Why blood clots are more common in people with IBD

What is IBD?

The term “IBD” or “Inflammatory bowel disease” refers to two different conditions characterized by chronic inflammation of the GI (gastrointestinal tract):

  • Crohn’s disease;
  • Ulcerative colitis.

According to experts, patients with IBD are more likely to develop blood clots, which obstruct the blood flow traveling through arteries and veins, and causing damage to the organ they wind up at. Heart attacks and strokes are among the most common complications of blood clots.

It is not clear why blood clots are more likely to occur in people with IBD, but – at the same time – it is fundamental that patients do not underestimate the risk and focus on prevention.

Causes and risk factors for blood clots

There is a large number of conditions linked to a higher risk of developing blood clots, such as:

  • Atherosclerosis;
  • Atrial fibrillation;
  • Diabetes;
  • DVT (deep vein thrombosis);
  • Heart failure;
  • Metabolic syndrome;
  • Peripheral artery disease;
  • Vasculitis.

Risk factors for blood clots include:

  • Cancer;
  • Dehydration;
  • Genetics;
  • Hospitalization;
  • Injury to a vein;
  • Obesity and overweight;
  • Personal history of blood clots;
  • Personal history of miscarriages;
  • Recent accident (such as a car accident);
  • Sitting for long periods or being on bed rest;
  • Smoking;
  • Surgery;
  • Use of estrogen-based medications, such as birth control or hormone therapy.

Research on the link between blood clots and IBD

According to a Danish study (1980-2007   ), people with IBD have twice the risk of pulmonary embolism and DVT. Even considering all the other potential risk factors, such as preexisting diseases/conditions or the use of certain medication, the risk of having blood clots in the IBD group was 80% higher than the control groups.

Another British study (2010   ) investigated the risk of blood clots in people with IBD, comparing patients who were experiencing a flare-up and those who didn’t have the active disease. Both groups were shown to have a much higher risk compared to the control group. In the case of hospitalized IBD patients, the risk was eight times higher.

It is worth mentioning that the personal risk of having blood clots depends on many factors, such as:

  • Age;
  • Family history;
  • Activity level;
  • Medications;
  • Pregnancy.

According to the Guidelines from the Canadian Association of Gastroenterology published in 2014   , it is only recommended to use anticoagulant medications for patients with IBD after surgery or while hospitalized, and not to prevent blood clots on a daily basis.


In general, in order to prevent blood clots, it is recommended to:

  • Exercise;
  • Keep a healthy weight;
  • Drink enough water;
  • Manage related conditions (i.e. diabetes).

It is fundamental that people with IBD work with a physician to find the best medication to prevent blood clots. Anti-clotting medications might be prescribed, but only after surgery or while hospitalized.


It is important to take blood clot risk into account when dealing with IBD patients. If you suffer from IBD and have concerns about your personal risk, you should talk to your doctor and other specialists, such as a gastroenterologist.


Humanitas is a highly specialized Hospital, Research and Teaching Center. Built around centers for the prevention and treatment of cancer, cardiovascular, neurological and orthopedic disease – together with an Ophthalmic Center and a Fertility Center – Humanitas also operates a highly specialised Emergency Department.