Deep Vein Thrombosis (DVT)

Sitting for long periods, particularly for over five hours in an aircraft, bus, train or car, can lead to a condition called deep vein thrombosis, or DVT. The combination of cramped seating, immobility, dehydration and reduced oxygen pressure at high altitude can cause blood clots to form, typically in the veins of the legs. If a piece of a clot breaks off and travels to the lungs, the consequences can be severe, even fatal.

Risk Factors

Some travellers are more at risk of DVT than others, particularly those who:

  • have had DVT previously
  • have a family history of blood clots
  • have a known clotting disorder
  • are smokers
  • are overweight or obese
  • are pregnant
  • are aged 40 or older
  • have major varicose veins
  • have had surgery recently
  • have cancer or are receiving cancer treatment such as chemotherapy
  • have systemic lupus erythematosus (SLE)
  • use an oestrogen-containing contraceptive pill or hormone replacement therapy
  • have a serious medical condition, such as congestive heart failure or inflammatory
  • bowel disease.

Prevention

Travellers who have previously had a DVT may be advised to take anticoagulant medication before the flight to reduce their risk.

To prevent DVT, you are also advised to:

  • Exercise your calf muscles and stretch your legs while you're sitting.
  • Stand up and walk occasionally.
  • Avoid sitting with your legs crossed.
  • Drink plenty of water or juice during the flight to maintain hydration.
  • Avoid excessive alcohol, tea or coffee as they cause dehydration.
  • Wear properly fitted compression stockings if you are at a high risk of DVT or tend to
  • suffer from leg swelling during flights. Compression stockings improve blood flow
  • from the legs and prevent swelling.