Deep Vein Thrombosis Prevention While Flying: A Complete Guide for Older Travellers

What Is Deep Vein Thrombosis and Why Does Flying Increase Your Risk?

Deep vein thrombosis, commonly known as DVT, occurs when a blood clot forms in a deep vein, most often in the legs. When you sit still for long periods, blood pools in the lower limbs rather than circulating freely back to the heart. The confined space of an aeroplane seat, the low cabin humidity, and the reduced oxygen levels all add to the conditions that can encourage clot formation.

DVT itself can cause pain and swelling, but the greater danger arises if a clot breaks loose and travels to the lungs, causing a pulmonary embolism. This is a potentially life-threatening event that requires immediate emergency care. Understanding the risk and taking preventive steps is therefore not merely advisable but genuinely important, particularly for older travellers.

The risk of developing a clot associated with air travel roughly doubles on flights lasting four hours or more, according to research from the World Health Organisation. For older adults, that baseline risk is already higher than it is for younger people, making awareness and preparation essential before any long journey.

Why Older Adults Face a Higher Risk

Age brings a number of physiological changes that raise the likelihood of clot formation. Blood naturally becomes more prone to clotting as we get older, partly because the walls of veins become less elastic and the valves that help push blood upward become weaker. Circulation slows, and the muscles in the legs, which act as a pump when you walk or move, are often less active.

Several common health conditions in older adults further increase DVT risk. These include heart disease, cancer, varicose veins, previous clots, obesity, and recent surgery. Some medications, including hormone replacement therapy and certain treatments for heart conditions, can also affect clotting. If you take any regular medication, it is worth speaking with your GP or doctor before a long flight to understand your personal risk level.

Dehydration is another contributing factor. Older adults are more susceptible to becoming dehydrated, and the dry air inside an aircraft cabin can draw moisture from the body quickly. Dehydrated blood is thicker and more likely to clot, which is one reason why drinking enough fluids during a flight is one of the simplest and most effective preventive measures available.

Knowing Your Personal Risk Before You Fly

Before any long-haul journey, it is a good idea to assess your individual risk. A conversation with your GP or travel health nurse is particularly worthwhile if any of the following apply to you:

• You have had a previous blood clot or pulmonary embolism
• You or a close family member have a known clotting disorder
• You have had recent surgery, particularly to the hips, knees, or abdomen
• You have active cancer or are receiving cancer treatment
• You are significantly overweight
• You have heart failure or serious heart disease
• You use hormone replacement therapy
• You have limited mobility in your legs

Your doctor can advise whether you need any additional precautions, such as blood-thinning medication before flying, or whether certain journeys carry a risk that outweighs the benefit for your specific situation.

Compression Stockings: One of the Most Effective Tools

Graduated compression stockings, sometimes called flight socks, are widely recommended by healthcare professionals for long-haul travellers, and particularly for older adults or anyone with risk factors. These stockings apply more pressure at the ankle than at the calf, which encourages blood to flow upward rather than pool in the lower leg.

They come in different levels of compression, typically measured in millimetres of mercury (mmHg). For most travellers, socks in the 15 to 30 mmHg range provide good protection without being uncomfortably tight. If you have a medical history that puts you at higher risk, your doctor may recommend prescription-grade compression stockings with a higher compression rating.

It is important to choose the right size. Too loose and they provide little benefit; too tight and they can restrict circulation rather than support it. Most pharmacies and medical supply shops will measure your leg and recommend the correct size. Put the stockings on before you board, ideally in the morning before your legs have had time to swell, and wear them for the entire duration of the flight.

People with peripheral arterial disease should consult a doctor before using compression stockings, as increased pressure can sometimes be harmful in that condition.

In-Flight Exercises to Keep Blood Moving

Even in a cramped airline seat, there are exercises you can do to stimulate circulation in your legs. Making a habit of these movements every hour or so during a long flight makes a real difference.

Ankle circles: Lift your feet slightly off the floor and slowly rotate your ankles in wide circles, first clockwise then anticlockwise. This activates the calf muscles and encourages blood flow.

Heel raises: Keep your toes on the floor and raise your heels as high as you can, then lower them again. Repeat ten to fifteen times. This movement directly engages the calf muscle pump.

Toe raises: Reverse the motion by keeping your heels on the floor and lifting your toes toward your shins. Alternate with heel raises for a full calf workout.

Knee lifts: Slowly raise one knee toward your chest, hold for a few seconds, then lower it. Alternate legs. This gets blood moving through the thighs as well as the calves.

Standing and walking: If the seat-belt sign is off and the cabin crew confirm it is safe, get up and walk the length of the aisle every hour or two. Even a short walk makes a considerable difference to circulation.

Aim to do these exercises for two to three minutes every sixty minutes. Setting a quiet alarm on your phone or watch can help you remember.

Hydration: Simple and Effective

The air inside an aircraft cabin is extremely dry, often with a humidity level of around 10 to 20 per cent, far lower than the 40 to 60 per cent most people find comfortable indoors. This dry environment causes the body to lose moisture more quickly than usual, and dehydration thickens the blood, increasing clot risk.

Drinking water regularly throughout the flight is one of the easiest things you can do. A good general guideline is to drink at least 250 millilitres of water for every hour in the air. Accept water when the cabin crew offer it and do not rely solely on feeling thirsty, as thirst signals can diminish with age.

Avoid alcohol and caffeinated drinks such as coffee during the flight. Both have a diuretic effect, meaning they cause the body to lose more fluid than they supply. A glass of wine at altitude may feel relaxing, but it contributes to dehydration and can increase fatigue.

What to Wear on the Plane

Clothing choices matter more than many travellers realise. Tight waistbands, belts, or trousers that constrict at the hips or thighs can restrict blood flow from the legs back to the heart. Loose, comfortable clothing in breathable fabrics is better suited to long-haul travel.

Avoid crossing your legs for extended periods, as this can compress the veins in the back of the knee and impede circulation. Keep your feet on the floor or on a small footrest rather than tucked under you.

Shoes tend to swell during long flights due to fluid retention in the feet. Slip-on shoes or adjustable footwear that can be loosened during the journey are far more comfortable and less likely to contribute to circulation problems than tight-fitting shoes.

Seat Selection and Positioning

Where you sit on the plane can affect your ability to move freely and reduce your DVT risk. An aisle seat gives you easier access to stand and walk without disturbing other passengers. Window seats, while offering more privacy, can make it psychologically harder to get up frequently.

Some airlines offer extra legroom seats near emergency exits or at the front of economy class. The additional space makes it easier to stretch your legs and perform exercises. If you fly regularly and are concerned about DVT, it may be worth paying for the upgrade.

Recline your seat when trying to sleep, as a slightly reclined position reduces the pressure on the backs of your thighs compared to sitting bolt upright. However, fully reclined seats can make it harder to shift position and get up, so find a comfortable middle ground.

Medication Considerations

For people assessed as being at high risk of DVT, doctors sometimes prescribe low-molecular-weight heparin injections, which are given before a long-haul flight to thin the blood temporarily. This is not a routine measure and should only be undertaken on specific medical advice.

Aspirin is sometimes suggested as a preventive measure, but current clinical guidance does not support its routine use for travel-related DVT prevention. Aspirin carries its own risks, particularly for older adults with certain health conditions, and should only be taken for this purpose if explicitly recommended by your doctor.

If you already take anticoagulant medication such as warfarin or a newer blood thinner like rivaroxaban, speak with your doctor before flying to confirm your current dose is appropriate and whether any adjustments are needed for a long journey.

Recognising the Symptoms of DVT

Despite taking all precautions, it is important to know what DVT looks and feels like so that you can seek prompt medical attention if needed. Symptoms typically develop in one leg rather than both, and may include:

• Pain or tenderness in the calf, thigh, or behind the knee
• Swelling in one leg, ankle, or foot
• Warmth and redness over the affected area
• A heavy, aching feeling in the leg

Symptoms can appear during a flight or in the hours and days after landing. If you notice any of these signs, seek medical evaluation promptly. Do not dismiss leg pain as simple muscle stiffness.

When Symptoms May Signal a Pulmonary Embolism

If a blood clot breaks off and travels to the lungs, the resulting pulmonary embolism is a medical emergency. Symptoms include sudden shortness of breath, chest pain that worsens when breathing deeply, a rapid heart rate, lightheadedness or fainting, and coughing up blood. If you experience these symptoms at any point after a long flight, call for emergency medical help immediately.

After You Land: Keep Moving

The risk of DVT does not end the moment the plane touches down. Blood can continue to pool in the legs for several hours after a long journey, particularly if you then sit for an extended period in an airport, transfer vehicle, or at your accommodation.

Try to walk as soon as possible after landing. If you have a long connection, walk the terminal rather than sitting at the gate. Once you reach your hotel, continue to move regularly and drink plenty of water. Continue wearing your compression stockings for several hours after landing, as the risk period extends beyond the flight itself.

Preparing Well Makes a Real Difference

DVT is a preventable condition in the vast majority of cases, and the steps involved are straightforward. Wearing compression stockings, exercising your legs regularly during the flight, staying well hydrated, and speaking with your doctor before long journeys if you have relevant health conditions are all effective measures that significantly reduce your risk.

Older adults who travel frequently should build these habits into their routine as standard practice. The goal is to arrive at your destination feeling well and ready to enjoy your trip, not to spend the first days recovering from the effects of a preventable health problem.