Symptoms after thrombosis (post-thrombotic syndrome)

At a glance

  • Post-thrombotic syndrome can develop after deep vein thrombosis.
  • It happens if the leg veins have been damaged and blood can no longer flow properly.
  • The leg swells up and is painful. Over time, the skin around the lower leg might change color and start to itch.
  • Exercise, calf muscle training, elevating your legs, skin care and compression therapy can relieve the symptoms.
  • Plant-based medicines for treating veins have no proven effect, and are not recommended.


Photo of a woman with her hands on her leg

Some people develop what is known as post-thrombotic syndrome (PTS) a few weeks or months after having deep vein thrombosis. It can cause the affected leg to swell up and hurt. Itchy rashes on the skin and sometimes ulcers can form as PTS progresses.

The symptoms can restrict daily activities and are then very distressing. Itchy skin can cause insomnia, tiredness and drowsiness. Some people also find the visible changes to their skin very unpleasant.

There are various things you can do yourself to relieve the symptoms. Treatments such as medical compression stockings might also be an option depending on how severe the PTS is.

Post-thrombotic syndrome can also develop after thrombosis in the arm veins. But arm vein thrombosis is very rare.


There is a lot of variation in how many symptoms PTS causes, and how severe the symptoms are. The typical symptoms include:

  • Fluid retention (edema) in the ankle or lower leg
  • Sensation of heaviness and pain in the leg, especially the lower leg
  • Rashes and skin discoloration

The pain and swelling often get worse after standing or sitting for a long time. The swelling can make the skin on the lower leg feel tight. Other possible symptoms include tingling, itching, numbness, muscle cramps, and varicose veins.

Rashes and skin discoloration can develop over time: The skin can become inflamed and red. The skin can become dry and flaky, or leak fluid ("weep") and form a scab. Sensitive, brownish-reddish patches of harder skin can sometimes later develop. Scars may also form that later become lighter colored.


Post-thrombotic syndrome occurs if DVT has damaged the walls or valves of a vein, causing the blood to constantly build up in the vein. That causes a major pressure increase in the veins. The veins expand and the vein valves can no longer close properly.

Immune reactions can also damage the veins and contribute to PTS. This happens because immune cells and substances are released in the veins during DVT that can attack the walls and valves of the veins. That can lead to post-thrombotic syndrome after DVT.

The blood builds up in the affected veins if the vein valves leak. Because all veins are connected to each other, the surrounding veins are also put under pressure. Over time, fluid from the smallest vessels (the capillaries) can be pressed into the tissue where it builds up. That can stop the tissue from being supplied with oxygen-rich blood. The skin then no longer heals as well after injuries, and sometimes open sores and ulcers can develop.

Image: Back flow in a healthy vein and in a damaged vein

Risk factors

The risk of post-thrombotic syndrome is increased

  • following thrombosis in the hollow of the knee, the thigh, and especially in the pelvis,
  • with recurring thrombosis, and
  • if the thrombosis was not properly treated with medications to stop the blood from clotting.

Other risk factors include

  • Being very overweight
  • Smoking
  • Other vein conditions such as varicose veins
  • Older age

Prevalence and outlook

It is not entirely clear how many people develop post-thrombotic syndrome after DVT. In studies, 20 to 50 out of 100 people developed PTS.

The first symptoms often only develop several weeks or months after the DVT, sometimes even after one or two years.

It is not possible to predict exactly whether someone will develop PTS after a thrombosis and how severe it will be. Severe cases are quite rare: Open sores on the lower leg develop in about 5 out of 100 people.


Ulcers are a possible result of the high pressure in the veins. They usually form on the inner ankle or the shinbone and often weep. Small injuries sometimes turn into sores that get bigger over time and don’t heal well. These open sores can become chronic. They are then referred to as “venous ulcers.” Open sores can also become infected if bacteria get in there.


It is not possible to tell apart the symptoms of thrombosis and post-thrombotic syndrome at first. But if typical PTS symptoms develop three months after DVT, a PTS is very likely. Doctors usually spot it because of the typical symptoms. More involved examinations usually aren't needed to make a .

Special ultrasound examinations (Doppler or duplex ultrasound) can make the blood vessels and the blood flow in the vessels visible. That helps doctors to see whether the vein valves have been damaged and if the thrombosis has cleared up.

Ultrasound examinations of blood vessels are mainly done by specialists for internal medicine and dermatology or by surgeons. They have special qualifications in angiology, phlebology, or vascular surgery.

In special cases, other imaging techniques such as MRI () can also make sense, like if doctors suspect pelvic vein thrombosis.


DVT is generally treated with anti-clotting medications (“blood thinners”) for 3 to 6 months. Doctors sometimes recommend taking them for longer if there are certain risk factors.

Anti-clotting medications not only help to treat the acute thrombosis. They also lower the risk of another thrombosis. That means they can also prevent post-thrombotic syndrome. The risk of thrombosis recurring is higher in the first few months after a thrombosis.

Oral anticoagulants are the most commonly used medications. They are anti-clotting medications taken as tablets. The blood’s clotting ability has to be checked regularly and well adjusted when some of these medications are taken. That is the case for vitamin K antagonists such as “Marcumar” and “Falithrom.”

It is sometimes recommended that people wear medical compression stockings for up to two years after DVT to prevent PTS. Experts do not agree whether that helps. Studies have found inconsistent results.


There are different ways to relieve the symptoms of PTS:

  • Exercise: The calf muscles put pressure and tension on the veins when moving. That helps to pump blood out of the leg. Nordic walking, hiking, cycling and special calf muscle exercises are well suited.
  • Avoiding standing for long periods whenever possible: Blood builds up in the legs when standing, which can make the symptoms worse. It is a good idea to walk around a little and tap your feet from to time if you have to stand for a long time.
  • When sitting: Do not cross your legs because that can block the blood flow. Put your feet up from time to time if possible to help the blood flow out of the veins.
  • Skin care: Good skin care with moisturizing and lipid-replenishing creams and lotions can soothe itching and feelings of tight skin. It can also stop the skin drying out. Wound care therapists can give you specialist advice about which products might help you.
  • Avoidance of risk factors: Losing weight in the event of severe obesity, stopping smoking.
  • Compression therapy: Compression therapy improves blood flow by putting pressure on the leg veins. This can be done with compression bandages or by wearing medical compression stockings. More rarely, compression machines are used which put pressure on the leg by inflating alternating cushions of air.

There are no reliable studies into how effective these treatments are, though. But that doesn’t mean that they don’t work. It is just not yet possible to say whether, when and how well they help with post-thrombotic syndrome.

Several herbal products are also offered to treat PTS. But they are not recommended for treating post-thrombotic syndrome. There is no proof of their effectiveness and there is no reliable research into their side effects.

Other treatments might be an option to treat severe symptoms or certain complications:

  • Sometimes a vein in the pelvis is severely constricted or blocked. This is referred to as Iliac vein compression syndrome (IVCS) or May-Thurner syndrome. A stent can then be placed via a to improve blood flow.
  • If varicose veins are making the symptoms of post-thrombotic syndrome worse, they can be removed or closed using .

Leaking vein valves can also be operated on. But overall, surgery is only needed in rare cases to treat post-thrombotic syndrome. The advantages and disadvantages of different surgical techniques are not well studied, either.

Severe post-thrombotic syndrome with ulcers can be difficult to treat. Then it's a good idea to consult experts for internal medicine, dermatology, vascular medicine, and wound care. Specialist vascular clinics offer this kind of comprehensive care in Germany.

Further information

When people are ill or need medical advice, they usually go to see their family doctor first. Read about how to find the right doctor, how to prepare for the appointment and what to remember.

Appelen D, van Loo E, Prins MH et al. Compression therapy for prevention of post-thrombotic syndrome. Cochrane Database Syst Rev 2017; (9): CD004174.

Azirar S, Appelen D, Prins MH et al. Compression therapy for treating post-thrombotic syndrome. Cochrane Database Syst Rev 2019; (9): CD004177.

Deutsche Gesellschaft für Angiologie (DGA). Diagnostik und Therapie der Venenthrombose und der Lungenembolie (S2k-Leitlinie). AWMF-Registernr.: 065-002. 2015.

Kahn SR, Comerota AJ, Cushman M et al. The postthrombotic syndrome: evidence-based prevention, diagnosis, and treatment strategies: a scientific statement from the American Heart Association. Circulation 2014; 130(18): 1636-1661.

Makedonov I, Kahn SR, Galanaud JP. Prevention and Management of the Post-Thrombotic Syndrome. J Clin Med 2020; 9(4): 923.

Morling JR, Broderick C, Yeoh SE et al. Rutosides for treatment of post-thrombotic syndrome. Cochrane Database Syst Rev 2018; (11): CD005625.

Schleimer K, Barbati ME, Grommes J et al. Update on diagnosis and treatment strategies in patients with post-thrombotic syndrome due to chronic venous obstruction and role of endovenous recanalization. J Vasc Surg Venous Lymphat Disord 2019; 7(4): 592-600.

Wienert V, Flessenkämper I. Das postthrombotische Syndrom. VasoMed 2017; (6): 290-296.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Created on June 2, 2022

Next planned update: 2025


Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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