Texas vascular surgeon explains the physiological effects of flying on an airplane; shares 3 tips to prevent blood clots

Flying on an airplane is more than just sitting for long hours - it can silently raise your risk of getting blood clots. Dr Malik shares 3 tips to prevent them.

Flying might feel like nothing more than hours of sitting and waiting, but inside the cabin, your body is dealing with conditions that can quietly increase the risk of blood clots. From prolonged immobility to dehydrating air and altered cabin pressure, air travel creates a perfect storm that slows blood flow - especially in the legs. The good news is that a few simple, practical strategies can go a long way in protecting your circulation and reducing this risk while you’re in the air.

Dr Rema Malik, a Houston-based vascular surgeon and health educator, is breaking down how flying affects the body’s physiology and sharing practical steps you can take to reduce the risk of blood clots while travelling. In an Instagram video shared on December 23, 2025, the vascular surgeon highlights, “While you are stressing about packing gifts and catching connections, your body is fighting a different battle inside that pressurised tube. ​As a vascular surgeon, I don't worry about the turbulence outside the plane. I worry about the ‘turbulence’ happening inside your veins.”

How does flying affect the body?

She states, “When the cabin door closes, you enter a ‘3-Hit Combo’ environment perfectly designed to create a blood clot (DVT).” They are as follows:

The seat

Sitting for long hours on a plane leads to circulation stagnation, effectively switching off the calf muscles - which Dr Malik refers to as the body’s “second heart” because of their crucial role in pumping blood back towards the heart. The vascular surgeon explains, “Prolonged sitting shuts down your ‘Second Heart’ (your calf muscles). Without movement, blood stops pumping up and starts pooling down.”

The air

According to Dr Malik, the air inside an aeroplane cabin is extremely dehydrating, which can thicken the blood and make clot formation more likely. She explains, “Cabin air is drier than the Sahara Desert. This rapidly dehydrates you, making your blood physically thicker and sludgier. Thick blood clots faster.”

The pressure

Aeroplane cabins are tightly pressurised environments, and the lower cabin pressure can cause blood vessels to dilate, disrupting normal valve function and impairing healthy blood flow. The vascular surgeon highlights, “Lower cabin pressure causes your veins to expand (dilate). This stretches the valves, making them less efficient at fighting gravity.”

Precaution tips

Dr Malik outlines three simple yet crucial precautionary measures that can help reduce the risk of blood clot formation during flights. She emphasises, “​This isn't about comfort. It's about safety. Whether you are 25 or 65, here is your "In-Flight" Vascular Protocol.”

Compression socks

Dr Malik recommends wearing compression socks like it’s your armour during flights, as they significantly improve blood flow from the calves back to the heart and help counteract circulation stagnation. She stresses, “Compression socks (15-20 mmHg) are non-negotiable. They mechanically force blood flow and prevent swelling. Put them on before you leave the house.”

Drink water

The vascular surgeon advises drinking at least eight ounces of water for every hour you’re in the air, as staying well hydrated helps maintain healthy blood viscosity and reduces the risk of clot formation. She explains, “Drink 8oz of water for every hour you are in the air. Coffee and wine don't count (they dehydrate you further).”

Ankle pumps

Dr Malik advises doing simple ankle pumps every 30 minutes, as this activates the calf muscles, boosting circulation and helping prevent blood clots from forming. She recommends, “Every 30 minutes, do 30 ankle pumps. Pretend you are pressing a gas pedal. This manually fires the calf muscle to clear stagnant blood.”

Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. It is based on user-generated content from social media. HT.com has not independently verified the claims and does not endorse them.