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Preventing thrombosis

NHS Choices Medical Reference

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It is not possible to prevent thrombosis altogether, but there are a number of ways to minimise the risks of developing a blood clot in a vein or artery.

Whatever your risk of developing thrombosis is, you can help to reduce it by following the lifestyle advice below. As well as reducing your risk of thrombosis, you can improve your overall health by:

  • not smoking,
  • eating a healthy, balanced diet (low in fat and sugar, and high in fruit and vegetables),
  • getting regular exercise, and
  • maintaining a healthy weight (losing weight if you are overweight or obese).

If you smoke, the most important and positive thing that you can do for your health is to quit.

To find out if you are overweight or obese, you can use the body mass index (BMI) calculator (see Useful links).

Increased risk of thrombosis

Some people have an increased risk of developing a blood clot in a vein or artery, and may need to make changes to reduce it.

If you have a higher-than-normal risk of developing venous thrombosis, you may need to go into hospital and take medicine in order to reduce the risk of a blood clot occurring. 

Similarly, if you are at risk of developing arterial thrombosis, it is important to take steps to reduce it, either to prevent a previous arterial blood clot from coming back, or to prevent one occurring in the first place.

Preventing venous thrombosis in hospital

If you need to be admitted to hospital, your healthcare team will assess your risk of developing a blood clot while you are there.

This is because just being in hospital increases your risk of developing a blood clot. This risk is increased if you are having surgery, particularly if it is to the lower half of your body.

Severe injuries or surgery itself may cause damage to your blood vessels, and being inactive while in hospital causes your blood flow to reduce, both of which can make a blood clot more likely to occur.

You may be considered as having an increased risk of blood clots if you:

  • are over 40 years of age,
  • are due to have a general anaesthetic or due to have surgery on your abdomen, hips or legs,
  • have had a previous blood clot,
  • have family members who have had a blood clot,
  • are overweight or obese,
  • have ever had cancer, or
  • have problems with your heart, lungs, bowel or joints.

If any of the above applies to you, your healthcare team may recommend that you take an anticoagulant medicine while you are in hospital, and for a while after you go home.

Anticoagulant medicines, such as heparin or warfarin, thin your blood so it is less likely to form a clot within a vein. See the Treatment section for information about anticoagulant medicines.

You may also need to wear compression stockings and use compression devices during your stay in hospital, and for some time afterwards.

Compression stockings are worn around your feet, lower legs and thighs, and fit tightly to encourage your blood to flow more quickly around your body. Compression devices are inflatable, and work in the same way, inflating at regular intervals to squeeze your legs and encourage blood flow.

Once you are well enough, it is important that you try to move around or do leg exercises as soon as possible. Also avoid taking long journeys for four weeks after you come out of hospital.

Preventing arterial thrombosis

If you have had a previous blood clot in an artery, you may need to take medicines to prevent it from happening again.

For example, if you have had a heart attack that was caused by a clot in an artery that supplies your heart, you may need to take statins (to lower your cholesterol level), or anti-platelet medicines (to make your blood less likely to clot).

See the Treatment section for more information about treatments following arterial thrombosis.

In addition to these medicines, it is vital that you look after your health and take steps to improve your lifestyle. Most cases of arterial thrombosis are associated with atherosclerosis, and making healthy changes to your lifestyle can greatly reduce the effects of this condition.

This is also important if you have a condition such as heart disease or atherosclerosis (the 'furring up' of your arteries with fatty deposits), which can lead to a blood clot in an artery and cause a heart attack or stroke.

In order to reduce your risk of developing heart disease and other associated conditions, such as arterial thrombosis, the National Service Framework (NSF) on coronary heart disease gives the following advice:

  • don't smoke,
  • reduce the amount of salt and fat that you eat (particularly saturated fat),
  • eat at least five portions of fruit and vegetables a day,
  • eat at least two portions of fish (one oily) a week, and
  • do a minimum of 30 minutes of moderate exercise, such as walking, cycling or energetic housework, at least five days a week.


  • Arteries: Arteries are blood vessels that carry blood from the heart to the rest of the body.
  • Very overweight: Obesity is when a person has an abnormally high amount of body fat.
  • Veins: Veins are blood vessels that carry blood from the rest of the body back to the heart.
  • Heart attacks: A heart attack happens when there is a blockage in one of the arteries in the heart.
  • Blood: Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.
  • Doses: Dose is a measured quantity of a medicine to be taken at any one time, such as a specified amount of medication.
  • Brain: The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.
Medical Review: October 04, 2008

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