IBS and IBD: How are they different and how are they treated?

Published Apr 3, 2021 • By Courtney Johnson

Though many people may use the terms IBS and IBD interchangeably, they are in fact two distinct conditions that require very different treatments.

What are IBS and IBD? How are they different? How are they diagnosed and treated?

We explain it all in our article!

IBS and IBD: How are they different and how are they treated?

When you’re experiencing chronic gastrointestinal issues, you may hear a number of acronyms in conversation with your doctor or medical, such as IBS and IBD. While their names are similar and they share similar symptoms, IBS and IBD are actually different conditions that require different treatments. 

It is important to have a good understanding of your condition so that you can grasp the implications of your gastrointestinal and ask your doctor the right questions.

Read on to learn more about the key differences between the two!

What is IBD? 

Inflammatory bowel disease (IBD) is an umbrella term used to describe a group of bowel diseases that are characterized by chronic swelling (inflammation) of the gastrointestinal (GI) tract. The most common forms of IBD are Crohn’s disease and ulcerative colitis.

IBD is a structural disease, meaning that the symptoms presented by the disease are caused by physical damage in the body. When a doctor examines the gut using X-ray, endoscopy, surgery or biopsy, for example, he or she is able to visually see ulcers or chronic inflammation.

In ulcerative colitis, the inflammation occurs in the large intestine, which is also called the colon. There are different classes of UC, depending on their location and severity. They include:

  • Universal colitis (pancolitis): When inflammation is spread across the entire colon.
  • Ulcerative proctitis: This is considered the mildest form of UC and occurs when inflammation stays within the rectum
  • Distal colitis: When inflammation extends from the rectum and up the left colon.
  • Proctosigmoiditis: When inflammation occurs in the rectum and lower end of the colon.
  • Acute severe ulcerative colitis: This is a rare type of UC causing inflammation across the entire colon and leading to severe pain and symptoms.

In Crohn’s disease, inflammation can affect any part of the GI tract - from the mouth to the anus - though it commonly develops in the end section of the small intestine and colon.

And what is IBS?

Irritable bowel syndrome (IBS), also known as irritable or spastic colon, is a collection of intestinal symptoms that often occur together. 

Unlike IBD, IBS is not classified as a disease, but it is considered a functional disorder, meaning that its symptoms have no identifiable cause. People with IBS often have normal test results. Other functional disorders include fibromyalgia, interstitial cystitis, and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

IBS is very common; according to the International Foundation for Functional Gastrointestinal Disorders, IBS affects at least 10-15% of American adults and is the most commonly diagnosed disorder by gastroenterologists.

How are IBD and IBS symptoms similar and different?

IBS and IBD can both be difficult diagnose because as long-term conditions, they share similar symptoms, including:

  • Abdominal cramps and pain
  • Nausea and/or vomiting
  • Diarrhea or constipation
  • Bowel urgency (urgent need for a bowel movement)

The two conditions are also often diagnosed in young people.

However, the chronic and long-term inflammation in IBD (and therefore in ulcerative colitis and Crohn’s) can cause symptoms that worsen with time, such as:

  • Loss of appetite or weight loss
  • Blood or black stool
  • Rectal bleeding
  • Intestinal scarring
  • Inflammation of the eyes, skin, or joints
  • Anemia

What causes IBS and IBD?

The causes behind both IBS and IBD are still not fully understood. 

In IBD, immune system malfunction (in which the immune system perceives harmless bacteria in the GI tract as foreign invaders and attacks) leads to chronic inflammation in the GI tract, causing symptoms such as bleeding, ulcers and pain. What is behind this abnormal immune response is not known.

This inflammation is not seen in IBS, so it is difficult for researchers to identify precise causes. Some research has identified a few contributing factors, such as over- or under-active muscle contractions in the intestinal tract, abnormalities or gaps in the signals between the gut and brain, severe infection (gastroenteritis) from bacteria or a virus, changes in the gut microbiome, or overexposure to stress in early life.

How are they diagnosed?


Because IBD is a structural disease, doctors look for physical damage in the GI tract to diagnose. Diagnostic tools used often include:

  • Blood and fecal tests (looking for markers of inflammation and other factors)
  • CT or MRI scans 
  • Colonoscopy (to view the inside of the intestines and/or to take a tissue sample (biopsy))

>> To learn more about blood tests for IBD, read our article: Inflammatory bowel disease (IBD): How to read your blood tests? <<


To diagnose IBS, doctors use the Rome criteria, a set of diagnostic criteria developed by the Rome Foundation, a non-profit organization dedicated to creating scientific data to help in the diagnosis and treatment of functional gastrointestinal disorders.

These criteria require that patients have had abdominal pain and discomfort lasting on average at least one day a week in the last three months, associated with at least two of following factors:

  • Pain and discomfort related to defecation,
  • Altered frequency of defecation
  • Altered stool consistency

In some cases these criteria are enough to diagnose IBD, but in cases of IBD-like symptoms blood, stool or other diagnostic tests will be used to eliminate IBD from the picture. 

How are they treated?


Treatment for IBD tends to target inflammation and treat symptoms, so it may include:

  • Anti-inflammatory drugs: NSAIDs, corticosteroids, aminosalicylates, etc.
  • Immune system suppressors: Methotrexate, cyclosporine, azathioprine, etc. 
  • Antibiotics: metronidazole, ciprofloxacin, etc.

Depending on the severity, some patients may also require surgery to remove damaged segments of the intestine, or in some cases removal of the entire colon and rectum.


There is no one, specific treatment plan for IBS. Treatments will often be symptom-focused and tailored to the patient. Commonly prescribed treatments include:

  • Education: This is often the first step in IBS treatment - in mild cases, IBS can be managed through dietary and lifestyle changes and stress management.
  • Medication: There is no singular medication for IBS, so the doctor and patient will work together to find medication(s) that ease symptoms. Antispasmodics such as dicyclomine (Bentyl) or hyoscyamine (Levsin) may be prescribed, among other medicines.
  • Psychological therapy: Some patients may find relief from sessions with a mental health professional, focusing on cognitive behavioral therapy (CBT), stress management, and/or relaxation therapy.

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