IBD vs IBS vs Colitis: What’s the Difference?

Digestive discomfort can have many causes, and conditions like IBD, IBS, and colitis often sound similar—but they aren’t the same. This guide breaks down what each means, how they differ, and when to talk to your doctor. 

Understanding the conditions 

Inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and colitis all affect the digestive system but in different ways. Knowing which condition you might have helps guide proper care and treatment. 

“Colitis is a general term for inflammation in the colon,” explains Heather Stewart, NP, gastroenterology provider at CoxHealth. “Inflammatory bowel disease includes both Crohn’s disease and ulcerative colitis. These are autoimmune conditions that cause chronic inflammation in the GI tract.” 

IBS, on the other hand, causes gastrointestinal symptoms without visible inflammation or disease. That means the intestines may appear healthy during testing, even though a person experiences pain or irregular bowel movements. 

Takeaway: Colitis involves inflammation. IBD is a chronic disease that causes inflammation. IBS does not cause inflammation but can mimic similar symptoms. 

How they’re related—and how they differ 

Colitis is a broad term that describes any inflammation in the colon. Ulcerative colitis and Crohn’s disease fall under the IBD category. IBS shares some symptoms but is not related to inflammation or autoimmune activity. 

“I would describe ulcerative colitis and Crohn’s disease as sister conditions,” says Heather Stewart, NP. “Ulcerative colitis affects only the colon and rectum, while Crohn’s disease can involve the colon, small intestine, or even upper GI areas.” 

IBS, the most common of the three, is a functional disorder—meaning the gut isn’t inflamed but reacts abnormally to stress, diet, or hormones. 

Key differences: 

• IBD: Autoimmune inflammation (includes Crohn’s disease and ulcerative colitis)
• IBS: Functional digestive disorder without inflammation
• Colitis: General inflammation in the colon, sometimes caused by infection or IBD 

Takeaway: IBS is more common and less severe, while IBD and chronic colitis require medical treatment to prevent complications. 

Symptoms and when to seek care 

While the symptoms can overlap, certain signs may point toward one condition over another. 

Common symptoms include: 

• Abdominal pain or cramping
• Bloating
• Diarrhea or constipation 

More concerning symptoms include: 

• Blood in stool or rectal bleeding
• Weight loss
• Persistent diarrhea lasting more than six weeks 

“True intestinal inflammation and IBS can cause very similar symptoms,” explains Heather Stewart, NP. “Often a colonoscopy is necessary to distinguish between the two.” 

If symptoms last for weeks or you notice blood in your stool, it’s time to talk to your primary care physician. They can help you decide whether to see a specialist or schedule testing. 

Takeaway: Long-lasting or worsening digestive symptoms should never be ignored—especially if you notice bleeding or weight loss. 

Diagnosis and testing 

Your provider may recommend one or more of the following tests to determine what’s causing your symptoms: 

• Colonoscopy: Allows your doctor to view the inside of your colon and detect inflammation or signs of IBD.
• Upper endoscopy: Checks the upper digestive tract if symptoms extend beyond the colon.
• Lab and stool tests: Including fecal calprotectin, which helps detect intestinal inflammation.
• Imaging tests: Sometimes used to look for inflammation or other abnormalities. 

“Colonoscopy is a very routine, low-risk procedure,” Heather Stewart, NP, notes. “It’s often the best way to tell the difference between IBD and IBS.” 

Takeaway: Testing helps doctors confirm the right diagnosis so treatment can begin early—before symptoms worsen or complications develop.