No two digestive issues are confused with each other more than IBS and IBD. The problem begins with their strikingly similar acronyms. The overlapping symptoms — abdominal pain and diarrhea — don't help either.
But IBS and IBD are distinct issues. If you think you might have one or the other, it's important to determine exactly which it might be.
"The key to understanding the difference between IBD and IBS is to know what they stand for," says Dr. Bincy Abraham, a gastroenterologist at Houston Methodist. "I've seen every different combination of words put together for each, which really confuses the matter."
IBD stands for inflammatory bowel disease. IBS stands for irritable bowel syndrome.
Once you have the names correct, you can see the primary distinguishing factor right away: inflammatory versus irritable. The two terms may sound similar, but they're different. Both cause uncomfortable symptoms, but the inflammation that accompanies IBD can lead to serious complications if left untreated.
"It's very important to distinguish between the two so we're not undertreating IBD or overtreating IBS or vice versa," says Dr. Abraham.
What is IBD?
"Inflammatory bowel disease is a chronic condition where there's inflammation in the small or large bowel, and sometimes even the upper GI tract," explains Dr. Abraham. "It's an immune-mediated condition, meaning the immune system is overreacting, leading to a chronic inflammatory process."
There are two types of IBD:
- Ulcerative colitis – inflammation in the large bowel (also called the large intestine) and rectum
- Crohn's disease – inflammation that occurs anywhere in the GI tract, most commonly in the small and large intestine
IBD symptoms vary depending on the type, but common ones include:
- Diarrhea
- Abdominal pain
- Rectal bleeding
- Fatigue
- Weight loss
What is IBS?
Simply put, IBS is when your bowels are irritated for one reason or another.
"This irritation leads to abdominal pain and alterations in bowel habits, but none of the inflammation we see with IBD," explains Dr. Abraham. "It's more of a symptomatic syndrome, rather than a disease."
IBS symptoms include:
- Abdominal pain
- Cramping, bloating and increased gas
- Diarrhea
- Constipation
- Alternating diarrhea and constipation
The syndrome is fairly common. Estimates suggest up to 20% of Americans suffer from IBS, of which only around 15% seek medical help. The triggers of IBS are common, too — ranging from stress to foods to changes in the gut microbiome.
IBD vs. IBS: How to tell the difference
Because IBD and IBS share a few overlapping symptoms, it's crucial to consult your doctor so a correct diagnosis can be made.
"The gold standard for assessing the bowel is through colonoscopy, since this allows us to visualize the tissue lining and assess for inflammation," says Dr. Abraham. "If you have IBD, we'll see evidence of inflammation such as redness, ulcerations or bleeding. If you have IBS, there won't be any visual changes to bowel linings, your colon will visually look normal."
Biopsies can also be collected at this time. The chronic inflammation associated with IBD can also be seen under a microscope as a pathologist analyzes tissue samples.
That said, Dr. Abraham stresses that not every person experiencing diarrhea and abdominal pain needs to go through an invasive procedure like a colonoscopy.
"Fortunately, we have noninvasive ways of assessing IBD from IBS," says Dr. Abraham. "For instance, we can first check for inflammatory markers via a stool sample."
It's often the first test performed when it's unclear if a person's symptoms are caused by IBS or IBD.
"If inflammatory stool markers are elevated, that would warrant proceeding with additional workup, like a colonoscopy," explains Dr. Abraham. "This helps ensure we're not missing a diagnosis of IBD but also not overtesting in people who have IBS."
Why differentiating between IBS and IBD is important
Like any other health issue, a correct diagnosis is essential to receiving the right treatment.
"We treat IBS symptomatically," says Dr. Abraham. "For instance, anti-diarrheal medications are recommended to help manage diarrhea. Pain relievers can help with abdominal pain."
For someone who's predominantly experiencing constipation, lifestyle changes will be needed, including increasing fiber intake, and laxatives may be even be recommended.
IBD, on the other hand, is a chronic disease that requires treating the root cause — inflammation.
"Treatment requires anti-inflammatory medication," explains Dr. Abraham. "Whether we use oral tablets, suppositories or newer, stronger options like biologic and small molecule therapies, the goal of IBD treatment is to reduce inflammation so the tissue lining can heal."
It's critical to treat IBD because uncontrolled inflammation in the bowel can lead to serious complications, such as bowel obstructions, fistulas, anal fissures and more.
"IBD also increases the risk of colorectal cancer," says Dr. Abraham. "This is important information to know since it will affect your colorectal cancer surveillance recommendations."
Because IBD may cause flare-ups, it's also important to work with your doctor to ensure inflammation remains under control with treatment.
"One neat thing we can do today is use intestinal ultrasound to noninvasively assess the bowel linings for signs of inflammation," says Dr. Abraham. "For instance, if I have an IBD patient who's experiencing diarrhea, we can do an ultrasound and determine whether it's an IBD flare-up or something else, such as IBS."
Unlike a colonoscopy, an intestinal ultrasound can be performed in the clinic during your appointment. Ultrasounds also provide immediate results, an advantage over stool samples, which can take a few days to process.
