pools blood in the lower legs. That’s why frequent movement when traveling is the most effective prevention method.

Take these simple steps to reduce your DVT risk through walking and movement:

• Pick an aisle seat on your flight, making it easy to get up and walk for two minutes every one to two hours.
• Avoid putting direct pressure on the back of the knees. Leave a small gap between the front edge of your seat and the back of your knees.
• When getting up frequently isn’t feasible, calf rise and ankle rolling exercises can also help. Do 10 slow calf rises every 30 minutes.
• Avoid sitting with legs crossed and keep your knees bent at less than 90-degree angles.
• Avoid putting heavy objects, such as large laptops or backpacks, on top of your thighs.

Hydration

Dehydration contributes to clot formation in multiple ways. It can cause your blood to thicken and flow less easily, injure the inner lining of your blood vessels, and trigger the release of pro-clotting factors, such as fibrinogen and vWF. So staying hydrated is important to keeping your blood flowing as it should.

When taking a long-distance flight, set yourself up for hydration success by:

• Filling your water bottle at the gate and keeping it by your side after boarding.
• Choosing water instead of high-calorie and high-sodium drinks when food or drink services are offered.
• Avoiding drinking alcohol. Alcohol reduces the release of a hormone in your body that helps maintain your fluid levels.

Compression socks

For people with an average risk of blood clots or DVT, movement and hydration are the main recommendations. But if you have a higher risk, the American College of Chest Physicians recommends graduated compression stockings (GCS). GCS squeezes blood from the superficial veins to the deep venous system, which increases the speed at which your blood flows, helping reduce clot formation.

Here’s what you should know about choosing compression socks:

• The decision to wear GCS is different for each person. Talk to your doctor about compression socks and other preventive methods before a long trip.
• Compression stockings are only beneficial when they fit properly. If your doctor recommends GCS, medical supply stores or specialty vein/edema clinics have the trained expertise to help.
• Compression stockings are available in different pressure levels. If you have a moderate risk of developing a blood clot (DVT), over-the-counter compression stockings with 15-20 mmHg of pressure may be appropriate. If you have a higher risk, your doctor may prescribe graduated compression stockings that provide stronger pressure, typically 20-30 mmHg or 30-40 mmHg.

What NOT to do: Aspirin and supplement myths

One common misconception is that taking an aspirin before a long flight prevents blood clots. But the evidence of the benefit of aspirin use before a flight for DVT prevention is not well established.

As a result, both the American College of Chest Physicians and Centers for Disease Control and Prevention advise against routine aspirin use for the general population for this purpose. But, certain groups of people may benefit from aspirin or blood thinner prophylaxis before their flights. Talk with your doctor about your options.

There’s also no evidence that specific supplements or vitamins are effective in DVT prevention.

Blood clots and flying: Who is most at risk?

When it comes to blood clots and long flights, your risk can increase depending on your health history or certain medical conditions. Talk to your doctor if you have factors that put you at a higher risk for DVT when flying.

Risk factors include:

• Personal history of DVT or pulmonary embolism
• Recent major surgery
• Active cancer diagnosis or undergoing cancer treatment
• Current estrogen or testosterone use
• Body mass index (BMI) greater than 30 kg/m2
• Medical conditions that make your blood more likely to clot
• Over 65 years old
• Uncontrolled diabetes or high blood pressure

If you’re a frequent flyer—even if you’re young and have no risk factors—that’s important, too. Your risk may be 1 in 1,000, but if you take hundreds of flights, by chance, you may be more likely to experience flight-related DVT.

Most young adults without any significant medical conditions are considered low risk. The incidence is very low in travelers who are younger than 45, but the estimated number of flight-triggered DVT cases can reach the 100 range per day in the United States. So basic preventive steps, including frequent movement, are still key, no matter how low your risk.

Recognizing travel blood clot symptoms

Once you’re at your destination, the risk of travel-related blood clots can linger. Elevated risk persists for roughly four to eight weeks after long-haul travel, but it’s concentrated in the first one to two weeks. After your trip, know the signs that need attention so you can get the care you need quickly.

Signs of deep vein thrombosis (DVT)

If you have signs of DVT, make an appointment with your primary care physician to get checked. Your doctor can order imaging to confirm if your symptoms are caused by DVT and work with you to create a treatment plan.

DVT symptoms include:

• Swelling in one or both legs
• Localized leg pain or cramping, often in the calf
• Skin warmth or redness
• A shoe suddenly feeling tight or longer fitting comfortably

Signs of pulmonary embolism

If you have signs of pulmonary embolism (PE), call 911 immediately. PE happens when a blood clot, usually in your legs, breaks off and travels to the lungs, blocking blood flow. It needs emergency care.

PE symptoms include:

• Sudden shortness of breath
• Chest pain when breathing deeply
• Rapid heart rate
• Lightheadedness
• Coughing up blood or blood-tinged mucus

Simple steps for peace of mind

While long-distance travel increases the risk of blood clots and DVT, you have the tools you need to take control of your risk. Simple steps like frequent movement, hydration and talking with your doctor if you have risk factors can set you up for a smoother trip ahead.

Planning a long trip or managing high-risk medical factors? Learn more about deep vein thrombosis and schedule a visit with a primary care provider at Baylor Scott & White Health today.