IBS and Functional Gut Symptoms — Diagnosis, Red Flags and Treatment
TL;DR — Irritable bowel syndrome (IBS) is a chronic disorder of gut-brain interaction — abdominal pain and altered bowel habits in the absence of any structural disease. It is extremely common (affecting around 10–15% of Australians), it is not dangerous, and it does not progress to bowel cancer. The diagnosis is clinical, made after structural disease has been ruled out where appropriate. Treatment is a stepwise combination of lifestyle change, dietary work (low-FODMAP), pharmacotherapy and sometimes psychological strategies. Dr Goutham investigates and excludes structural causes; chronic IBS management is usually shared with the GP.
What is IBS?
Irritable bowel syndrome is a functional condition — the bowel itself looks normal at endoscopy and on imaging, but the way it senses and moves food is disordered. Symptoms come from a combination of altered motility, visceral hypersensitivity (increased pain signalling from the gut), changes in the gut microbiome, and influence of the gut-brain axis (stress, anxiety, and prior gastrointestinal infection all play roles).
IBS is sub-classified by predominant bowel habit:
- IBS-D — diarrhoea predominant
- IBS-C — constipation predominant
- IBS-M — mixed, alternating
- IBS-U — unclassified
Symptoms
- Recurrent abdominal pain — often relieved by bowel movement or associated with a change in stool form / frequency
- Altered bowel habit (diarrhoea, constipation, or alternating)
- Bloating, abdominal distension
- Mucus in the stool
- Symptoms triggered by stress, certain foods (FODMAPs), menstrual cycle
- Sense of incomplete evacuation
Red flags — symptoms that mean it is not IBS until proven otherwise
None of the following are explained by IBS; they always warrant investigation:
- Onset of symptoms after age 50
- Unintentional weight loss
- Rectal bleeding or melaena (black tarry stool)
- Iron-deficiency anaemia
- Nocturnal symptoms (waking from sleep with pain or diarrhoea)
- Fever
- Family history of bowel cancer, coeliac disease, or inflammatory bowel disease
How is IBS diagnosed?
IBS is a positive clinical diagnosis — usually made using the Rome IV criteria: recurrent abdominal pain on average at least 1 day per week in the last 3 months, associated with two or more of: relation to defaecation, change in stool frequency, change in stool form. Symptoms must have started at least 6 months earlier.
Investigations are tailored to the individual. Common baseline tests include FBC, ferritin, CRP, coeliac serology, TSH, and faecal calprotectin (a marker of bowel inflammation that helps distinguish IBS from IBD). Colonoscopy is recommended in the presence of any red flag, in anyone over 45, and after a positive FIT — primarily to rule out other diagnoses rather than to diagnose IBS itself.
How is IBS treated?
Treatment is stepwise, individualised, and often requires trial-and-error:
- Lifestyle — regular meals, adequate fluid, regular exercise, sleep, stress management
- Low-FODMAP diet — a structured 6–8 week elimination of fermentable carbohydrates (FODMAPs) followed by reintroduction, ideally done with an accredited dietitian. Effective in around 50–70% of patients with IBS
- Soluble fibre (psyllium) for IBS-C; reduce insoluble fibre (wheat bran) for IBS-D
- Antispasmodics (mebeverine, hyoscine) for pain
- Laxatives for IBS-C (osmotic, stimulant, or prosecretory)
- Anti-diarrhoeals (loperamide) for IBS-D
- Low-dose tricyclic antidepressants (amitriptyline 10–25 mg) — work on visceral hypersensitivity, not on mood, and are highly effective for pain
- Cognitive behavioural therapy, gut-directed hypnotherapy, mindfulness
- Probiotics — selected strains have evidence for bloating and pain
- Rifaximin for IBS-D with bloating; eluxadoline; ondansetron in selected cases
When to see a specialist
- Any red flag symptom (see above)
- New IBS-like symptoms after age 50
- Symptoms not controlled by standard GP-led management
- Significant impact on work, sleep or quality of life
- Family history of bowel cancer, IBD or coeliac disease
- Refractory IBS-D or IBS-C requiring specialist medication
What to expect at your appointment with Dr Goutham
Dr Goutham’s role in IBS is usually to rule out structural disease (colonoscopy ± gastroscopy where appropriate) and then to confirm the diagnosis and outline the treatment plan. Most chronic IBS management is then handed back to the GP, with the specialist available for review when treatment fails or red flags emerge. Investigation choices depend on age, red flags, family history and prior tests. A typical first consult reviews symptoms, prior tests, and arranges any further investigation; a follow-up consult explains findings and sets the treatment pathway.
Frequently asked questions
Will IBS turn into bowel cancer?
No. IBS does not cause bowel cancer or progress to it. The reason a colonoscopy is sometimes recommended in IBS is to exclude other diagnoses, not because IBS itself becomes dangerous.
Is the low-FODMAP diet a long-term diet?
No. Low-FODMAP is a diagnostic and learning diet, not a long-term dietary pattern. The full protocol is: strict elimination for 6–8 weeks, then structured reintroduction over 6–10 weeks to identify which FODMAPs trigger your symptoms, then a personalised long-term diet that includes everything you tolerate. Working with an accredited dietitian familiar with FODMAPs is strongly recommended.
Are probiotics worth trying for IBS?
Some specific strains have evidence for symptoms like bloating and abdominal pain — including some Bifidobacterium and Lactobacillus formulations. A reasonable approach is a 4–6 week trial of a single, well-characterised product; continue if helpful, stop if not.
Book a consultation
Phone 07 3733 1551 or send a referral via the contact form. See about Dr Goutham or the cost page.
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