The terms “IBS” and “IBD” are often used interchangeably to describe gastrointestinal discomfort, but they’re far from the same. “There are similarities in the presentation of IBS and IBD, but they are distinctively different conditions,” says Anthony Lembo, MD, a gastroenterologist and the Director of Research for Cleveland Clinic’s Digestive Disease Institute.

Short for irritable bowel syndrome, IBS is a chronic condition that can cause a variety of uncomfortable GI symptoms ranging from cramps and abdominal pain to diarrhea and constipation. There are three main types of IBS: IBS-C (constipation), IBS-D (diarrhea), and IBS-M (a mix of symptoms), which correspond to your bowel symptoms during a flare-up. Certain foods or stress may bring on symptoms, according to the Mayo Clinic.

Inflammatory bowel disease, or IBD, is a term that encompasses both Crohn’s disease and ulcerative colitis, both of which involve inflammation in the tissues of the digestive tract (though ulcerative colitis is confined to the large intestine). Like IBS, IBD is a chronic condition, and some symptoms can be similar. But unlike IBS, the inflammation that occurs in the GI tract can cause long-term damage for people with IBD.

Read on for everything you need to know about both conditions, including how providers diagnose each as well as the treatment options.

What causes IBS and IBD?

There’s still a lot we don’t know about IBS and IBD, and “the exact causes of both [conditions] are largely unknown,” says Alyssa Maria Parian, MD, a gastroenterologist and Associate Professor of Medicine at Johns Hopkins Medicine. However, existing research can clue us in to some possible culprits:

Potential IBS causes

IBS is considered a neurogastrointestinal disorder, which means that a person’s gut and brain don’t work properly together to manage the digestive system. And while we don’t know exactly what causes this to happen, “there are factors that are thought to contribute,” says Samantha Nazareth, MD, a gastroenterologist practicing in New York City.  That includes abnormal gut muscle contractions, issues with the nerves in the digestive system, changes in the gut microbiome, or food intolerances. “IBS can also develop after a bad case of gastroenteritis [aka, the ‘stomach flu’],” Dr. Nazareth adds.

Potential IBD causes

With IBD, experts believe the cause is likely a combination of a malfunctioning immune system, the environment, and genetics. “It does run in families,” says Dr. Parian. “There is also believed to be a triggered event that isn’t clearly defined, but may be a viral infection or antibiotic use that disrupts the gut microbiome.”

“By definition, the diagnosis of IBS can be made only after ruling out other GI disorders, [including IBD,]” —Gail Hecht, MD, gastroenterologist

What are the signs and symptoms of IBS vs. IBD?

IBS symptoms

Everyone experiences GI distress from time to time. But with IBS, the symptoms may come and go but tend to last longer. They also tend to be triggered by something specific, such as certain foods or stress. You may notice:

• New or unusual bowel movement changes
• Sharp abdominal pain or cramping
• Bloating
• Constipation or diarrhea (or a mix of both)
• A feeling of fullness

IBD symptoms

If you have ulcerative colitis or Crohn’s disease, you may experience:

• Diarrhea
• Abdominal pain
• Cramps
• Gas
• Bloating
• Blood in your stool
• Fatigue
• Lower appetite
• Weight loss

How severe are IBS and IBD?

Both IBS and IBD can present on a spectrum, with symptoms ranging from more mild to more severe. With IBS, symptoms may be frequent or come and go; many people with the condition are still able to complete day-to-day activities, while others find it difficult to function during a flare.

People with IBD, too, may experience a milder form of the illness, but this condition can also be extremely debilitating. “While IBS doesn’t cause tissue damage, IBD can lead to serious complications,” says Dr. Parian. Unfortunately, that can include an increased risk of colon cancer, per the Crohn’s & Colitis Foundation. Surgery may be required for people with IBD when medication can no longer manage symptoms.

IBD may up your risk of having other chronic conditions as well. Data from the 2015 and 2016 National Health Interview Survey found that adults with IBD are more likely to have diabetes; heart, lung, or kidney disease; cancer; arthritis; and ulcers.

How common are IBS and IBD?

Of the two conditions, IBS is more common, affecting about 15 percent of people in the U.S., according to Johns Hopkins Medicine. (In fact, IBS is considered the most commonly diagnosed disease by gastroenterologists, the Cleveland Clinic notes.)

A smaller percentage of the population has IBD—around 1.3 percent, per the Centers for Disease Control and Prevention (CDC).

Diagnosis and treatment for IBS and IBD

IBS

No single test currently exists to determine whether a person has IBS. So instead, providers use a variety of procedures and tools to make a diagnosis, such as blood or stool tests, a colonoscopy, or upper endoscopy. Your doctor will also ask you about your symptoms to make sure you don’t have any other conditions.

“By definition, the diagnosis of IBS can be made only after ruling out other GI disorders,” says Gail Hecht, MD, a gastroenterologist, Wonderbelly Medical Advisor, and former American Gastroenterological Association president.

There isn’t a cure for IBS. But once your doctor determines you have this condition, they’ll help you come up with a plan to manage your symptoms. “IBS is typically treated with lifestyle modifications,” says Dr. Parian.

This can look a little different from person to person, but your practitioner will likely recommend drinking plenty of water, avoiding foods that trigger your symptoms (dairy, foods that contain gluten, and “gassy” foods like beans and cruciferous veggies are common culprits), and trying a low-FODMAP diet, which limits harder-to-digest fermentable short-chain carbohydrates.

Medication may also help relieve IBS symptoms, and there’s evidence to suggest that different types of therapies (including hypnotherapy, cognitive behavioral therapy, and biofeedback) can be beneficial, too.

IBD

As with IBS, there isn’t one test to diagnose IBD, but many of the same procedures (such as a colonoscopy, upper endoscopy, and stool tests) are used to look for intestinal inflammation and determine if you have Crohn’s disease or ulcerative colitis.

Both of these conditions are chronic, which means there’s no cure. But they can be managed with a combination of medication and lifestyle changes (avoiding trigger foods and managing your stress, for example) to reduce flares and minimize the inflammation you experience.

Some people with Crohn’s disease and ulcerative colitis eventually need surgery once they are no longer able to manage their symptoms with medication.

When to see a doctor

People experiencing GI symptoms don’t always feel empowered to get the treatment they need. According to a 2018 survey of more than 71,000 Americans, around 60 percent reported GI discomfort in the prior week, but older research suggests that fewer than 20 percent of people with these types of symptoms bring them up to a doctor. If you have any of the IBS or IBD symptoms above—particularly if they’re getting progressively worse or you have a family history of either condition—make an appointment with your provider. Both IBS and IBD can be improved with treatment, and the first step to feeling better is seeking care.

And there are other reasons to be in regular contact with your doctor about GI discomfort: IBS and IBD can sometimes mimic symptoms of colon cancer, which “we’re seeing present earlier and earlier,” says Dr. Parian. Schedule an appointment with your provider ASAP if you’re noticing any especially concerning symptoms, such as blood in your stool, anemia, unexplained weight loss, or a fever.

FAQ

Can IBS turn into IBD?

No, IBS can’t “turn into” IBD, experts say. “These diseases are separate disorders,” says Dr. Hecht. However, it is possible for someone to have IBD symptoms (think: abdominal discomfort, diarrhea, and cramping) before the condition is officially diagnosed. The two conditions can also go hand in hand: IBD patients are three times more likely to have a prior history of IBS, research has found.

Can you have IBS and IBD?

It’s certainly possible. While IBS doesn’t necessarily lead to IBD, it can be “very common” to have IBS and IBD together, says Dr. Parian. According to a 2012 systematic review and meta-analysis, 35 to 40 percent of people who had confirmed IBD also reported symptoms of IBS (this is the most comprehensive research done in this area to date). What’s more, patients with active IBD were nearly five times more likely to have IBS-compatible symptoms compared to those in the control group.

How often is IBD misdiagnosed as IBS?

Because there’s no specific test for IBS, providers use a number of procedures ranging from colonoscopies to CT scans to an upper endoscopy to rule out various other conditions. “Typically, [IBS] is a diagnosis of exclusion,” says Dr. Hecht. As a result, some research suggests around 10 percent of patients who actually have IBD are misdiagnosed with IBS at first.

—reviewed by Jennifer Gilbert, MD, MPH