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Irritable Bowel Syndrome

Written by Ada’s Medical Knowledge Team

Updated on

This article contains self-care information for the selected condition. If you have questions or need more comprehensive treatment advice, please consult a medical professional.

What is irritable bowel syndrome?

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder affecting bowel function, characterized by symptoms mostly relating to digestive discomfort, including diarrhea, constipation, bloating, gas, cramping, and abdominal pain. IBS affects around 11 % of the population globally. In Western countries, such as the U.S., women are significantly more likely to be affected by IBS than men, but this ratio varies dramatically worldwide; in India, for example, between 80% and 90% of those affected are male. People with a family history of irritable bowel syndrome are more likely to develop the condition than those without. 1

Different people will experience different combinations of the possible symptoms of irritable bowel syndrome (IBS), thus requiring varying treatments. Diagnosis of IBS will involve identifying triggers of its symptoms, which are usually gastrointestinal and related to a person’s diet and lifestyle so that a person’s exposure to triggers that activate irritable bowel syndrome can be minimized as part of their treatment plan.

IBS can be a long-term condition requiring careful management. The improvement of a person’s digestive health is often brought about by a combination of lifestyle and diet changes designed to reduce bloating, constipation, diarrhea, and other symptoms they may be experiencing. Changes to a person’s diet may involve adopting a low FODMAP diet; a diet low in fermentable short-chain carbohydrates. See IBS and diet. Pharmaceutical interventions may be used to treat chronic (persistent) cases of IBS.

Irritable bowel syndrome does not cause inflammation or permanent damage such as bleeding or ulcers, nor an increased risk of cancers.

Irritable bowel syndrome (IBS) vs. inflammatory bowel disease (IBD)

Both IBS and IBD are conditions which affect the gastrointestinal tract, which is part of the digestive system. Though the symptoms of IBS and IBD can be similar, including abdominal pain, bloating, constipation, diarrhea and abdominal cramping, IBD is a more serious condition.

Inflammatory bowel diseases are a group of conditions in which the body’s own immune system attacks parts of the digestive system in the gastrointestinal tract. This group includes chronic diseases such as ulcerative colitis, which affects the large intestine, and Crohn’s disease, which can affect the entire digestive tract, damaging both the surface and the deep tissues of the intestines. 2

In contrast, irritable bowel syndrome (IBS) only affects the function and behavior of the intestines. IBS is not an autoimmune condition. Although IBD does not cause IBS, those affected by IBD have a greater likelihood of developing IBS than the general population. In contrast, having IBS does not impact a person’s likelihood of developing IBD. 2

Irritable bowel syndrome (IBS) symptoms

Different kinds of IBS are diagnosed according to their symptoms, with people experiencing different combinations of the symptoms of irritable bowel syndrome, including bloating, diarrhea, constipation and painful abdominal cramps.

People with IBS may suffer from diarrhea or constipation or both, either at the same time or at alternating times. 3

Common symptoms include:

1. Abdominal pain and cramping

Abdominal pain and cramping, particularly felt in the lower belly, is one of the most common symptoms of IBS. Abdominal cramps can be caused by constipation or diarrhea, other symptoms of irritable bowel syndrome. They typically increase after meals. For some people affected by IBS, having a bowel movement (BM) can intensify pain and cramping; for others, having a BM can reduce these symptoms.

2. Irritable bowel syndrome (IBS) with predominant diarrhea

Some people experience diarrhea as a main symptom of irritable bowel syndrome, passing loose, watery stools more than three times per day. In people with IBS, diarrhea may occur suddenly, particularly after encountering triggers of their symptoms. In cases of irritable bowel syndrome in which a person experiences diarrhea as one of their most prominent symptoms, the condition is sometimes called IBS-D. Altering a person’s diet is the first-line treatment for IBS-D, followed by prescribing medications. 4

3. Irritable bowel syndrome (IBS) with predominant constipation

Those experiencing constipation as a symptom of IBS may pass fewer than threebowel movements per week. When it is passed, stool is often small and hard. When a person experiences constipation as one of the principal symptoms of their irritable bowel syndrome, this is sometimes called IBS-C. 5

Good to know: IBS-C shares many symptoms ‒ including bloating, abdominal pain and infrequent, difficult bowel movements ‒ with another common gastrointestinal disorder, chronic idiopathic constipation (CIC). Current research suggests that that IBS-C and CIC are different conditions, despite their significantly overlapping symptoms. If a person seeks medical attention for constipation, doctors will ensure that appropriate testing is undertaken so that a differential diagnosis can be made, as these conditions require different treatment approaches to relieve constipation.

4. Irritable bowel syndrome (IBS) with constipation and diarrhea

When a person is equally affected by constipation and diarrhea as symptoms of irritable bowel syndrome, this is called IBS-M (mixed irritable bowel syndrome) or IBS-A (alternating irritable bowel syndrome.

5. Rectal tenesmus

Rectal tenesmus involves cramping and spasms in the rectum. This leads to feeling that a bowel movement is incomplete, even if the bowel has actually been evacuated successfully. This feeling may lead to abdominal pain and cramping, associated with straining to bring about a bowel movement.

Good to know: Tenesmus is a symptom of many other gastrointestinal conditions, as well as a symptom of IBS. If a person seeks medical attention for rectal tenesmus, doctors will check for inflammation of the colon, to rule out a diagnosis such as ulcerative colitis (a form of IBD) or colon cancer.

6. Bloating and gas

Many people with IBS experience intense bloating (a sensation of increased abdominal pressure). This may or may not be due to an increased quantity of gas in the gastrointestinal tract; about 50 % of people experience increased abdominal pressure without a buildup of gas. 6

Some people with irritable bowel syndrome also experience increased burping.

7. Mucus in stool

Passing mucus in the stool is a common symptom of IBS, but passing blood may indicate a more serious condition affecting the bowel, colon or gastrointestinal tract. Always seek medical attention for a prompt diagnosis if blood is present in bowel movements.

People experiencing any possible symptoms of IBS can use the free Ada app to carry out a symptom assessment.

Causes of irritable bowel syndrome (IBS)

Despite ongoing research to determine definitive causes of IBS, these are still unclear. Contributing factors may include infection, neurohormonal factors, food sensitivities and bacterial overgrowth. An individual’s psychological condition, hormone changes or stress levels are other possible causes.


It has been observed that some patients experience their first IBS symptoms after acute infectious enteritis. This so-called postinfectious IBS may be caused by viral, bacterial, protozoan or helminth infection. Several research studies have shown that IBS symptoms can increase after infectious enteritis, but the actual cause of these symptoms requires further research.

Neurohormonal factors

Some people experience visceral hypersensitivity, which is a greater sensitivity to pain from the organs, including the stretching of the bowel as gas or stool passes through it. This may be linked to IBS symptoms, including abdominal pain, urgent bowel movements, and bloating. However, the cause of this hypersensitivity is unknown. 7 It is also possible that the brain of a person with IBS processes pain differently than that of an unaffected person or that other differences in the signals passed between the brain and the intestinal tract are related to IBS. 8

Neurotransmitters or reproductive hormones may be imbalanced in some people with IBS, and these may be affected by changes to an individual’s hormones, such as throughout the menstrual cycle. The possible role of sexual hormones in IBS may be supported by the fact that roughly twice as many women as men are affected in some countries. 9

Food sensitivities

It has been observed that an individual with IBS may experience symptoms more often due to an intolerance of foods such as wheat; dairy products; fatty, creamy or fried foods; alliums such as garlic or onions; stone fruits and other kinds of fruit; brassicae such as cabbage, cauliflower or Brussels sprouts; pulses such as lentils or beans and chili peppers.

Eliminating certain foods from the diet has been shown by some dietary studies to relieve the symptoms of IBS, but these foods vary according to the individual. More research on food sensitivities and their effect on IBS is required.


Small intestine bacterial overgrowth (SIBO) is when too many of the gut’s naturally occurring bacteria accumulate in the small intestine. Some research has linked SIBO to IBS, and that antibiotic treatment has decreased IBS symptoms in some people with SIBO. 10 It is not clear from this research whether antibiotics affect the SIBO directly or affect the IBS in a different manner.

Malabsorption of fructose

In some people, IBS symptoms can be caused by the digestive system failing to absorb fructose effectively. Fructose is a kind of sugar found in fruits and some vegetables, and is often used as an artificial sweetener in processed foods. When fructose is not absorbed properly by the digestive system, it can ferment in the colon (large intestine). This can result in gastrointestinal symptoms such as gas, bloating and diarrhea.

For people whose IBS is believed to result from malabsorption of fructose, eating foods which are low in fructose may be helpful in reducing their symptoms. See this resource from the University of Virginia’s Digestive Health Centre for more information on low-fructose foods.

Additional factors

IBS is often linked to psychological factors such as stress, anxiety or depression, and stress management is one possible treatment tool. Genetics may play a role in the development of IBS, but there is limited evidence to support this.

Irritable bowel syndrome (IBS) diagnosis

A diagnosis of IBS is usually made by considering recurrence of symptoms over a period of 3 to 6 months rather than solely through a physical examination or by visual inspection of the bowel during colonoscopy. To assist doctors in making a diagnosis, a person may keep a diary of their diet and gastrointestinal symptoms during this period to identify factors that may be triggering their possible IBS.

Although it does not form the sole basis of a diagnosis of IBS, a colonoscopy may still be performed as part of an IBS diagnosis to help rule out other issues. This is an imaging procedure in which the colon or large intestine is visualized by inserting a thin, flexible tube containing a camera into the body through the rectum. See this resource on preparing for a colonoscopy for more information.

Other possible measures which may be used in making a potential diagnosis of irritable bowel syndrome include a blood or stool test, flexible sigmoidoscopy or a barium series. 11

People experiencing possible symptoms of IBS can also use the free Ada app to carry out a symptom assessment.

Irritable bowel syndrome treatment

Treatments for IBS include:

Lifestyle changes

Lifestyle changes addressing diet or stress are usually the first approach to IBS treatment.

Stress and anxiety treatments

Addressing generalized stress and anxiety is a common treatment approach. Some people experience anxiety around their IBS symptoms (known as GI symptom-specific anxiety), and may limit their exposure to activities and situations that would be affected by their IBS. This can increase their anxiety, creating a vicious cycle that increases their symptoms. Therapies like cognitive behavioral therapy, psychotherapy, relaxation therapy, biofeedback, and hypnotherapy may be used to help individuals both manage general stress and break this cycle. Self-care to manage stress is another option, with common techniques including meditation, yoga and exercise.

IBS and diet

Each person has different dietary triggers for IBS. If sensitivity to specific foods is a trigger for IBS symptoms, treatment may include reducing or eliminating these foods from the diet. Many people find it helpful to avoid high-FODMAP foods; FODMAP stands for: Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols; fermentable short-chain carbohydrates which are prevalent in a regular diet, which the small intestine does not absorb very well. 12

Examples of low FODMAP foods which may ease symptoms of irritable bowel syndrome when included in a person’s diet include: 12

  • Lactose-free or low-lactose dairy products, such as non-dairy milks, hard cheeses such as cheddar
  • Low-fructose fruits such as oranges, kiwis and strawberries
  • Low-fructan vegetables such as bean sprouts, carrots, eggplant, potatoes, olives, turnips
  • Protein such as lean meat and tofu
  • Gluten-free grains

Examples of high FODMAP foods, which may aggravate symptoms of irritable bowel syndrome, and should be excluded from one’s diet where possible, include: 12

  • Lactose - cow’s milk, yogurt, and cream
  • Fructose - fruits and products high in natural sugars from fruit, such as apples, pears, peaches, corn syrup
  • Fructans - vegetables and grains high in fructans include artichokes, garlic, onions, broccoli, beetroot, and grains such as wheat and rye
  • Polyols - sweeteners such as sorbitol and xylitol, found in sugar-free products

Another approach to alleviating symptoms of irritable bowel syndrome by changing one’s diet is to eat smaller, more frequent meals. Eating more slowly can reduce gas and bloating. Along with an individual’s possible food intolerances, foods commonly associated with abdominal cramping or diarrhea include coffee, caffeine, alcohol or high-fat foods, as well as poorly-digested sugars, such as sorbitol or fructose. Beans, raisins, or bread can cause gas, and lactose intolerance can trigger IBS symptoms. Eating a high-fiber diet can improve stool quality and keep the GI tract healthy, but a diet excessively high in fiber can also cause gas and diarrhea.

Irritable bowel syndrome medications

Medications are available to treat moderate to severe IBS. These include:

Anti-diarrheal medications

If diarrhea is present with IBS, over-the-counter anti-diarrhea medications like loperamide (Imodium) are often used. Common prescriptions drugs used to treat it include diphenoxylate (Lomotil, Lomocot) and atropine.

Anticholinergic and antispasmodic medications

Antispasmodic medications such as dicyclomine (Bentyl) and hyoscyamine (Levsin), as well asanticholinergic medications, are commonly prescribed to decrease painful abdominal spasms. Smooth muscle relaxants, such as alverine, mebeverine and peppermint oil may also be used.

Antidepressant medications

People affected by IBS who also have depression may be prescribed selective serotonin reuptakeinhibitors (SSRIs), such as fluoxetine (Prozac, Sarafem) or paroxetine (Paxil), as well astricyclic antidepressants, such as nortriptyline (Pamelor), imipramine (Tofranil) ordesipramine (Norpramin). People with IBS who do not experience depression may be also prescribed antidepressants due to their effect on the connection between the brain and gut.

Probiotics and antibiotics

An imbalance in the normal bacteria (gut flora) living in the human gut can affect its function and overall wellness, and probiotic supplements can introduce healthy, normal bacteria. More research is needed to prove their overall effectiveness, but some IBS sufferers do gain relief from probiotic supplements, with Bifidobacteriuminfantis the most commonly studied probiotic.

Some IBS may be associated with overgrowth or infection of harmful bacteria in the gut, and antibiotic medications that reduce bacteria are a possible treatment. The antibiotic Xifaxan (Rifaximin) may be used to treat this kind of IBS.

Other names for irritable bowel syndrome

  • Spastic colon

Irritable bowel syndrome FAQs

Q: Is it IBS, IBD, Crohn’s disease or ulcerative colitis?
A: IBS is often confused with IBD. While symptoms may be similar, IBD causes inflammatory damage to the intestines, but IBS does not. People with IBS who pass bloody stool, lose weight or experience extreme cramping should go to a doctor to be evaluated for IBD or another serious condition.

Q: Can IBS cause cancer? Is IBS fatal?
A: IBS does not increase the risk of colon or other cancers, and it's not fatal.

Q: Can IBS be cured?
A: As symptoms of IBS and their treatments vary from person to person, there's no single cure for IBS. However, individuals can manage their symptoms to minimize their effects on daily life and activities, sometimes ending their symptoms entirely.

Q: Is medication necessary for IBS?
A: Many cases of IBS can be controlled through lifestyle and dietary changes, under a doctor’s advice.