Prevention of Blood Clots During Chemotherapy

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Blood clots related to chemotherapy are talked about less than, say, nausea and vomiting, but that doesn't mean they are less of a problem. In fact, compared to the well-known symptoms of nausea, fatigue, and hair loss, they can be much more dangerous. That said, understanding the risk factors, knowing ways to lower your risk, and recognizing the symptoms can all help you reduce your risk during cancer treatment.

Ambulatory chemotherapy
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Blood clots—otherwise known in medical lingo as "venous thrombosis,” are indeed a significant concern in people with cancer. We've known for some time that people with cancer in general, not just those receiving chemotherapy, have an increased risk of blood clots.

On their own, blood clots in the arms and legs can be painful, but the greatest concern is that these clots will break off and travel to the lungs. When this occurs, something referred to as a pulmonary embolism, it is a medical emergency.

If you travel internationally, you may be familiar with the pre-flight videos which tout the importance of leg exercises to prevent blood clots, but we seldom hear of this risk with otherwise predisposing activities—such as going through chemotherapy.

In this case, what you haven't heard may hurt you. In fact, this is one aspect through which being your own advocate in your cancer care, learning about this potential complication, and contacting your healthcare provider if you are concerned—can really make a difference in your well-being and possibly even your outcome.

Risk Factors

It's always been suspected that people going through chemotherapy have an increased risk of blood clots, but it wasn't until 2013 that this aspect of cancer treatment was evaluated alone. In a large study, it was found that the incidence of blood clots going to chemotherapy was 12.6%, compared to a risk of 1.4% for cancer patients not receiving chemotherapy.

The risk was higher in some cancers than others, with cancers such as pancreatic cancer and lung cancer having greater risk. In addition, some chemotherapy drugs and medications used to counteract the side effects of chemotherapy were also associated with an increased risk. In this study, drugs which increased risk included Platinol (cisplatin), Avastin (bevacizumab), and Epogen or Procrit (the red blood stimulator erythropoietin.)


Common Causes & Risk Factors for Blood Clots

In addition to chemotherapy, what other treatments and conditions may raise the risk of blood clots for people living with cancer? Some risk factors include:

  • Surgery
  • Hospitalization, especially stays exceeding one day
  • Prolonged bed rest
  • Central venous access (such as having a chemotherapy port)
  • Medications called angiogenesis inhibitors (such as Avastin)


In order to be aware of possible symptoms, it can help to break these down into symptoms usually seen with a blood clot in the legs (venous thrombosis) and symptoms related to a blood clot that has broken off and traveled to the lungs (pulmonary embolism.)

Symptoms of venous thrombosis (blood clots in the leg) include symptoms in the calves or upper leg including:

  • Redness
  • Tenderness
  • Swelling
  • Warmth

Symptoms due to pulmonary embolism may include:

  • Sudden chest pain, often a sharp pain. Keep in mind that sometimes clots travel to different areas of the lungs, and pain may not be in just one location
  • Shortness of breath
  • Coughing or coughing up blood
  • Lightheadedness
  • Unconsciousness
  • Cyanosis, a blue discoloration of the skin and lips
  • Heart arrhythmias, abnormal heart rhythms
  • Elevated respiratory rate and heart rate with a low blood pressure


Medication: Medications such as anticoagulants are being used more frequently in recent years to reduce the risk of blood clots in cancer patients. This is referred to as a "prophylactic anticoagulation" which, translated, means preventative formation of a clot.

There are several medications healthcare providers may recommend prophylactically. Recent studies suggest that medications such as heparin work better in people with cancer than medications that interfere with vitamin K—such as Coumadin (warfarin), but different medications may be recommended depending on your particular situation. Some of these drugs (which you may hear referred to as low molecular weight heparin) include:

  • Lovenox (enoxaparin)
  • Fragmin (dalteparin)
  • Innohep (tinzaparin)
  • Arixtra (fondaparinux); this is a newer "heparin-like" drug

Self-Care: In medicine, we tend to talk about drugs when it comes to prevention, yet there are many things you can do yourself to reduce your risk. The first and most important step is simply to educate yourself and ask questions. Become familiar with the symptoms of blood clots and pulmonary embolism. If you are concerned at all, don't wait, but contact your healthcare provider immediately. Ask your oncologist if there is anything special you can do to reduce your risk, or if she would recommend a medication to lower risk. In addition, you may wish to:

  • Move around as much as possible, within your limits. If you are not sure how much activity is recommended, ask your healthcare provider. Frequent short periods of physical activity are better than infrequent longer activities. 
  • Even if you are bed-ridden, exercise your legs. Your healthcare provider or nurse can help demonstrate these exercises for you. You can try pointing your toes toward your head and then the floor several times (again, talk to your healthcare provider as the best measures may vary depending on your particular medical situation).
  • Avoid long drives. If you must be in the car for an extended period of time, schedule frequent stops, at least every hour, and get out of the car and walk around.
  • In addition to other precautions for flying with cancer, try to get up at least every hour, and preferably every 30 minutes and move around. You can do leg exercises even when seated. Depending on your situation, your oncologist may consider treating you with an anticoagulant (for example, low molecular weight heparin) prior to your flight. Make sure to ask. DVT's due to plane travel are common enough that they've been coined "economy class syndrome."
  • Don't smoke
  • If your healthcare provider recommends compression stockings, make sure to follow her directions
  • Avoid crossing your legs
  • Avoid tight-fitting clothing, especially clothing that is tight around your knees or in your groin area
  • Elevate your legs when possible
  • Avoid caffeine and alcohol. Both caffeine and alcohol can lead to dehydration, and dehydration raises the risk of blood clots.

Blood Clots Doctor Discussion Guide

Get our printable guide for your next healthcare provider's appointment to help you ask the right questions.

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6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Society of Clinical Oncology. Clotting problems.

  2. Khorana A, Dalal M, Lin J, Connolly G. Incidence and predictors of venous thromboembolism (VTE) among ambulatory high-risk cancer patients undergoing chemotherapy in the United States. Cancer. 2013;119(3):648-55. doi:10.1002/cncr.27772

  3. National Heart, Lung, and Blood Institute. Venous thromboembolism.

  4. Garcia Escobar I, Antonio Rebollo M, Garcia Adrian S, et al. Safety and efficacy of primary thromboprophylaxis in cancer patients. Clinical and Translational Oncology. 2017;19(1):1-11. doi:10.1007/s12094-016-1500-6

  5. Centers for Disease Control and Prevention. What is venous thromboembolism?

  6. Texas Heart Institute. Venous blood clots (including DVT).

Additional Reading

By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."