Ulcerative Colitis and Blood Clots: How to Lower Your Risk
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The Link Between Ulcerative Colitis and Blood Clots, and How to Protect Yourself

The inflammation from UC can also increase your risk of a blood clot. Follow these steps to protect yourself.
The Link Between Ulcerative Colitis and Blood Clots, and How to Protect Yourself
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By
and Tabitha Britt
Updated on October 16, 2025
by

Living with ulcerative colitis (UC) means managing symptoms like bloating and cramps, but there’s another serious complication to be aware of: a higher risk of blood clots.

In fact, research shows that people with inflammatory bowel disease (IBD), including UC and Crohn’s disease, are 2 to 3 times more likely to develop a potentially life-threatening clot than those without IBD.
These clots often form as deep vein thrombosis (DVT), which is a clot in a deep vein in the leg, pelvis, or arm. If a piece breaks off and travels to the lungs, it can cause a dangerous blockage called a pulmonary embolism.

Fortunately, there are steps you can take to lessen your odds of developing a blood clot. Here’s what to know about UC and blood clots and how to protect yourself.

Ulcerative Colitis and Blood Clots: What’s the Link?

The same inflammation that causes the digestive symptoms of UC is the primary reason for the increased risk of blood clots. “Ulcerative colitis is a condition where the immune system causes ongoing inflammation in the colon. This inflammation can affect the blood and make it more likely to clot,” says Maliha Naseer, MD, a gastroenterologist at the Cleveland Clinic in Cleveland, Ohio.

This inflammation disrupts your body’s natural systems for preventing clots in a few ways:

  • It changes your blood’s consistency. Inflammation can signal your body to produce more platelets and other clotting factors, while at the same time making less of the natural proteins that work to prevent clots.
  • It can damage the lining of your blood vessels. The inner surface of your veins can be harmed by chronic inflammation, creating a rough spot where a clot is more likely to form.
  • It can cause blood flow to slow down. “During flare-ups, symptoms like belly pain, diarrhea, and tiredness can lead to less movement. Staying still for long periods increases the risk of clots,” says Dr. Naseer. Dehydration from diarrhea can also contribute by making the blood thicker and slowing its flow, she says.
Genetics may also be a factor. Research has found that about 1 in 7 people with IBD carry specific genetic markers that increase their risk of a blood clot by 2.5 times, compared with people with IBD who do not have those markers.

How to Lower Your Risk of Blood Clots

The most important step in lowering your risk is to work closely with your healthcare team. You should discuss your personal risk for blood clots and create a plan for prevention, especially when your UC is flaring.

Keeping your UC in remission is also a part of prevention. Research shows that about three-quarters of blood clots in people with IBD occur when the disease is actively flaring.

However, the risk doesn’t disappear completely when symptoms subside. “Even when UC is under control, the risk of blood clots is higher than normal,” says Naseer. “Some inflammation, active platelets, and genetics can keep this risk elevated.”

Here are more steps you can take.

1. Know the Symptoms of DVT

It’s possible to have DVT without any warning signs or symptoms. Approximately 30 percent of people with DVT experience no symptoms at all.
However, you should contact your doctor right away if you experience one or more of the following symptoms:
  • Swelling in the legs or arms
  • Pain or tenderness not caused by an injury in these areas
  • Skin on the arm or leg that feels warm to the touch
  • Redness or discoloration of the skin on the arm or leg
You should call 911 or seek immediate medical attention if you suddenly experience any of these symptoms:

  • Sudden difficulty breathing
  • Chest pain that worsens when you take a deep breath
  • Coughing up blood
  • A fast or irregular heartbeat or breathing
  • Feeling lightheaded, dizzy, or fainting

2. Stay Active

“Because ulcerative colitis can make blood more likely to clot, staying active is very important,” says Naseer. “Try to walk several times a day, even for short distances. If you’re sitting or lying down for long periods, move your legs and flex your ankles.” This helps keep your blood circulating effectively.

3. Review Your Medications

Certain medications can increase the risk of blood clots as a side effect, so it’s important to review everything you take with your doctor. This includes treatments for both your UC and any other conditions you have. A few examples include:

  • Corticosteroids: “Steroids can help manage flares but may double or quadruple clot risk, which is why we use them only short-term and taper them quickly,” says Naseer.
  • JAK inhibitors: This class of medication is an effective treatment for UC but carries a possible risk of blood clots, which is noted in a warning from the U.S. Food and Drug Administration.
  • Combined hormonal birth control: Some forms of birth control, including the combination pill, patch, and ring, may slightly increase the risk of DVT.

This doesn’t mean you can’t take these medications — rather, this is something your doctor will take into consideration when determining the best treatment for you. Don’t stop taking your medications without talking to your doctor first. Treating your condition and achieving remission is the priority.

4. Quit Smoking

Quitting smoking is another important step in lowering your risk. Smoking damages the lining of your blood vessels and makes blood platelets more likely to stick together, both of which increase the chances of a clot forming.

5. Manage Your Weight

Maintaining good habits that support a healthy weight is important. Research suggests that being overweight or having obesity may be linked to more severe disease activity and can sometimes reduce the effectiveness of certain therapies.

6. Be Mindful When Traveling

Sitting for long periods can slow your circulation and increase the risk of a blood clot, especially during travel that lasts more than four hours.

“On long trips, stand up and stretch at least once every hour or two,” says Naseer. “Keeping your blood moving is one of the simplest and most effective ways to lower your risk of clots.”

If you can’t get up, you can do simple leg exercises in your seat to promote blood flow:
  • Raise your heels while keeping your toes on the floor, then lower them.
  • Next, raise your toes while keeping your heels on the floor, then lower them. Do this for 30 seconds and repeat as many times as you’d like.

7. Have a Plan Before and After Surgery

Being hospitalized for a severe UC flare or surgery increases your risk of developing a blood clot. Your healthcare team will take steps to protect you during this vulnerable time.

To prevent clots, it’s standard practice for hospitals to administer a low dose of blood-thinning medication via injection.

After surgery, you’ll be encouraged to get out of bed and start moving as soon as it’s safe to do so. This early movement is another strategy for preventing blood clots.

The Future of Preventing Blood Clots in Ulcerative Colitis

Researchers are actively developing new ways to reduce the risk of clots in people with UC by focusing on genetic risk factors, improving risk-assessment tools, and exploring the role of anti-inflammatory medications, says Naseer.

Some strategies target the immune system by focusing on specific cells and proteins that make blood clot, she says. “Drugs that calm overactive platelets and new blood thinners are also being studied,” says Naseer. “Hospitals are using smart approaches, like extending preventive blood thinners after surgery, to keep patients safe.”

The Takeaway

  • Having ulcerative colitis increases your risk of developing a serious blood clot. That’s mainly because the chronic inflammation from the disease can make your blood more prone to clotting.
  • Working closely with your doctor to keep your UC in remission is a key part of prevention, as most clots happen during flares.
  • You should also review all your medications and lifestyle risk factors for blood clots, such as smoking, with your healthcare team.
  • Learn the warning signs of a blood clot. Contact your doctor if you have symptoms such as swelling or pain in a leg or arm, and call 911 immediately if you experience signs of a pulmonary embolism, such as sudden shortness of breath.

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Waseem-Ahmed-bio

Waseem Ahmed, MD

Medical Reviewer

Waseem Ahmed, MD, is an assistant professor of medicine in the Karsh Division of Gastroenterology and Hepatology at Cedars-Sinai Medical Center in Los Angeles and serves as Director, Advanced Inflammatory Bowel Disease Fellowship and Education within the F. Widjaja Inflammatory Bowel Disease Institute.

He received his undergraduate degree from the University of Michigan and attended medical school at Indiana University. He then completed an internal medicine residency at New York University, followed by a fellowship in gastroenterology and hepatology at Indiana University, and an advanced fellowship in inflammatory bowel disease at the Jill Roberts Center for Inflammatory Bowel Disease at New York-Presbyterian Hospital/Weill Cornell Medicine. Prior to his current role, Dr. Ahmed served as an assistant professor of medicine within the Crohn’s and Colitis Center at the University of Colorado from 2021-2024.

Dr. Ahmed is passionate about providing innovative, comprehensive, and compassionate care for all patients with inflammatory bowel disease (IBD). His research interests include IBD medical education for patients, providers, and trainees; clinical trials; acute severe ulcerative colitis; and the use of combined advanced targeted therapy in high-risk IBD.

He enjoys spending time with his wife and dog, is an avid follower of professional tennis, and enjoys fine dining.

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Jessica Migala

Author

Jessica Migala is a freelance writer with over 15 years of experience, specializing in health, nutrition, fitness, and beauty. She has written extensively about vision care, diabetes, dermatology, gastrointestinal health, cardiovascular health, cancer, pregnancy, and gynecology. She was previously an assistant editor at Prevention where she wrote monthly science-based beauty news items and feature stories.

She has contributed to more than 40 print and digital publications, including Cosmopolitan, O:The Oprah Magazine, Real Simple, Woman’s Day, Women’s Health, Fitness, Family Circle, Health, Prevention, Self, VICE, and more. Migala lives in the Chicago suburbs with her husband, two young boys, rescue beagle, and 15 fish. When not reporting, she likes running, bike rides, and a glass of wine (in moderation, of course).

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Tabitha Britt

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Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
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