Irritable bowel syndrome

Irritable bowel syndrome is a disorder of gut–brain interaction. The bowel looks entirely normal under a camera and on a scan, and it is behaving differently: moving contents too fast, too slow or in an uncoordinated way, and reporting ordinary internal events as pain. A volume of gas or a degree of stretch that another person would not register at all is experienced as pressure, cramping or urgency.

Three mechanisms carry most of the explanation. Motility is altered, which is why stool form swings between hard pellets and urgent looseness, sometimes within the same week. Visceral sensitivity is heightened, so the threshold at which the gut sends a signal to the brain is lower than usual — this is the part that accounts for pain in an organ that is structurally intact. And gut–brain signalling is amplified in both directions. The gut has a dense nervous system of its own, running along the bowel wall and capable of coordinating movement without instruction from above, and it holds the great majority of the body's serotonin. Stress genuinely changes how it moves and how loudly it reports, and gut symptoms in turn change mood and sleep. This is a biological loop, not a euphemism.

Several other threads run through it. A substantial share of cases begin after an episode of gastroenteritis — post-infectious IBS — which is worth noting in a country where acute gut infections are common and where many people can date their symptoms to one specific illness. Low-grade immune activation in the bowel wall has been demonstrated in some people. The gut microbial community differs from that of people without IBS, though whether that is a cause or a consequence is unsettled. Bile acid malabsorption underlies a minority of diarrhoea-predominant cases and is under-recognised. Antibiotic courses and periods of significant stress are the other common starting points, and IBS clusters within families.

Worldwide, something like one adult in ten meets the criteria. Indian community studies generally report lower figures, often in the range of a few per cent, and how the question is asked accounts for much of that gap. Indian clinic populations also look somewhat different from the Western textbook description: constipation-predominant and mixed patterns are prominently reported, abdominal distension and a sense of incomplete evacuation are frequently the leading complaint, and the word most patients use for all of it is "gas". Several Indian hospital series describe men presenting more often than women, which is the reverse of the Western pattern and probably says as much about who reaches a gastroenterologist as about who has the condition.

One clarification, because the abbreviations are one letter apart and the confusion is common: IBS is not IBD. Inflammatory bowel disease — ulcerative colitis and Crohn's disease — involves visible inflammation and structural damage, and is a different condition with different treatment. IBS carries no increased risk of it, and none of bowel cancer.

ⓘThis information is educational and not a diagnosis.

The pattern matters more than any single symptom. IBS is recognised by recurrent abdominal pain — on average at least one day a week over the past three months — that is related to passing stool, or to a change in how often stool is passed, or to a change in its form. The symptoms have usually been present for six months or more by the time the diagnosis is made. That last criterion exists to prevent a label being applied to what is actually a three-week illness.

Around that core, most people describe bloating that builds through the day and settles overnight, urgency in the morning — often several trips within an hour of waking or of the first tea — a feeling of incomplete emptying, and mucus in the stool. Symptoms fluctuate over weeks and months rather than progressing steadily, and they characteristically do not wake people from sleep.

Subtypes are defined by the predominant stool form on the days when it is abnormal: constipation-predominant, diarrhoea-predominant, or mixed. This is worth being specific about rather than reporting as "my stomach is bad", because the treatments diverge sharply and the wrong one makes things worse. Describing the stool by its shape — pellets, sausage-shaped, soft pieces, watery — is more useful to a doctor than describing it by frequency.

Other things travel alongside often enough to be worth naming. Reflux and upper abdominal fullness overlap heavily with IBS, which is why one person can carry an antacid, a laxative and an antispasmodic in the same bag. Symptoms often intensify in the days before a period. Fatigue, poor sleep, headache and backache are common companions. And many people have narrowed their diet considerably by the time they arrive, usually without a clear record of what helped.

Two things about the Indian setting deserve mention. The first is that lactose tolerance falls with age in most Indian adults, so milk taken in quantity behaves differently from the milk of childhood — a matter of dose rather than a permanent verdict on dairy. The second is that "gas" is doing a great deal of work as a word here, describing bloating, belching, cramping, incomplete evacuation and reflux interchangeably. Separating what is actually happening is often the first useful step of the consultation.

The features listed below do not belong with IBS. They do not mean something serious is present, and they do mean the diagnosis is worth confirming rather than assuming.

The purpose of testing in IBS is narrow: exclude the small number of conditions that can look identical, and then stop. An open-ended search does not improve outcomes, and it reliably increases both cost and anxiety.

For most people the first pass is a full blood count with ferritin, CRP, coeliac serology and thyroid function. Anaemia or iron deficiency in this setting is a finding that needs its own explanation — coeliac disease is a common cause and unnoticed bleeding is the one that matters. Faecal calprotectin is added where diarrhoea is prominent, because it separates a functional gut from inflammatory bowel disease non-invasively and spares a great many colonoscopies. It is available at larger Indian laboratories rather than universally, costs more than the blood tests around it, and is still cheaper than the endoscopy it replaces.

Coeliac testing has one rule that is broken more often than any other in this area: it has to be done while wheat is still being eaten. A self-started gluten-free trial makes tissue transglutaminase antibodies unreliable for months and turns a straightforward question into a difficult one. Total IgA is measured alongside the antibody, because selective IgA deficiency produces a falsely reassuring result.

A stool examination for parasites belongs in the Indian version of this work-up more than in the Western one. Giardia in particular can produce months of bloating, loose stools and fatigue that read exactly like IBS, and it is treatable. Where the story began abruptly after an episode of gastroenteritis, a change in water supply or travel, it is worth doing rather than assuming.

Intestinal tuberculosis deserves a specific mention here for the same reason. It remains common in India, it can imitate both IBS and Crohn's disease, and it is one of the situations where weight loss, fever, night sweats or a steadily worsening course move the assessment out of this page entirely.

Colonoscopy is reserved for people with warning features, a first onset after 45, or a relevant family history. Breath testing for small intestinal bacterial overgrowth is used selectively; the preparation, the substrate and the cut-offs vary between centres, and the interpretation is considerably less settled than the marketing around it suggests. A hydrogen breath test for lactose is more straightforward, though for most people a two-week trial of reducing milk answers the same question at no cost.

Repeat ultrasounds and repeat endoscopies in someone with an established pattern and no new features are among the commonest unnecessary expenses in Indian gut practice. A test earns its place by changing a decision.

Treatment is aimed at the dominant symptom, and it is expected to be adjusted rather than got right at the first attempt. Most people end up with a small combination that suits them rather than a single answer.

The foundations, which are dull and effective. Regular meal timing rather than a long gap followed by a large dinner. Adequate water, particularly where constipation dominates. Moderating caffeine — four or five cups of tea a day is a meaningful dose — and alcohol. Regular physical activity has genuine trial evidence in IBS, modest but real. Sleep is not a soft add-on here; short sleep raises gut sensitivity the way it raises everything else.

Diet, in an Indian kitchen. A structured low-FODMAP approach helps a majority of people, and it works as designed only when it is time-limited: two to six weeks of restriction, then systematic reintroduction to find individual thresholds. Done indefinitely it narrows the diet, alters the microbiome and rarely improves anything further. Translated into Indian food, the higher-FODMAP items are wheat, rajma, chana, chole and whole dals, onion and garlic, milk, and fruits such as mango, apple and watermelon. Better tolerated, generally, are rice, moong dal in modest quantity, fermented preparations such as idli and dosa, curd, paneer, potato, carrot, spinach and firm banana. Two practical notes: onion and garlic form the base of most Indian gravies, so replacing them with asafoetida and ginger achieves more than any other single substitution, and households that already cook without them may find they have less to change than they feared. Because pulses are both high in FODMAPs and the main source of protein in a vegetarian diet, doing this without guidance tends to produce a diet that is low in protein and impossible to sustain.

Fibre, chosen by type. Soluble fibre — psyllium, sold in every Indian chemist as isabgol — helps constipation-predominant IBS and is inexpensive. Insoluble fibre, particularly wheat bran, commonly makes bloating and pain worse, which is why the general advice to eat more fibre sometimes backfires here.

Symptom-directed medicines, explained rather than prescribed. Antispasmodics reduce cramping pain. Enteric-coated peppermint oil has reasonable evidence for pain and bloating. Osmotic laxatives such as polyethylene glycol are used in constipation-predominant IBS; lactulose, though widely prescribed, ferments and often worsens bloating in exactly the people who already have it. Loperamide has a role in diarrhoea-predominant symptoms. Rifaximin, an antibiotic that stays within the gut, has trial evidence in diarrhoea-predominant IBS and bloating, and is given in defined courses. Low-dose neuromodulators — tricyclics for diarrhoea-predominant symptoms, SSRIs where constipation dominates — are used for pain and gut sensitivity at doses well below those used in depression, and prescribed for that reason rather than because the symptoms are considered psychological. Which of these fits your pattern is a decision with your doctor.

The gut–brain side, which is not an afterthought. Gut-directed cognitive behavioural therapy and gut-directed hypnotherapy have an evidence base in IBS comparable to dietary change. Access in India is limited outside the larger cities, and structured app-based programmes have made this considerably more reachable than it was. Where symptoms flare predictably around work pressure, examinations or family stress, this is treating the mechanism rather than working around it.

A diary that earns its keep. Two weeks of recording what was eaten, what happened, and what else was going on tells you more than any printed list of forbidden foods. Recording sleep, stress and, where relevant, the menstrual cycle alongside food is what turns a food diary into a useful one.

Follow-up. A review at six to eight weeks to judge what worked, adjust what did not, and set expectations honestly. The realistic aim is control and predictability: shorter flares, longer quiet periods, and a clear plan for the next one.

Most of the difficulty with IBS is not knowing what is happening. It is knowing which of the many available approaches to try, in what order, and for how long before deciding it has not worked — and being told the reports are normal without being told what that leaves.

Because the same sensitive gut so often produces reflux, bloating and unpredictable bowels at once, the Learning Session below covers them together in a small group, including how to run a food and symptom diary that actually tells you something.

If your pattern does not fit neatly, if the features listed above are present, or if you have been managing this alone for years with a drawer full of half-finished medicines, that is a conversation for a consultation rather than an article.