Conditions That Can Look Like UC

Medically Reviewed by Minesh Khatri, MD on April 09, 2023
3 min read

Ulcerative colitis (UC) is an inflammatory bowel disease that causes sores called ulcers to form in the lining of your colon or rectum. Its most common symptom is urgent and frequent diarrhea, which may be bloody or slimy, along with painful cramps in your belly or rectum.

Here are common conditions that can look like ulcerative colitis but aren’t.

Crohn’s is the most common disease to mimic ulcerative colitis symptoms. They are the two main types of inflammatory bowel disease (IBD). UC and Crohn's share some similarities, but their key differences include the location and degree of inflammation, as well as some symptoms that are more common or unique to each one.

Whereas UC happens only in your colon and rectum, Crohn’s can affect the entire digestive tract from mouth to anus. Also, the inflammation in your intestine tends to be more patchy in Crohn’s, with a mix of healthy and inflamed areas, while UC causes consistent and continuous inflammation along your entire colon.

Crohn’s has some symptoms that UC doesn’t, such as mouth sores, anal tears, fistulas, and narrowing of your intestine. Also, people who have UC might get blood in their stools or rectum more often than those with Crohn’s. Around 10% of IBD symptoms look like both UC and Crohn’s, but aren’t either one. In these cases, the doctor may diagnose it as “indeterminate colitis.”

IBS and IBD aren’t the same. They’re two distinct types of gut conditions that are diagnosed and treated differently. They are both chronic conditions that often start in young people. Scientists don’t know the exact cause of either one. IBS and ulcerative colitis share common symptoms such as diarrhea and belly pain. But UC is an autoimmune condition that involves inflammation, while IBS is not. It’s possible to have both IBS and an IBD like UC. IBS does not cause blood in the stool or increase your risk for other complications like colon cancer, while UC does.

Colon infections can be caused by bacteria, viruses, or parasites. These can inflame your gut lining and cause similar symptoms such as bloody diarrhea, abdominal pain, weight loss, and fever.

Often called “infectious colitis,” colon infections are usually one of the first things your doctor will try to rule out in a colonoscopy. They might test for bacteria in your stool or study other kinds of tissue in your intestines with a biopsy. Another sign that you might have UC instead of an infection is if your symptoms don’t get any better with treatment for infection.

The word “colitis” in ulcerative colitis can refer to any kind of inflammation in the lining of your large intestine or colon. There are a number of other things that inflame the lining of your colon without causing ulcers to form like in UC. This includes radiation, surgery, and diverticular colitis.

Microscopic colitis is inflammation that is too small to see with the naked eye and is diagnosed through a biopsy. It could also be related to a problem with your immune system but may be caused by bacteria, toxins, viruses, or even smoking. 

You can get diarrhea and bleeding from certain medications. The most common ones that bother your bowels are over-the-counter painkillers like nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen.