IBD vs. IBS

Medically Reviewed by Minesh Khatri, MD on June 19, 2022
Written by WebMD Editorial Contributors
4 min read

Inflammatory bowel disease (IBD) includes two conditions that cause swelling and irritation in your digestive tract; Crohn’s disease and ulcerative colitis. Irritable bowel syndrome (IBS) is a condition in which contents move too fast or too slow through the intestines, usually accompanied by abdominal pain.

IBD is what doctors call a structural disease. That means physical damage causes your symptoms. Doctors can see chronic inflammation or ulcers when they look at your gut with an X-ray, endoscopy, surgery, or biopsy. 

IBS is a functional disease. Tests won’t show any physical reason for your symptoms. 

You can’t tell which condition you have by how you feel. Here’s how to know the difference so you can get the right treatment.

 

Because IBD and IBS are both long-term conditions that affect your gut, they have some similar symptoms:

  • Belly pain
  • Bloating
  • Diarrhea or constipation
  • Pooping more often or feeling like you need to go right away

Both also tend to be diagnosed in young people.

The inflammation of IBD can cause symptoms that get worse over time, including:

  • Bloody or black stools
  • Weight loss or loss of appetite
  • Fever
  • Inflammation in your skin, joints, or eyes

IBS can cause nausea and more gas than usual. You may feel like you still need to go after a bowel movement.

Crohn’s disease, one of the main forms of IBD, usually causes pain in the lower right side of your belly. The other main form, ulcerative colitis, leads to pain in the left side of your belly. Both, however, can cause pain anywhere in the abdomen.

If you have IBS, you probably have pain or cramps in the lower half of your belly.

Physical signs have helped doctors learn what causes IBD.

The long-lasting inflammation in the digestive tracts of people who have IBD can cause bleeding and ulcers (sores). In turn, this irritation causes pain. That triggers the immune system, which leads to symptoms like fever and fatigue.

The causes of IBS aren’t as clear. Scientists have found links to the immune system and how muscles move food through your gut. Many people have triggers that make their symptoms worse, including certain foods, stress, infections, and hormonal changes.

Diagnosing IBD

Your doctor will look for physical damage in your intestines. You might have:

  • Tests of your blood and poop
  • CT or MRI scans
  • A colonoscopy to look inside your body. Your doctor may take a small tissue sample at the same time. This is called a biopsy.

If you have inflammation and ulcers, your doctor can use these tests to narrow down what form of IBD you have.

Diagnosing IBS

Doctors use the “Rome criteria” to look for irritable bowel syndrome. These say that you may have IBS if you have belly pain for at least 1 day a week for 3 months. The pain must also meet at least two of the following:

  • It happens with a bowel movement.
  • When it starts, you begin to have bowel movements more or less often.
  • Your poop looks different when it happens. 

In some cases, doctors will diagnose you with IBS just using these standards. But sometimes, especially if you also have other symptoms that hint at IBD, you’ll get tests to find out whether there’s any bleeding or inflammation in your digestive tract. If there is, you don’t have IBS.

Without treatment, IBD can lead to serious problems such as:

  • Dehydration
  • Poor nutrition
  • Anemia
  • Bone loss
  • Infection
  • Blood clots
  • Ulcers
  • Blocked bowels
  • Fistulas and abscesses
  • A hole in your colon
  • A rapid widening of your colon
  • A higher risk of colon cancer

IBS is less dangerous. Its main complication is usually how the symptoms affect your quality of life. It may also cause depression or anxiety.

People who have IBD or IBS often try to treat it by changing what they eat. There’s no specific diet that works for everyone. Ask your doctor if it would help to:

  • Get more fiber (from food or supplements).
  • Avoid lactose, which is in dairy products.
  • Cut down on foods that make you gassy or bloated.
  • Get more water. (You can drink it or eat water-rich foods.)
  • Avoid caffeine and legumes (beans).
  • Limit or avoid FODMAPs, a type of sugar found in some fruits, vegetables, breads, and dairy products.

Doctors usually treat IBD with drugs that target the inflammation:

  • Aminosalicylates work on the lining of your intestine. They help in mild or moderate cases of IBD.
  • Corticosteroids weaken your immune system. You’ll take them for a short time if your symptoms flare up.
  • Immunomodulators also affect your immune system. You can use them as a long-term treatment.
  • Biologic therapies keep proteins in your body from causing inflammation.
  • Antibiotics fight infection caused by the disease or from surgery to treat it.

These meds generally don’t work for IBS, which is one reason why it’s so important to know which condition you have.

Some people who have IBD need surgery to repair the damage to their digestive tract, but those with IBS don’t.

If you have IBS, your doctor may recommend over-the-counter or prescription drugs to help with diarrhea or constipation. These include laxatives or anti-diarrheals, antispasmodics, and antidepressants.

Other things that can help include stress management, acupuncture, hypnotherapy, and relaxation training. Researchers are also studying whether probiotics help ease IBS.

Counseling can be helpful, especially if your condition causes stress or if you notice that you're limiting your social life because you worry about your symptoms. A support group is another great resource because the people there will understand from experience what it’s like to have IBS. They can offer tips on how to manage it and improve your quality of life.