Patient information from BMJ

Deep vein thrombosis

Last published:Aug 05, 2021

If you have deep vein thrombosis (DVT) it means a blood clot has formed in a blood vessel. DVT can be dangerous if parts of the clot break off and travel to your lungs. But there are treatments that can help prevent this. You can also do things to reduce your chance of getting DVT again.

You can use our information to talk to your doctor about what treatments are best for you.

What is deep vein thrombosis?

Veins are the blood vessels that carry blood back to your heart from all the parts of your body. If a blood clot blocks a vein deep inside your body it's called deep vein thrombosis. It happens most often in the veins in your legs.

Blood clots can happen below or above your knee. A clot above your knee is more serious.

What are the symptoms?

DVT can cause swelling and pain in the calf or thigh of one leg. The affected part of your leg may also feel hot and turn red or purple. But most people who get DVT don't notice any symptoms.

If part of the blood clot breaks free it can travel through your blood vessels and get stuck in your lungs. This is called a pulmonary embolism and it can be very dangerous.

Symptoms of a pulmonary embolism include:

• breathlessness

• chest pain

• coughing up blood, and

• a racing heartbeat

It's also possible to have a pulmonary embolism without any of these symptoms, but this doesn't mean that it's not dangerous. Pulmonary embolism is more likely with a DVT above the knee.

It’s very important to see your doctor if you think you might have a blood clot. You may need tests, such as an ultrasound, x-ray, or lung scan. DVT may be caused by another medical condition, so your doctor may suggest tests to find out what caused your DVT.

What treatments are available?

The main treatment for DVT is medicines that help treat blood clots by thinning the blood. Your doctor might also advise you to wear special elastic stockings to help with any pain or swelling caused by DVT.

Drugs treatments for deep vein thrombosis

The main treatments for DVT are medicines called anticoagulants. These drugs:

• help prevent and break up blood clots

• reduce the chance of pulmonary embolism, and

• reduce the chance of DVT recurring.

There are many different anticoagulant drugs. So your doctor may have a choice of drugs that he or she can recommend, depending on what might suit you best.

Some anticoagulants need to be given in hospital, either as injections or as an intravenous (IV) drip. Or you might have your first treatment in hospital and then be taught how to give yourself injections at home.

A typical course of treatment might be:

• an injection or IV treatment in hospital, followed by

• injections of anticoagulants for five to seven days, either at home or in hospital, and

• a course of anticoagulant tablets. You are likely to need to take them for at least three months.

You might also need to have treatment in hospital if:

• you have severe symptoms: for example, if you have pain as well as swelling in your leg that shows up on an ultrasound scan

• you are not able to give yourself injections

• you have another medical condition that means you need to be monitored while you have anticoagulant treatment: for example, if you've recently had a stroke, or if you have liver disease.

Because anticoagulants help prevent your blood clotting they can sometimes cause unwanted bleeding. For example, you might bruise more easily, or have a nosebleed, or notice blood in your urine or stools (poo).

If you have unusual bleeding you should tell your doctor straight away. Your doctor may stop your treatment or give you other medicines to stop the bleeding.

If you take a course of pills of an anticoagulant called warfarin, your doctor should advise you about some things to bear in mind.

For example, the effect of warfarin on your blood can be affected by any other medicines you're taking, and by some foods, and by the amount of alcohol you drink. You’ll also need regular blood tests to check that you’re taking the right dose of warfarin.

Warfarin used to be commonly used for DVT. But it has mostly been replaced by newer drugs.

Pregnant women should not take warfarin. If you're pregnant and have DVT you'll probably be treated with an anticoagulant drug called heparin. If you are planning to breastfeed your baby there is a type of heparin that is safe to use while breastfeeding.

Elastic compression stockings

Following DVT, some people get swelling, sores on their skin, or damage to the tissue around the blocked vein. This is called post-phlebitic syndrome. Wearing special compression stockings may help prevent these problems.

You wear them during the day but you can take them off while you sleep, because you don't need them when you're lying down. You can buy them at a pharmacy. It's important to get them properly fitted to suit the size of your legs.

Exercise

Doctors recommend walking as a good type of exercise for people with DVT. Walking can help reduce DVT symptoms and problems caused by post-phlebitic syndrome.

Deep vein thrombosis and travel

Some research has found that long-distance travel, especially air travel, increases your chance of DVT. If you think you might be at risk, talk to your doctor. You might need to take medicines or wear compression stockings when you travel.

Some doctors advise not drinking a lot of alcohol and not taking sleeping tablets during long journeys. They also say you should try to exercise your legs by stretching them as you sit or by walking around as much as you can.

What to expect in the future

What will happen depends partly on where the DVT happens in your body. Blood clots in the veins in your thigh are more dangerous than clots below your knee. If you have DVT below your knee you may need more tests after about one week to make sure the DVT hasn't travelled above your knee.

DVT can come back in some people. If this happens to you, you will need more treatment.