Irritable bowel syndrome (IBS) is a functional bowel disorder — the bowel doesn't work properly, but there are no visible inflammations, ulcers or tissue changes as in Crohn's disease or ulcerative colitis. Standard investigations are usually unremarkable, yet the burden of suffering can still be considerable.
According to the current S3 guideline, irritable bowel syndrome is generally present when three criteria are met: the symptoms have lasted at least three months or recur regularly, they noticeably impair quality of life, and there is no other condition that sufficiently explains the symptoms.¹
IBS is not "all in your head"
According to current knowledge, irritable bowel syndrome is generally not dangerous and usually does not increase the risk of bowel cancer. The suffering is nonetheless real and can considerably limit quality of life.
2. Symptoms and subtypes
Typical main symptoms
Abdominal pain or cramps — often in the lower abdomen, coming in waves; relief 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 emptying, mucus in the stool
Low mood or anxiety — IBS and mental health conditions often occur together
Frequent overlap with functional dyspepsia, fibromyalgia or persistent exhaustion
The four subtypes
IBS-DDiarrhea type
The main features are more frequent, often watery stools, a strong urge to defecate and sometimes a fear of needing the toilet in certain situations. Symptoms are often stronger in the morning and after eating.
IBS-CConstipation type
The main features are hard, infrequent stools and a feeling of incomplete emptying. Bloating is often the dominant accompanying symptom.
IBS-MMixed type
Diarrhea and constipation alternate — sometimes within a few days.
IBS-BBloating type — newly designated in the current guideline
Bloating and a distended abdomen are the main features. Often considered a particularly hard-to-treat subtype.¹
Warning signs — not pure IBS, medical evaluation needed:
Blood in the stool · Unintended weight loss · Fever · Night sweats · Symptom onset at an older age · Family history of bowel cancer or IBD · Anemia. In such situations, a colonoscopy is usually recommended, among other things.
3. Causes: the gut-brain axis
The exact cause of IBS is not fully understood — it is generally an interplay of several factors.¹
Disturbed gut-brain axis: The communication between brain and gut is often oversensitive. The gut sends amplified pain and discomfort signals to the brain (visceral hypersensitivity). Stress can amplify these signals further.
Altered gut motility: Too-fast gut movement → diarrhea; too-slow → constipation. Many people with IBS show uncoordinated gut movements.
Changes in the gut microbiome: An altered composition of gut bacteria (dysbiosis) is discussed as a possible contributing cause — this is where probiotics and the low-FODMAP diet, among others, come in.
Post-infectious IBS: In some people, IBS begins after a gastrointestinal infection. The risk generally 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 "all in your head." The gut-brain axis works in both directions.
Food sensitivities: A sensitivity to FODMAPs, lactose or fructose can intensify 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 other significant conditions have been ruled out.¹
Basic work-up
Blood count, inflammatory markers and thyroid values (TSH)
Fecal calprotectin — an important test to distinguish inflammatory bowel disease
Test for occult blood in the stool (fecal immunochemical test, iFOBT)
If suspected: lactose or fructose breath test
Extended work-up
Colonoscopy — for warning signs, first onset at an older age, family history or a lack of treatment response; 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 rule out endometriosis)
Make a positive diagnosis — don't search for years
A diagnosis of irritable bowel syndrome should be made positively as early as possible — based on the clinical criteria and after ruling out relevant differential diagnoses — not only after years of burdensome testing.
A change in diet is among the most effective approaches in IBS and can in many cases be as effective as medication. The current S3 guideline recommends a low-FODMAP diet particularly for abdominal pain, bloating and diarrhea — usually with support from 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 high-FODMAP foods
For a limited period, high-FODMAP foods are avoided as consistently as possible:
High-FODMAP — 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
Low-FODMAP — usually well tolerated
Rice, quinoa, oats
Potatoes, carrots, zucchini, bell 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 personal tolerance. In practice, many people tolerate some of the groups well.
Phase 3Long-term diet — individual and varied
In the longer term, only the FODMAPs that you personally don't tolerate are restricted. The goal is as varied a diet as possible — permanent strict elimination is generally not recommended, to prevent malnutrition and an impoverishment of the microbiome.
Always do the FODMAP diet with support
The low-FODMAP diet should be carried out with support from a dietitian. Permanent strict elimination without support can lead to malnutrition and is generally not advisable.
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 highly carbonated drinks can intensify symptoms
6. Medications: symptom-oriented
There is no single medication that "cures" irritable bowel syndrome. Drug treatment is generally directed at the symptoms — depending on the dominant pattern of complaints.¹˒²
Cramps and pain
Peppermint oil (enteric-coated capsules) — positively recommended by 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 over the counter.¹
Butylscopolamine
An antispasmodic that can relax the gut muscles. Often used as needed. Available over the counter.
Mebeverine
Acts as an antispasmodic on the gut and generally has fewer anticholinergic side effects than butylscopolamine.
STW 5 (Iberogast)
A herbal combination that can affect several complaints at once. An option for some people — always in consultation with your doctor or pharmacy.
Diarrhea-dominant type (IBS-D)
Loperamide
Slows the passage through the gut. Generally used as needed — not prophylactically over long periods. With frequent use it can cause constipation.
Bile acid sequestrants (e.g. colesevelam)
If bile acid diarrhea is suspected. Given more consideration in the current guideline than in earlier versions.¹
Rifaximin
An antibiotic that acts locally in the gut. An option for hard-to-treat, non-constipated IBS. The decision is usually made by a gastroenterology specialist.
Constipation-dominant type (IBS-C)
Macrogol — recommended by the S3 guideline
An osmotic laxative that binds water in the gut and softens the stool. The current guideline recommends macrogol for IBS-related constipation. Usually well tolerated, even over longer periods.¹
Psyllium husk (psyllium)
Soluble fiber that swells in the gut 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 stools, it can also affect pain and bloating.¹
Prucalopride
A prokinetic medication that can speed up passage through the gut. Mostly used for hard-to-treat chronic constipation.
Bloating
Simeticone/dimeticone — so-called antifoaming agents; effectiveness not clearly proven, but well tolerated. Many products available over the counter.
Peppermint oil and linaclotide (see above) can also have an effect on bloating.
Low-dose antidepressants for hard-to-treat IBS
In hard-to-treat cases, low-dose antidepressants are occasionally used — not primarily because of 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 your treating doctor.¹
The S3 guideline gives a generally positive recommendation for probiotics in IBS — but with important caveats:¹
Not all probiotics work the same — the effect is generally strain-specific
Positive effects described particularly for bloating and abdominal pain
Prebiotics are not recommended in IBS — they may in some cases even worsen bloating
A stool transplant (fecal microbiota transfer) is currently not recommended in IBS outside of studies
Practical tip
If you try a probiotic, it's worth using it consistently for several weeks. If one product doesn't 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 approaches are among the most effective treatments for IBS — on a par with diet and medication. They are not just intended for people "with psychological problems."¹
Cognitive behavioral therapy (CBT) — the best studied
Can help reduce the fear of symptoms and the associated avoidance behavior, and improve how you cope with stress. 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 suggestion, it aims to modulate the oversensitive gut-brain axis. Its effectiveness is demonstrated in controlled studies — also over longer periods. In Germany it is increasingly, but not yet widely, available; coverage by statutory health insurance varies.
Psychodynamic psychotherapy and relaxation techniques
Psychodynamic therapy can be effective, especially when stressful life events play a role. Progressive muscle relaxation, yoga or mindfulness approaches (e.g. MBSR) can reduce symptoms and work well as a complement.
Psychotherapy for IBS = not a statement that it's imaginary
It works via a demonstrably disturbed gut-brain axis — a real physical system.
9. Living with IBS
Food and symptom diary: A structured diary (meals, complaints, 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 generally part of treatment — schedule regular relaxation.
Exercise: Regular moderate exercise has been shown to improve IBS symptoms — especially bloating and constipation. Yoga is comparatively well studied in IBS.¹
Travel: Carry doctor-recommended as-needed medications when traveling. Test new foods cautiously. Learn more: Medication when traveling.
Social burden: Many people report shame and withdrawal. An open conversation with people you trust and exchange in self-help groups (e.g. the German IBS self-help association, Deutsche Reizdarmselbsthilfe) can be a relief.
How brite helps you with irritable bowel syndrome
Spot triggers, never forget your medications, log symptoms — brite supports you in everyday life with IBS.
Health tracking — Record symptoms, diet, bowel movements and triggers day by day and spot patterns. Track your history
Medication reminders — Probiotics, psyllium, peppermint oil, macrogol: brite reliably reminds you of every dose. Set up a reminder
Interaction check — Check IBS medications in combination with other drugs for free. Check now
Digital medication plan — all medications and supplements clearly laid out for your GP and gastroenterology team. Go to medication plan
FAQ: Common questions about irritable bowel syndrome
According to current knowledge, IBS is generally not dangerous and usually does not increase the risk of bowel cancer. The suffering can nonetheless be considerable and limit quality of life. Warning signs (e.g. blood in the stool, unintended weight loss, fever) should always 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 with support from 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, consistent use over several weeks is worthwhile. Prebiotics are usually not recommended in IBS.¹
Not in the sense of "all in your head." IBS is considered a disorder of gut-brain communication, not something imagined. Stress can intensify the symptoms, and psychotherapy approaches (CBT or gut-directed hypnotherapy) work demonstrably — by influencing a real physical axis between gut and brain.
Gut-directed hypnotherapy is a form of hypnosis developed specifically for IBS. Through deep relaxation and suggestion, it aims to calm the oversensitive gut-brain axis. Its effectiveness is demonstrated in studies. In Germany the approach is increasingly available.¹
Enteric-coated peppermint oil capsules are positively recommended in the current S3 guideline — particularly for cramps and bloating. Tolerability is generally good; many products are available over the counter.¹
Not necessarily. In younger patients with a typical IBS picture and no warning signs, a basic work-up is often enough — fecal calprotectin and celiac disease antibodies are important parts of this. A colonoscopy is recommended for warning signs, first onset at an older age, family history or a lack of treatment response.¹
Yes — post-infectious IBS affects some people after a marked gastrointestinal infection. The risk rises with the severity of the infection. A diarrhea-dominant course is common and can improve over months to years.¹
The S3 guideline lists step-by-step options — from soluble fiber (psyllium) and macrogol through to linaclotide or prucalopride in hard-to-treat cases. Exercise and adequate fluid intake help as well. Wheat bran is generally avoided in those prone to bloating.¹
German Society for Gastroenterology, Digestive and Metabolic Diseases (DGVS). dgvs.de
German Medical Association (Bundesärztekammer, BÄK): Patient Information on Irritable Bowel Syndrome. bundesaerztekammer.de
Monash University: Low-FODMAP Diet — original research and dietary information. monashfodmap.com
Medical disclaimer: This article is for general information only and is not a substitute for medical advice, diagnosis or treatment. The choice of medication and dosages are always determined individually by your treating doctor. Warning signs such as blood in the stool, unintended weight loss, fever or a first onset at an older age should be evaluated by a doctor promptly. Irritable bowel syndrome is a real condition — not something imagined. Last updated: April 2026.
