What’s Really Going on Inside the Gut?

Inside the gastrointestinal tract, there are two distinct disorders that commonly are lumped together as one, of course, referring to irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). For most, it’s understandable to do this, as they do have some similar symptoms, but they are not the same condition. It’s uberly important to note what differences they have, because the treatments are very different and otherwise would not be managed correctly.

Irritable Bowel Syndrome Overview

IBS is a functional gastrointestinal disorder, headlining a disturbance in bowel function. It does not cause inflammation, and rarely requires hospitalization or surgery. Upon an exam of the colon, there is no sign of disease or abnormality present. With IBS, a patient does not have an increased risk for being diagnosed with colon cancer or IBD. IBS is broken up into two categories, IBS-constipation (IBS-C) and IBS-diarrhea (IBS-D). 

Symptoms can be triggered by ordinary stimuli, including foods, stress, hormonal shifts, and certain medications. Spasms can work in both ways, speeding up or slowing down gut motility, which could lead to either diarrhea or constipation. Here are some common symptoms of IBS:

Diagnosing IBS is difficult, since it’s unable to be found on a visual examination or with diagnostic procedure tools. A physician may use blood and stool tests, x-rays, endoscopies, and psychological tests to rule out any other diseases. Additional criteria for diagnosis includes having abdominal discomfort or pain for at least 12 weeks, even if non-consecutive, over the past 12 months, accompanied by at least two of the following:

It is not fully understood what the cause of IBS is, though those with IBS often have irregular colon motility patterns, meaning muscle contractions between the brain and the GI tract are working improperly.

Inflammatory Bowel Disease Overview

IBD is a chronic inflammatory disease of the GI tract, divided into Crohn’s disease (CD) and ulcerative colitis (UC). CD, resulting in transmural ulceration of any GI tract portion, most often affects the terminal ileum and colon while UC, involving diffuse inflammation, affects the rectum but may also extend into the sigmoid, beyond the sigmoid, or include the entire colon up to the cecum. Both are classified by extent and location, with CD also being categorized by phenotype: inflammatory, stricturing, or penetrating. 

IBD occurs in genetically susceptible individuals after an inappropriate immune response to the intestinal flora. Unfortunately, neither is a curable disease, and these can bring about serious morbidity risk, and a raised risk of colorectal cancer complications. A root cause, though, is not universally present in all patients. Smoking is an interesting conundrum, as it has a strong link to CD, but appears as a protectant against UC. Lastly, as far as a cause goes, the CARD15 gene has been connected to IBD, but because of its polymorphic features, it is not possible to determine which location(s) inside the GI tract will be affected. 

So, what are some signs and symptoms to look out for to diagnose a patient with IBD? Here are the most common symptoms, according to the World Gastroenterology Organization:

Image: CDC. Available at: https://www.cdc.gov/inflammatory-bowel-disease/about/crohns-disease-basics.html

IBS Treatment

Let’s look into how these two are treated. First, back to IBS. IBS treatment is targeted at symptom relief and improving overall quality of life. Split into IBS-C and IBS-D, as these have different treatments. 

To begin, describing some treatments for IBS-C include the following:

Image: Unsplash. Available at: https://unsplash.com/photos/fruit-lot-on-ceramic-plate-8manzosDSGM

Now, moving into IBS-D and the following treatments: 

For overall symptoms, there are some additional medication classes or lifestyle adjustments that can be implemented as well. Some of these options include antispasmodics, selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs), dietary modifications, probiotics, fecal microbiota transplant, behavioral therapies, complementary and alternative medicine (CAM). Simply put, IBS-C and IBS-D treatment comes in a multifactorial approach. They prioritize different mechanisms of action, but commonly see the opposite condition as a side effect, which can be minimized by other methods, such as taking IBS-C medications with food.

Image: Created on Google Docs

IBD Treatment

For Crohn’s Disease, the main goal of treatment is mucosal healing on endoscopy. Furthermore, treatment is based on severity level, outlined as follows.

Ulcerative Colitis (UC) treatment is centered around sustained and durable steroid-free remission, appropriate psychosocial support, normal quality of life and social functioning, prevention of morbidity including hospitalization and surgery, and lastly prevention of cancer. UC treatment options are complicated, featuring dozens of steps up in treatment depending on treatment failures, contraindications, disease severity level, etc. Treatment choices are based on the GRADED methodology per the American College of Gastroenterology (ACG). Featured drug classes include, but are not limited to:

Resealing our Divide

IBS and IBD at their core, seem very similar, though, they are not. While they share a few characteristics, it should now be more clear on where they differ, how to spot differences between the two, and why these differences are important. Both can very easily interrupt quality of life, patient comfort, trigger anxiety and depression symptoms, and much more. It’s imperative that each of these conditions are diagnosed correctly, treated appropriately with medications and lifestyle changes, monitored by providers, and follow ups are completed.

Image: CDC. Available at: https://www.cdc.gov/inflammatory-bowel-disease/about/#cdc_disease_basics_symptoms_mngmt-medication-and-managing-symptoms

Collin B., APPE Student

References: 

1. Crohn’s & Colitis Foundation. IBS vs IBD. Crohn’s & Colitis Foundation. Published 2025. https://www.crohnscolitisfoundation.org/patientsandcaregivers/what-is-ibd/ibs-vs-ibd
2. McDowell C, Farooq U, Haseeb M. Inflammatory Bowel Disease (IBD). PubMed. Published August 4, 2023. https://www.ncbi.nlm.nih.gov/books/NBK470312/
3. Tetali B, Suresh S. Management of irritable bowel syndrome: A narrative review. Translational Gastroenterology and Hepatology. 2024;9(9):26.
4. Updated 2025 ACG clinical guideline for the management of Crohn’s disease – American College of Gastroenterology. American College of Gastroenterology. Published 2025. https://gi.org/journals-publications/ebgi/zhai_dalal_sep2025/
5. The updated 2025 ACG guidelines to manage adult ulcerative colitis patients – American College of Gastroenterology. American College of Gastroenterology. Published August 20, 2025. https://gi.org/journals-publications/ebgi/alkazzi_aug2025/