Can long flights increase the risk of pulmonary embolism? 

Long-haul travel, particularly flights lasting more than several hours, is a recognised factor that can increase the likelihood of developing blood clots. This risk arises primarily from the extended periods of immobility associated with sitting in a confined space, which can slow blood circulation in the lower limbs. Understanding how travel impacts your vascular health and taking simple preventative steps can significantly help in managing these risks and ensuring a safer journey. 

What We’ll Discuss in This Article 

• The link between immobility during travel and blood clot formation. 

• Why long-distance flights specifically pose a risk to your circulation. 

• Identifying individuals who may be at a higher risk of travel-related clots. 

• Practical preventative measures to take before and during your flight. 

• The importance of hydration and movement while in the air. 

• Recognising the symptoms of a potential clot after you have landed. 

The connection between long flights and blood clots 

Long flights increase the risk of pulmonary embolism because sitting still for extended periods can cause blood to pool in the deep veins of the legs. This condition, known as deep vein thrombosis, can lead to a pulmonary embolism if a piece of the clot breaks off and travels through the bloodstream to the lungs. The NHS explains that the risk of a blood clot is higher if you are sitting still for more than 3 or 4 hours, such as on a long flight, train, or car journey. 

How immobility affects the vascular system 

When you are stationary for a long time, the muscles in your legs are not contracting to help pump blood back toward your heart, which can cause the flow to become sluggish. In the pressurized cabin of an aircraft, other factors like lower humidity and potential dehydration can also contribute to making the blood slightly more prone to clotting. While the absolute risk for a healthy person remains low, the combination of physical restriction and environmental factors makes it essential to stay mindful of your leg health during the flight. 

Identifying high-risk travellers 

While anyone can develop a clot during a long journey, certain factors can make some individuals much more susceptible than others. People who have a personal or family history of blood clots, those who have recently had surgery, or individuals with active cancer are considered to be at a significantly higher risk. NICE clinical guidance suggests that healthcare professionals should assess risk factors such as pregnancy, use of hormonal contraceptives, and obesity when advising patients on travel safety. 

Risk Factor	Reason for Increased Risk
Previous History	Existing damage to veins or genetic clotting tendencies.
Recent Surgery	Body is naturally in a pro-clotting state during healing.
Pregnancy	Changes in blood chemistry and pressure on pelvic veins.
Hormone Therapy	Certain medications can increase the blood’s ability to clot.

Preventative measures for long-haul travel 

There are several evidence-based steps you can take to reduce the risk of a blood clot forming while you are in the air. Simple leg exercises, such as flexing your ankles and extending your legs while seated, help to stimulate the “muscle pump” that moves blood through the veins. Additionally, walking up and down the aisle whenever it is safe to do so provides the necessary movement to keep your circulation active and prevent the blood from pooling in your lower limbs. 

The role of hydration and compression 

Staying well-hydrated by drinking plenty of water and avoiding alcohol or excessive caffeine is a vital part of travel safety, as it helps prevent the blood from becoming too thick. For those at moderate or high risk, a doctor may recommend the use of graduated compression stockings, which apply gentle pressure to the ankles and calves to help the blood flow more efficiently. In specific high-risk cases, a medical professional might even prescribe a one-off dose of preventative blood-thinning medication before a long-distance trip. 

Conclusion 

Long flights do increase the risk of pulmonary embolism due to the prolonged immobility involved in long-distance travel. By understanding your personal risk factors and making a conscious effort to move and stay hydrated, you can significantly lower the chance of a blood clot developing. Most travel-related clots are preventable with these simple, proactive measures. If you experience severe, sudden, or worsening symptoms, call 999 immediately. 

Authority Snapshot (E-E-A-T Block) 

This article was created by the MyPatientAdvice Medical Content Team and reviewed by Dr. Stefan Petrov to provide safe, evidence-based information for travellers. The content is strictly aligned with the clinical standards and public health guidance provided by the NHS and NICE regarding venous thromboembolism. Our goal is to help the public understand the risks of long-distance travel and the importance of simple preventative actions to maintain vascular health.