Irritable Bowel Syndrome

What is irritable bowel syndrome?

Irritable bowel syndrome (IBS) is a disorder affecting bowel function, characterized by symptoms including diarrhea, constipation, gas, cramping and abdominal pain. Different people, though, will experience different clusters of symptoms, thus requiring varying treatments. IBS can be a long-term condition requiring careful management, and it is often addressed with a combination of lifestyle and dietary changes, as well as pharmaceutical interventions in chronic cases. IBS does not cause inflammation or permanent damage such as bleeding or ulcers, nor an increased risk of cancers.

IBS vs. inflammatory bowel disease (IBD)

Though their symptoms can be similar, IBD is a more serious condition. IBD 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.

Irritable bowel syndrome symptoms

Different kinds of IBS are diagnosed according to their symptoms, with people experiencing different combinations of diarrhea, constipation and painful abdominal cramps. Common symptoms include:[1]

Abdominal pain

Abdominal cramping, particularly felt in the lower belly, is one of the most common symptoms of IBS. These cramps typically increase after meals, and are relieved by a bowel movement.

Diarrhea and constipation

Some people experience diarrhea as a main symptom of IBS, passing loose, watery stools more than three times per day. Those experiencing constipation as a symptom of IBS may pass fewer than three bowel movements per week. When it is passed, stool is often small and hard. Diarrhea and constipation may occur on their own or in alternating periods.

Feeling that a bowel movement is incomplete

Bloating and gas

Many people with IBS experience intense bloating and gas, and some experience increased burping.

Mucus in stool

Passing mucus in the stool is a common symptom of IBS, but passing blood may indicate a more serious condition.

Causes of 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.[2] 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.[3]

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 is supported by the fact that roughly twice as many women as men are affected.[4]

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; alums 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.[5] It is not clear from this research whether antibiotics affect the SIBO directly, or affect the IBS in a different manner.

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 diagnosis

IBS is diagnosed by considering recurrence of symptoms over a period of three to six months, rather than solely through physical examination or by visual inspection of the bowel during colonoscopy. A colonoscopy, though, may still be performed as part of an IBS diagnosis to help rule out other issues. Other possible diagnostic tools include a blood or stool test, flexible sigmoidoscopy or a barium series.[6]

Irritable bowel syndrome treatments

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. Another approach 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 breads 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.

Anti-diarrheal medications

Over the counter anti-diarrheal medications like loperamide (Imodium) are often used to treat IBS. Common prescriptions drugs include diphenoxylate (Lomotil, Lomocot) and atropine.

Anticholinergic and antispasmodic medications

Antispasmodic medications such as dicyclomine (Bentyl) and hyoscyamine (Levsin), as well as anticholinergic 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 reuptake inhibitors (SSRIs), such as fluoxetine (Prozac, Sarafem) or paroxetine (Paxil), as well as tricyclic antidepressants, such as nortriptyline (Pamelor), imipramine (Tofranil) or desipramine (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 the use of probiotic supplements, with Bifidobacterium infantis the most commonly studied probiotic.

Some IBS may be associated with an 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.

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 risk of colon or other cancers, and it is not fatal.

Q: Can IBS be cured?
A: As symptoms of IBS and their treatments vary from person to person, there is 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.

Other names for irritable bowel syndrome

  • Spastic colon

  1. Irritable Bowel Syndrome.” National Institute of Diabetes and Digestive and Kidney Diseases. Accessed: September 15, 2017

  2. Irritable Bowel Syndrome (IBS).” National Institute of Diabetes and Digestive and Kidney Diseases. Accessed: September 15, 2017

  3. Irritable Bowel Syndrome.” National Institute of Diabetes and Digestive and Kidney Diseases. Accessed: September 15, 2017

  4. Irritable Bowel Syndrome.” National Institute of Diabetes and Digestive and Kidney Diseases. Accessed: September 15, 2017

  5. Irritable bowel syndrome clearly linked to gut bacteria.” Science Daily. Accessed: September 15, 2017

  6. Irritable Bowel Syndrome (IBS).” National Institute of Diabetes and Digestive and Kidney Diseases. Accessed: September 15, 2017