What Causes Ulcerative Colitis?

Ulcerative colitis happens when your body’s immune system doesn’t work properly. It causes inflammation in the inner lining of your colon. The irritation and swelling in turn lead to ulcers and open sores in the lining.

Your immune system defends you from infections, illnesses, and things that don’t belong in your body. But in an autoimmune disease like ulcerative colitis, it mistakenly attacks your own body.

It sends in your white blood cells, which attack your intestinal lining. That leads to ongoing inflammation.

No one knows exactly what causes ulcerative colitis. But experts think that one of three things may trigger it.


You might have inherited a gene that causes ulcerative colitis. It could run in your family. Experts have found certain abnormal genes in some people who have it.

Immune System

An infection might have triggered your immune system, but then for some reason, it doesn’t turn off. That leads to the colon inflammation that causes symptoms of ulcerative colitis.


A germ, like a virus in your environment, might raise your chances of getting ulcerative colitis.

If you use nonsteroidal anti-inflammatory drugs, antibiotics, or birth control pills, your chances of having it may increase slightly. It’s possible a high-fat diet is related to it, too.

A few other things could be related to the cause or might trigger a flare-up:

  • Stress
  • Emotional distress
  • Some kinds of food


Who’s at Risk?

Anyone can get ulcerative colitis. But if you’re an older man, you’re more likely to get it than an older woman. And even though it can strike at any age, it usually begins before you’re 30 or after 60.

If someone in your family has ulcerative colitis, you’re more likely to get it, too. But only 20% of people with the disease also have a close relative with it.

If you’re white and of European descent or if you’re Jewish, you’re also more likely to get the condition.

Is This My Fault?

No. Scientists don’t really know why your immune system starts to go haywire and inflames your bowel in ulcerative colitis. What seems fairly clear, though, is that it has little to do with what you’ve done in the past. You didn’t catch UC from some infected person or from eating or drinking the wrong thing. Nor did you get it from simply being stressed out.

That said, both hard-to-digest foods and stressful situations can trigger or worsen a flare-up of UC symptoms, if you already have the disease. You can often improve your symptoms if you avoid certain high-fiber foods like uncooked veggies, nuts and seeds, as well as fatty or greasy foods like burgers and fries. Use common sense. If you find that certain foods upset your stomach, try to stay away from them.

It can also help to maintain balanced mental health and avoid unnecessary stress and anxiety. Proper sleep, quitting smoking, and regular exercise could also keep flare-ups at bay.

WebMD Medical Reference Reviewed by Neha Pathak, MD on November 15, 2021



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