Irritable bowel syndrome (IBS, in German "Reizdarmsyndrom", RDS) is a functional bowel disorder — the bowel does not work properly, but there are no visible inflammations, ulcers or tissue changes as in Crohn's disease or ulcerative colitis. Standard examinations are usually unremarkable, but the burden of suffering can nevertheless be considerable.
According to the current S3 guideline, irritable bowel syndrome is usually present when three criteria are met: the symptoms have existed for at least three months or recur regularly, they relevantly impair quality of life, and there is no other illness that sufficiently explains the symptoms.¹
IBS is not imagined
According to current knowledge, irritable bowel syndrome is usually not dangerous and mostly does not increase the risk of bowel cancer. The burden of suffering is nevertheless real and can considerably restrict quality of life.
2. Symptoms and subtypes
Typical main symptoms
Abdominal pain or cramps — often in the lower abdomen, wave-like; improvement after a bowel movement is typical
Bloating, a distended abdomen (distension) and flatulence — for many the most burdensome symptom
Changes in bowel habits: diarrhea, constipation or both alternating
Nausea, a feeling of incomplete evacuation, mucus in the stool
Depressive mood or anxiety — IBS and mental illnesses often occur together
Frequent overlap with functional dyspepsia, fibromyalgia or persistent exhaustion
The four subtypes
IBS-DDiarrhea type
In the foreground are more frequent, often watery bowel movements, a pronounced urge to defecate and sometimes a fear of having a bowel movement in certain situations. Symptoms are often stronger in the morning and after eating.
IBS-CConstipation type
In the foreground are hard, infrequent bowel movements and a feeling of incomplete evacuation. Bloating is often the dominant accompanying symptom.
IBS-MMixed type
Diarrhea and constipation alternate — sometimes within a few days.
IBS-BBloating type — newly identified in the current guideline
Bloating and a distended abdomen are in the foreground. Often considered a particularly difficult-to-treat subtype.¹
Warning signs — not pure irritable bowel syndrome, medical evaluation needed:
Blood in the stool · Unintentional weight loss · Fever · Night sweats · Symptom onset at an older age · Family history of bowel cancer or IBD · Anemia. In such situations, a colonoscopy, among other things, is usually recommended.
3. Causes: the gut–brain axis
The exact cause of IBS is not fully understood — it is usually an interplay of several factors.¹
Disturbed gut–brain axis: The communication between the brain and the gut is often oversensitive. The gut sends amplified pain and discomfort signals to the brain (visceral hypersensitivity). Stress can additionally amplify these signals.
Altered gut motility: Bowel movement that is too fast → diarrhea; too slow → constipation. In many people with IBS, uncoordinated bowel movements are seen.
Changes in the gut microbiome: An altered composition of the gut bacteria (dysbiosis) is discussed as a possible contributing factor — this is where probiotics and the low-FODMAP diet, among others, come in.
Post-infectious IBS: In some of those affected, IBS begins after a gastrointestinal infection. The risk usually rises with the severity of the infection.¹
Stress and psychological factors: Stress is considered one of the most common triggers. Anxiety and depression occur more often together with IBS — this does not mean IBS is "only psychological". The gut–brain axis works in both directions.
Food hypersensitivities: A sensitivity to FODMAPs, lactose or fructose can amplify the symptoms — usually not classic allergies.
4. Diagnosis — a diagnosis of exclusion
There is no single test that proves irritable bowel syndrome. The diagnosis is made when the clinical criteria are met and major other illnesses have been excluded.¹
Basic diagnostics
Blood count, inflammation values and thyroid values (TSH)
Calprotectin in the stool — an important test to distinguish a chronic inflammatory bowel disease
Test for occult blood in the stool (iFOBT)
If suspected: lactose or fructose breath test
Extended diagnostics
Colonoscopy — with warning signs, first manifestation at an older age, family history or a lack of response to treatment; not strictly necessary in young patients with a typical IBS picture
Ultrasound of the abdomen
In women with lower abdominal pain: gynecological evaluation (among other things to exclude endometriosis)
Make the diagnosis positively — don't search for years
The diagnosis of irritable bowel syndrome should be made positively as early as possible — based on the clinical criteria and after excluding relevant differential diagnoses — not only after years of burdensome diagnostics.
A change in diet is one of the most effective approaches for IBS and can in many cases be as effective as medication. The current S3 guideline recommends a low-FODMAP diet, especially for abdominal pain, bloating and diarrhea — usually under the guidance of a dietitian.¹
FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols — short-chain carbohydrates that are poorly absorbed in the small intestine in some people and can cause gas, water influx, bloating or diarrhea in the large intestine.
The 3-phase model
Phase 1Elimination — avoid FODMAP-rich foods
For a limited period, FODMAP-rich foods are avoided as consistently as possible:
FODMAP-rich — avoid in phase 1
Wheat (fructans), rye
Onions, garlic
Apples, pears, cherries, watermelon
Dairy products containing lactose
Legumes (lentils, beans)
Certain types of cabbage and mushrooms
Sugar substitutes (sorbitol, mannitol) in "sugar-free" products
FODMAP-low — usually well tolerated
Rice, quinoa, oats
Potatoes, carrots, zucchini, peppers
Strawberries, blueberries, oranges, bananas
Lactose-free dairy products
Firm tofu, chicken, fish
Spring onions (green part)
Almonds in small amounts
Phase 2Reintroduction — test individual tolerance
Individual FODMAP groups are gradually reintroduced to test individual tolerance. Experience shows that many of those affected tolerate some of the groups well.
Phase 3Long-term diet — individual and varied
In the long term, only the individually intolerable FODMAPs are restricted. The goal is as varied a diet as possible — a permanent strict elimination is usually not recommended, in order to prevent malnutrition and an impoverishment of the microbiome.
Always do the FODMAP diet with guidance
The low-FODMAP diet should be carried out under the guidance of a dietitian. A permanent strict elimination without guidance can lead to malnutrition and is usually not sensible.
Further dietary tips
Keep a food diary — individual triggers can often only be identified over time
Small, regular meals instead of a few large portions
Eat slowly and chew well
Fiber: soluble fiber (e.g. psyllium) helps with constipation; insoluble fiber (e.g. wheat bran) is often poorly tolerated with pronounced bloating
Drink enough — especially important in combination with psyllium
Caffeine, alcohol and strongly carbonated drinks can amplify symptoms
6. Medication: symptom-oriented
There is no single medication that "cures" irritable bowel syndrome. Drug therapy is usually oriented towards the symptoms — depending on the dominant clinical picture.¹˒²
Cramps and pain
Peppermint oil (enteric-coated capsules) — positively recommended in the S3 guideline
The current S3 guideline gives a positive recommendation for enteric-coated peppermint oil capsules for cramps and bloating. Usually well tolerated; many products are available without a prescription.¹
Butylscopolamine
An antispasmodic medication that can relax the bowel musculature. Often used as needed. Available without a prescription.
Mebeverine
Has an antispasmodic effect on the bowel and usually has fewer anticholinergic side effects than butylscopolamine.
STW 5 (Iberogast)
A plant combination that can act on several symptoms at once. An option for some of those affected — always in consultation with a doctor or pharmacy.
Diarrhea-dominant type (IBS-D)
Loperamide
Slows the bowel passage. Usually used as needed — not prophylactically over long periods. Can cause constipation with frequent use.
Bile acid binders (e.g. colesevelam)
When bile-acid-related diarrhea is suspected. Considered more strongly in the current guideline than in earlier versions.¹
Rifaximin
An antibiotic that acts locally in the bowel. An option for difficult-to-treat, non-constipated IBS. The decision is usually made by a gastroenterology specialist.
Constipation-dominant type (IBS-C)
Macrogol — recommended in the S3 guideline
An osmotic laxative that binds water in the bowel and softens the stool. The current guideline recommends macrogol for IBS-related constipation. Usually well tolerated, even over a longer period.¹
Psyllium husks
Soluble fiber that swells in the bowel and can regulate stool consistency. Important: always take with enough fluid.
Linaclotide (prescription-only)
For adults with moderate to severe IBS with constipation. In addition to regulating stool, it can also affect pain and bloating.¹
Prucalopride
A prokinetic medication that can speed up the bowel passage. Usually used for difficult-to-treat chronic constipation.
Bloating
Simeticone/dimeticone — so-called antifoaming agents; effectiveness not clearly proven, but tolerability is good. Many products available without a prescription.
Peppermint oil and linaclotide (see above) can also act on bloating.
Low-dose antidepressants for difficult-to-treat IBS
In difficult-to-treat cases, low-dose antidepressants are occasionally used — not primarily because of a depression, but because of their modulating effect on the gut–brain axis. Tricyclic antidepressants are more often considered for the diarrhea-dominant type, SSRIs rather for the constipation-dominant type or with accompanying anxiety/depression. The decision is always made by the treating doctor.¹
The S3 guideline gives a generally positive recommendation for probiotics in IBS — but with important limitations:¹
Not all probiotics work the same — the effect is usually strain-specific
Positive effects described especially for bloating and abdominal pain
Prebiotics are not recommended for IBS — they can sometimes even worsen bloating
A stool transplant (fecal microbiome transfer) is currently not recommended for IBS outside of studies
Practical tip
If a probiotic is tried, a consistent use over several weeks is worthwhile. If a product does not work, a different strain can be tried if appropriate — after consulting your GP or pharmacy. There is no guarantee of improvement.
8. Psychotherapy and gut-directed hypnotherapy
Psychotherapeutic methods are among the most effective treatment approaches for IBS — on a par with diet and medication. They are not only intended for people "with psychological problems".¹
Cognitive behavioral therapy (CBT) — best studied
Can help reduce the fear of symptoms and the associated avoidance behavior, as well as improve how stress is handled. There are also online and app-based formats with good evidence.
Gut-directed hypnotherapy
A form of hypnosis developed specifically for IBS. Through targeted relaxation and suggestions, the aim is to modulate the oversensitive gut–brain axis. The effectiveness is proven in controlled studies — also over longer periods. Increasingly available in Germany, but not yet everywhere; coverage by health insurance varies.
Psychodynamic psychotherapy and relaxation methods
Psychodynamic therapy can be effective, especially when stressful life events play a role. Progressive muscle relaxation, yoga or mindfulness methods (e.g. MBSR) can reduce symptoms and can be used well as a supplement.
Psychotherapy for IBS = no statement about it being imagined
It works via a demonstrably disturbed gut–brain axis — that is a real physical system.
9. Living with IBS
Food and symptom diary: A structured diary (meals, symptoms, stress level) can make patterns visible over a few weeks — often more effective than a blanket diet.
Stress: Considered one of the most common triggers. Stress management is usually part of the therapy — schedule regular relaxation firmly.
Exercise: Regular moderate exercise can demonstrably improve IBS symptoms — especially bloating and constipation. Yoga is comparatively well studied for IBS.¹
Travel: Carry medically recommended as-needed medications when travelling. Test new foods carefully. More: Medications when travelling.
Social burden: Many of those affected report shame and withdrawal. An open conversation with people you trust and the exchange in self-help groups (e.g. the German irritable bowel self-help organization) can be a relief.
How brite helps you with irritable bowel syndrome
Recognize triggers, never forget medications, document symptoms — brite supports you in everyday life with IBS.
Health history — document symptoms, diet, bowel movements and triggers day by day and recognize patterns. Track your history
Intake reminder — probiotics, psyllium, peppermint oil, macrogol: brite reminds you reliably of every dose. Set up a reminder
Interaction check — check IBS medications in combination with other active ingredients for free. Check now
Digital medication plan — all medications and supplements clearly organized for your GP and gastroenterology. Go to medication plan
FAQ: Common questions about irritable bowel syndrome
According to current knowledge, IBS is usually not dangerous and mostly does not increase the risk of bowel cancer. The burden of suffering, however, can be considerable and restrict quality of life. Warning signs (e.g. blood in the stool, unintentional weight loss, fever) should in any case be evaluated by a doctor.¹
FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols — short-chain carbohydrates that can cause gas and water influx in the large intestine in sensitive people. A low-FODMAP diet is described in the S3 guideline as an effective option and should be carried out under the guidance of a dietitian.¹
The S3 guideline gives a generally positive recommendation — especially for bloating and abdominal pain. The effect is strain-specific; not every product works for everyone. In practice, a consistent use over several weeks is worthwhile. Prebiotics are mostly not recommended for IBS.¹
Not in the sense of "only psychological". IBS is considered a disorder of gut–brain communication, not something imagined. Stress can amplify the symptoms, and psychotherapy methods (CBT or gut-directed hypnotherapy) demonstrably work — by influencing a real physical axis between the gut and the brain.
Gut-directed hypnotherapy is a form of hypnosis developed specifically for IBS. Through deep relaxation and suggestions, the aim is to calm the oversensitive gut–brain axis. The effectiveness is proven in studies. In Germany, the method is increasingly available.¹
Enteric-coated peppermint oil capsules are positively recommended in the current S3 guideline — especially for cramps and bloating. Tolerability is usually good; many products are available without a prescription.¹
Not necessarily. In younger patients with a typical IBS picture without warning signs, basic diagnostics are often sufficient — stool calprotectin and celiac antibodies are important building blocks here. A colonoscopy is recommended with warning signs, first manifestation at an older age, family history or a lack of response to treatment.¹
Yes — post-infectious IBS affects some people after a pronounced gastrointestinal infection. The risk rises with the severity of the infection. A diarrhea-dominant course often shows itself, which can improve over months to years.¹
The S3 guideline lists stepwise options — from soluble fiber (psyllium) and macrogol to linaclotide or prucalopride for difficult-to-treat cases. In addition, exercise and adequate fluid intake help. Wheat bran is usually rather avoided with a tendency to bloating.¹
Monash University: Low-FODMAP-Diet — Originalforschung und Ernährungsinformationen. monashfodmap.com
Medical disclaimer: This article is for general information and does not replace medical advice, diagnosis or treatment. The choice of medication and dosages are always determined individually by the treating doctor. With warning signs such as blood in the stool, unintentional weight loss, fever or a first manifestation at an older age, a medical evaluation should take place promptly. Irritable bowel syndrome is a real illness — not something imagined. Last updated: April 2026.
