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Deep vein thrombosis (DVT) - Treating deep vein thrombosis (DVT)

If you have deep vein thrombosis (DVT), you will need to take a medicine called an anticoagulant.


Anticoagulant medicines prevent blood clots getting bigger. They can also help stop part of the blood clot breaking off and becoming lodged in another part of your bloodstream (an embolism).

Although they are often referred to as "blood-thinning" medicines, anticoagulants do not actually thin the blood. They alter chemicals within it, which prevents clots forming so easily.

Two different types of anticoagulants are used to treat DVT:

  • heparin
  • warfarin

Heparin is usually prescribed first because it works immediately to prevent further clotting. After this initial treatment, you may also need to take warfarin to prevent another blood clot forming.


Heparin is available in two different forms:

  • standard (unfractioned) heparin
  • low molecular weight heparin (LMWH)

Standard (unfractioned) heparin can be given as:

  • an intravenous injection – an injection straight into one of your veins
  • an intravenous infusion – when a continuous drip of heparin is fed through a narrow tube into a vein in your arm (this must be done in hospital)
  • a subcutaneous injection – an injection under your skin

LMWH is usually given as a subcutaneous injection.

A dose of standard heparin can work differently from person to person, so the dosage must be carefully monitored and adjusted where necessary. You may need to stay in hospital for 5 to 10 days and have frequent blood tests to ensure you receive the right dose.

LMWH works differently from standard heparin. It contains small molecules, which means its effects are more reliable and you will not have to stay in hospital and be monitored.

Both standard and LMWH can cause side effects, including:

  • a skin rash and other allergic reactions
  • bleeding 
  • weakening of the bones (if taken for a long time)

In rare cases, heparin can also cause an extreme reaction that makes existing blood clots worse and causes new clots to develop. This reaction, and weakening of your bones, is less likely to occur when taking LMWH.

In most cases, you will be given LMWH because it is easier to use and causes fewer side effects.

Read more about heparin.


Warfarin is taken as a tablet. You may need to take it after an initial heparin treatment to prevent further blood clots occurring. Your doctor may recommend that you take warfarin for three to six months. In some cases, warfarin may need to be taken for longer, even for life.

As with standard heparin, the effects of warfarin vary from person to person. You will need to be closely monitored with frequent blood tests to ensure you are taking the right dosage.

When you first start taking warfarin, you may need to have two to three blood tests a week until your regular dose is decided. After this, you should only need to have a blood test every four weeks at an anticoagulant outpatient clinic.

Warfarin can be affected by your diet, any other medicines that you are taking, and by how well your liver is working.

If you are taking warfarin, you should:

  • keep your diet consistent
  • limit the amount of alcohol you drink (no more than three to four units a day for men and two to three units a day for women)
  • take your dose of warfarin at the same time every day
  • not start to take any other medicine without checking with your GP, pharmacist or anticoagulant specialist
  • not take herbal medicines

Warfarin is not recommended for pregnant women, who are given heparin injections for the full length of treatment.

Read more about warfarin.


The National Institute for Health and Care Excellence (NICE) recommends rivarixoban as a possible treatment for adults with DVT, or to help prevent DVT.

Rivarixoban prevents blood clots forming in blood vessels by stopping a substance called Factor Xa from working.

Treatment usually lasts for three months and involves taking rivarixoban twice daily for the first 21 days, followed by once daily until the course ends.

Read the NICE guidance on rivarixoban for the treatment and prevention of deep vein thrombosis.

Compression stockings

Compression stockings help prevent calf pain and swelling, and lower the risk of ulcers developing after having a DVT. They can also help prevent post-thrombotic syndrome. This is damage to calf tissue caused by the increase in venous pressure that occurs when a vein is blocked (by a clot) and blood is diverted to the outer veins. See complications of DVT for more information.

After having a DVT, stockings should be worn every day for at least two years because symptoms of post-thrombotic syndrome may develop several months or even years after having DVT.

Compression stockings should be fitted professionally and the prescription is reviewed every three to six months. They need to be worn all day, but can be taken off before going to bed or in the evening while you rest with your leg raised. A spare pair of compression stockings should also be provided.


Your healthcare team will usually advise you to engage in regular walking exercise once compression socks have been prescribed.

This can help prevent symptoms of DVT returning and may help to improve or prevent complications of DVT, such as post-thrombotic syndrome.

Raising your leg

As well as wearing compression stockings, you might be advised to raise your leg whenever you are resting. This helps to relieve the pressure in the veins of the calf and stops blood and fluid pooling in the calf itself.

When raising your leg, make sure that your foot is higher than your hip. This will help the returning blood flow from your calf. Putting a cushion underneath your leg while you are lying down should help raise your leg above the level of your hip.

You can also slightly raise the end of your bed to ensure that your foot and calf are slightly higher than your hip.

Read more information about preventing DVT.

Inferior vena cava filters

Although anticoagulant medicines and compression stockings are usually the only treatments needed, inferior vena cava (IVC) filters may be used as an alternative. Usually, this is because anticoagulant treatment needs to be stopped or is not suitable.

IVC filters are small mesh devices that doctors can place in a vein. They trap large fragments of a blood clot and stop it travelling to the heart and lungs.

They may be used to help prevent blood clots developing in the legs of people diagnosed with:

  • deep vein thrombosis (DVT)
  • pulmonary embolism
  • multiple severe injuries

They can be placed in the vein permanently, or newer types of filters can be removed once the risk of a blood clot has decreased.

The procedure to insert an IVC filter is performed using local anaesthetic (where you are awake but the area is numb). A small cut is made in the skin and a catheter (a thin, flexible tube) is inserted into a vein in the neck or groin area. The catheter is guided using an ultrasound scan. The IVC filter is then placed through the catheter into the vein.


An ulcer is a sore break in the skin, or on the inside lining of the body.
Pain is an unpleasant physical or emotional feeling that your body produces as a warning sign that it has been damaged.
Veins are blood vessels that carry blood from the rest of the body back to the heart.
Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.
Dose is a measured quantity of a medicine to be taken at any one time, such as a specified amount of medication.
Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.  
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Anticoagulant is a substance that stops blood from clotting (prevents coagulation). For example warfarin.
An embolism is the sudden blockage of a blood vessel, usually by a blood clot or air bubble.
Lungs are a pair of organs in the chest that control breathing. They remove carbon dioxide from the blood and replace it with oxygen.

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