According to consultants at Chemist Click this is because of a number of causes.

“People who go through extended periods of inactivity, such as during long-distance flights, bed rest due to illness or surgery or being confined to a wheelchair, can increase the risk of deep vein thrombosis - DVT (a blood clot found in a deep vein),” they advised Express.co.uk.

“Immobility, coupled with the reduced cabin pressure and humidity in an aeroplane can contribute to blood pooling and slower blood flow, potentially leading to clot formation or the enlargement of existing clots.

“Flying, particularly long-haul, can increase the risk of pulmonary embolism (PE) which is a serious complication of DVT, when a blood clot breaks off and travels to the lungs causing a blockage because of the prolonged immobility and reduced mobility through the duration.

“The reduced cabin pressure in aeroplanes can lead to dehydration, as the air in the cabin is typically dry.

“Dehydration can thicken the blood, making it more prone to clotting.

“Prolonged sitting without adequate leg movement can contribute to blood pooling in the legs, potentially increasing the risk of clot formation or exacerbating existing clots.”

Signs of a blood clot to look out for when flying

The consultants stated: “Difficulty breathing or a sudden onset of shortness of breath, especially if it is accompanied by chest pain, can be a sign of a pulmonary embolism which is a medical emergency that requires immediate attention.

“Sharp or stabbing chest pain, particularly when accompanied by difficulty breathing, could also be indicative of a PE or other cardiovascular issues.

“If you notice a sudden increase in heart rate or feel irregular heartbeats (palpitations) or feel lightheaded, dizzy or experience a loss of consciousness, you seek medical attention immediately.

“You may have a blood clot if you notice intense pain, swelling or tenderness in one leg, particularly if it is accompanied by warmth, redness, or discolouration.”

Signs of DVT embody:

• Pain and tenderness within the affected leg, typically felt as a deep ache or cramping sensation
• Pain that will worsen when strolling or standing
• Swelling, which can be accompanied by heat and redness, a bluish or purplish hue within the affected space
• Superficial veins close to the positioning of the clot might grow to be extra outstanding and visual.

How to decrease your danger of a blood clot when flying

Luckily there are steps you may take to scale back your danger of a blood clot.

“Take regular opportunities to move and stretch your legs and opt for an aisle seat, if possible,” the consultants added.

“You can do simple leg exercises, such as ankle circles, heel-toe raises and leg lifts while seated.

“Try to walk in the aisle when it's safe to do so or do in-seat exercises to keep your blood flowing.

“Seek advice from your doctor about the appropriate use of the medication during air travel if you're at high risk of DVT and have been prescribed blood-thinning medication.

“Your doctor may also give you aspirin to reduce the risk, and you can also wear compression stockings.

“Sitting with crossed legs can restrict blood flow in the legs. Instead, keep your legs uncrossed and your feet flat on the floor or supported on a footrest if available.”

Other danger elements for blood clots embody if you happen to:

• Are staying in or just lately left hospital – particularly if you happen to can not transfer round a lot
• Are chubby
• Smoke
• Are utilizing mixed hormonal contraception
• Have had a blood clot earlier than
• Are pregnant or have simply had a child
• Have an inflammatory situation reminiscent of Crohn’s illness or rheumatoid arthritis.

If you might be involved that you would have a blood clot you need to communicate to your GP.