You’ve had tummy pain, bloating, and unpredictable bowel habits for months or years.
You’ve done the tests. Maybe a camera test. Bloods. A stool sample.
You’re told:
“It’s IBS.”
And that’s… it.
No cancer. No inflammatory bowel disease. No coeliac.
Reassuring on one level – but also a bit unsatisfying. Because you still feel awful, and “IBS” doesn’t actually tell you why your gut is misbehaving.
Let’s unpack what IBS is meant to mean, and why for some people it’s more of a broad label than a proper explanation.
What Doctors Mean by “IBS”
IBS = Irritable Bowel Syndrome.
In modern terms, it’s classed as a disorder of gut–brain interaction:
- Recurrent abdominal pain
- Linked to bowel habit (diarrhoea, constipation, or both)
- Often with bloating, wind, urgency
- No structural disease found on standard tests
Crucially, IBS is supposed to be a diagnosis of exclusion.
That means:
- First: rule out the serious stuff – bowel cancer, inflammatory bowel disease (Crohn’s, colitis), coeliac disease, significant infections.
- Then: if nothing nasty is found, symptoms fit the pattern, and criteria are met – IBS is a reasonable working diagnosis.
So far, that’s sensible and can be very reassuring.
The problem is what happens after the label is applied.
When “IBS” Becomes the End of the Conversation
In a pressured healthcare system, “IBS” can end up acting like a broad umbrella term:
“Your tests are normal, so it’s IBS. Here’s a leaflet. Try some fibre / Buscopan / peppermint.”
For some people, that’s fine – symptoms are mild, driven largely by stress or diet, and respond well to basic measures.
But for others, the label can feel like a full stop:
- Still in pain
- Still worried something is being missed
- Still with very real symptoms that don’t quite fit the simple picture
For those people, the question isn’t just “Do I have IBS?”
It’s:
“What’s actually driving my version of IBS?”
That’s where under-recognised mechanisms come in.
1. Autonomic Dysfunction – The Wiring Problem in the Background
Your autonomic nervous system controls all the automatic stuff:Heart rate
- Blood pressure
- Sweating
- Temperature control
- Bladder and bowel motility
If that system isn’t working smoothly, you can get:
- Palpitations
- Dizziness or feeling “swimmy” on standing
- Erratic blood pressure
- Heat/cold intolerance
- Bladder urgency or retention
- Gut chaos: diarrhoea, constipation, bloating, pain
There is no single, simple NHS tick-box test for “autonomic dysfunction”. Diagnosis is more about:
- Listening to the whole symptom pattern
- Checking relevant bloods (B12, iron, thyroid, glucose, etc.)
- Sometimes doing postural BP/heart rate checks, tilt testing, or cardiology input
- Ruling out other causes
If you only look at the bowel in isolation and never at the wider symptom pattern, you can easily end up calling it “IBS” while a broader dysautonomia picture is actually tying everything together.
2. SIBO – When Bacteria Move to the Wrong Postcode
SIBO = Small Intestinal Bacterial Overgrowth
In simple terms: bacteria that should mainly be living in the large intestine are overgrowing in the small intestine instead.
This can cause:
- Bloating that gets worse through the day
- Lots of gas
- Pain or discomfort
- Diarrhoea, or sometimes alternating stools
- Food-triggered flares, especially after carbs/sugars
Clinically, it can look almost identical to IBS. Many people with an IBS label are never specifically evaluated for SIBO.
Tests (like breath tests) exist, but:
- They’re not perfect
- Results need careful interpretation
- They’re not routinely done in standard care unless a clinician is specifically thinking about SIBO
So you can end up with SIBO wearing an IBS badge.
3. Gut Microbiome Imbalance – The Ecosystem Angle
Your gut microbiome is the community of bacteria, viruses, and other microbes in your gut.
We know:
- It influences motility, inflammation, immunity, and even mood.
- People with IBS often have different microbiome patterns compared with people without IBS.
We don’t know:
- One universal “ideal” microbiome profile for everyone.
- Which commercial microbiome tests meaningfully change management for most patients.
So yes, microbiome imbalance may be part of the picture, but it’s rarely as simple as “test + supplement = cure”. It’s another important factor, not the whole answer.
4. Bile Acid Malabsorption – The “IBS-D” Mimic
Bile acids help you digest fats. If too much bile acid spills into the colon, it can cause:
- Urgent, watery diarrhoea
- Often after meals
- Sometimes with sudden urgency that feels hard to control
Common situations:
- After gallbladder removal
- Sometimes with no obvious trigger
Tests (like SeHCAT in the UK) exist, but are not always offered early.
The result: bile acid diarrhoea can be labelled as IBS-D (diarrhoea-predominant IBS) for years if nobody considers this diagnosis.
5. Pancreatic Insufficiency – Digestion Problems in Disguise
Your pancreas produces enzymes that break down fat, protein, and carbohydrates.
If it’s underperforming (exocrine pancreatic insufficiency), you may get:
- Pale, bulky stools that are difficult to flush
- An oily sheen on the water
- Bloating and gas
- Weight loss or failure to gain weight
- Deficiencies in fat-soluble vitamins
If nobody steps back and thinks “pancreas”, this can be filed under “IBS” and treated with antispasmodics instead of enzyme replacement and further evaluation.
6. Lactose Intolerance – The Classic One That Still Gets Missed
Lactose intolerance happens when you don’t have enough lactase enzyme to break down the sugar in milk.
Typical pattern:
- Bloating, cramps, and diarrhoea
- After milk, ice cream, creamy sauces
- Often a few hours after eating
- Normal colonoscopy and blood tests → labelled “IBS”
Sometimes a simple, structured lactose reduction (not random restriction of everything) can dramatically improve symptoms. But if no-one looks for it, you stay stuck with an IBS label.
7. Non-Coeliac Gluten Sensitivity – The Awkward Middle Ground
You can have:
- Gut symptoms (bloating, diarrhoea, pain)
- Brain fog, fatigue, headaches, joint pains
- Triggered or worsened by gluten-containing foods
…but:
- Normal coeliac blood tests
- Normal endoscopy and biopsies
This is sometimes called non-coeliac gluten sensitivity.
It’s a complex and debated area. There’s overlap with:
- FODMAP intolerance (fermentable carbs rather than gluten itself)
- General reaction to ultra-processed foods
- Expectation and nocebo effects
For a subset of people, though, there is a genuine gluten-related pattern.
The key is a careful, structured elimination and reintroduction under guidance, not a lifetime of extreme restriction based on guesswork.
8. Severe Chronic Constipation – Disguised as “Mixed IBS”
A very common scenario
- Years of incomplete emptying
- Hard stools and straining
- Sensation of being “blocked”
- Then periods of looser stools or even leakage
That apparent “diarrhoea” can actually be overflow around hard stool sitting in the rectum.
If you don’t:
- Take a good history
- Examine appropriately
- Sometimes use imaging
…it’s very easy to badge this as “IBS mixed type” and miss the central issue: chronic constipation and slow transit, sometimes with pelvic floor problems.
So… Is IBS Ever a Real Condition?
Yes
There are plenty of people where:
- Serious disease is properly excluded
- Obvious hidden causes like those above are not present
- Symptoms clearly flare with stress, anxiety, poor sleep, and certain foods
- Gut motility and nerve sensitivity are the main drivers
That’s IBS as a genuine disorder of gut–brain interaction.
The difficulty is when the IBS label becomes:
“Your tests are fine, therefore nothing else can be explored.”
That’s not usually about individual doctors being careless; it’s about time pressure, limited appointment lengths, and system habits. But for the patient, the end result is the same: it can feel like the conversation has been cut short.
Red Flags: When It Must Not Just Be IBS
Whatever label you’ve been given, certain symptoms need urgent or specialist review:
- Unintentional weight loss
- Bleeding from the back passage or blood mixed in the stool
- Black, tarry stools
- Iron-deficiency anaemia
- A clear change in bowel habit after about age 50
- A lump or mass in the abdomen
- Persistent fevers, night sweats, or feeling very unwell
- A strong family history of bowel or ovarian cancer
These are not “wait and see” situations. They need timely assessment.
A More Thoughtful Approach to “IBS”
A careful clinician will usually think along these lines:
- Take a proper history
- Detailed symptoms, timing, triggers, extra-gut symptoms (palpitations, dizziness, bladder issues, fatigue, rashes, joint pains, etc.).
- Do an examination where appropriate
- Run appropriate baseline tests
- Bloods: full blood count, iron studies, inflammatory markers, coeliac screen, thyroid function, B12/folate as appropriate
- Stool tests: e.g. faecal calprotectin, infection screens, occasionally tests for pancreatic function, depending on the story
- Only after serious disease is excluded, consider:
- SIBO, bile acid malabsorption, pancreatic insufficiency, lactose intolerance, non-coeliac gluten sensitivity, chronic constipation, autonomic dysfunction, microbiome factors.
- Always factor in:
- Stress, trauma history, anxiety, depression, sleep, exercise, and diet as modifiers of gut function, not as excuses.
The goal is not to chase every possible test on day one, but to build a joined-up picture and investigate in a targeted way.
What You Can Do If You’ve Been Told “It’s Just IBS”
Some practical, grounded steps:
- Write your story down
- Symptoms, timing, food triggers, stress levels, menstrual cycle (if relevant), extra-gut symptoms.
- Get copies of your results
- Know exactly what’s been checked and what hasn’t. “All normal” is not a test name.
- Look for patterns
- Does it worsen with dairy? Wheat? Fatty foods? Artificial sweeteners?
- Does stress clearly flare it? Does travel or shift work play a role?
- Avoid random extreme diets and unsupported tests
- Super-restrictive diets and hundreds of pounds on unvalidated tests rarely help in the long term.
- Structured approaches (e.g. supervised low FODMAP, targeted trials of lactose reduction) are more useful.
- Consider a second opinion if you’re stuck
- Especially if your symptoms are severe, progressive, or life-limiting and you feel your concerns haven’t been fully explored.
A Calm Next Step
An IBS diagnosis should ideally be the start of a more thoughtful discussion, not the end of one. For some people, IBS as a gut–brain disorder is the right explanation. For others, the label may be sitting on top of something more specific and treatable.
If your gut symptoms haven’t been fully joined up with the rest of your health picture – things like palpitations, dizziness, temperature intolerance, or long-standing fatigue – you may benefit from a more holistic review of your autonomic system, bloods, and gut function rather than another generic IBS leaflet.
At Rubicon Private Health, this is the kind of structured, joined-up thinking a GP with an interest in gut and autonomic issues can offer: not magic, not grand promises, but a serious attempt to work out what’s really driving your version of “IBS”.
Disclaimer
This article is for general information only and is not a diagnosis or a substitute for medical advice. Bowel symptoms can have many causes, including serious conditions. Always discuss your own situation with your GP or a qualified healthcare professional before starting or changing any treatment.
