IBS vs IBD
Side by side
| IBS | IBD (Crohn's, ulcerative colitis) | |
|---|---|---|
| What it is | Disorder of gut-brain interaction | Immune-mediated inflammatory disease |
| Tissue damage | None. The bowel looks normal | Yes. Visible inflammation and ulceration |
| Blood in stool | Not a feature | Common, especially in colitis |
| Wakes you at night | Characteristically not | Often does |
| Weight loss | Not expected | Common |
| Fever | No | Can occur in a flare |
| Outside the gut | No | Joints, eyes, skin, mouth ulcers |
| Calprotectin | Normal | Raised |
| Confirmed by | Clinical criteria, after excluding other causes | Colonoscopy with biopsies, plus imaging |
| Treatment | Symptom management: diet, psychological therapies, some medication | Medical treatment to suppress inflammation |
| Risk of not treating | Quality of life | Bowel damage, surgery, complications |
The test that does most of the separating
Fecal calprotectin. Calprotectin is a protein released by neutrophils, the white blood cells that turn up where there is inflammation. When the bowel wall is inflamed they migrate into the gut and the protein appears in stool. In IBS there is no inflammation, so it stays low.
It is cheap, needs only a stool sample, and is widely available through primary care. A low result is genuinely reassuring and makes IBD unlikely. A raised result is not a diagnosis, but it is a clear reason to investigate rather than to start an elimination diet. This is one of the five tests we rate as worth doing in which gut tests are actually worth it.
Note that the direction of concern is inverted compared with most tests people buy: the expensive consumer panels return long lists that change nothing, while this modest test can change your entire treatment path.
Why the distinction is urgent rather than academic
IBS does not damage you. It can be thoroughly disabling and it deserves to be taken seriously, but the tissue is intact and a delay in diagnosis costs you time and quality of life rather than bowel.
IBD is different. Untreated inflammation causes cumulative damage: strictures, fistulas, an increased need for surgery, and in long-standing colitis an increased cancer risk. Time matters. Someone managing undiagnosed IBD with a food diary and a low FODMAP app is the single worst outcome anything on this site could contribute to, which is why every symptom page here routes red flags to a clinician rather than to a tracker.
Having both, which is more common than people expect
A substantial share of people with IBD in remission, with no measurable inflammation, still have IBS-type symptoms. That is not a failure of their treatment and it is not imaginary. It is a hypersensitive gut on top of a healed one, and it responds to the things IBS responds to.
The practical implication is that symptoms alone cannot tell you whether your IBD is active. If you have IBD and feel worse, the question "is this inflammation or is this IBS" is answered by testing, not by how bad it feels, and the two answers lead to completely different actions.
Where tracking fits, and where it does not
Once inflammation has been excluded or is being treated, a food and symptom record is useful for the same reasons it is useful in IBS: it establishes your own base rate and lets you test suspects properly instead of narrowing your diet on impressions. For IBD specifically, a dated record of symptom frequency and stool form is also genuinely useful to your gastroenterology team, who are otherwise relying on your recall between appointments.
What it is not is a substitute for calprotectin, a scope, or treatment. Minthe does not detect inflammation and cannot tell you whether you are in remission.
Minthe is a wellness and self-tracking tool, not a medical device. It does not diagnose or treat any condition and isn't a substitute for professional medical advice. If you have red-flag symptoms such as blood in your stool, unintentional weight loss, difficulty swallowing, persistent vomiting or a fever alongside gut symptoms, see a clinician rather than tracking them.
Sources
- von Roon AC, et al. Diagnostic precision of fecal calprotectin for inflammatory bowel disease and colorectal malignancy. American Journal of Gastroenterology, 2007;102(4):803-13. PubMed
- Rubin DT, et al. ACG Clinical Guideline: Ulcerative Colitis in Adults. American Journal of Gastroenterology, 2019;114(3):384-413. PubMed
Frequently asked
What is the difference between IBS and IBD?
IBS, irritable bowel syndrome, is a disorder of gut-brain interaction. The gut is hypersensitive and its motility is altered, but the tissue itself is not damaged and looks normal on a scope. IBD, inflammatory bowel disease, is a group of immune-mediated conditions, mainly Crohn’s disease and ulcerative colitis, in which the immune system attacks the bowel and causes visible inflammation and ulceration. IBS is miserable but does not damage you. IBD damages the bowel and needs medical treatment.
Can a stool test tell them apart?
Fecal calprotectin does most of the work and it is the single most useful test in this area. Calprotectin is a protein released by white blood cells in the gut wall, so it rises when there is real inflammation and stays low in IBS. It is inexpensive, non-invasive, widely available, and a low result is genuinely reassuring while a raised one is a reason to investigate further. It is not a diagnosis on its own, and a colonoscopy is what confirms IBD.
What symptoms suggest IBD rather than IBS?
Blood in the stool, symptoms that wake you from sleep, unintended weight loss, fever, mouth ulcers, joint pain, eye inflammation, anemia, or a family history of IBD. Nocturnal symptoms are particularly worth knowing about: IBS characteristically does not wake people up, so being woken by pain or the need to open your bowels is a genuine differentiator and one that patients rarely think to mention.
Can you have both IBS and IBD?
Yes, and it is common enough that it has a name in the literature. Many people with IBD in remission, with no active inflammation on testing, continue to have IBS-type symptoms. That is a real and treatable situation, and it is why someone with IBD whose symptoms persist should have inflammation re-checked rather than assumed: the answer changes completely depending on whether calprotectin is raised.
Does diet cause IBD?
No. IBD is immune-mediated and diet does not cause it, which is an important thing to be clear about because the internet suggests otherwise. Diet can influence symptoms, and nutrition matters a great deal in managing IBD, but no elimination diet treats the underlying inflammation and none should replace medical treatment. This is the main reason we would not point someone with suspected IBD at a food diary as a first step.