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More Information on Irritable Bowel Syndrome (IBS)


This information is intended only to provide general guidance. It does not provide definitive medical advice. It is important that you consult your doctor about your specific condition.

What is irritable bowel syndrome?

Irritable bowel syndrome (IBS) is a condition in which the intestine does not function normally. Patients with irritable bowel syndrome (IBS) have abdominal pain, cramping, and/or bloating, usually associated with a change in bowel movements (diarrhea, constipation, or both). The discomfort may be relieved by moving the bowels. Other common symptoms include a sensation of incomplete evacuation of stools and mucus in the stools. The symptoms typically have been present for several months or longer, although not necessarily every day. There is no other disease or injury that could be causing the pain or bowel symptoms. Other names for irritable bowel syndrome (IBS) include spastic colon and mucus colitis. There are several subtypes of irritable bowel syndrome based on the consistency of the stool:

  1. constipation-predominant irritable bowel syndrome;
  2. diarrhea-predominant irritable bowel syndrome; and
  3. mixed irritable bowel syndrome, in which both diarrhea and constipation occur frequently at different times.

What causes irritable bowel syndrome?

Irritable bowel syndrome (IBS) is due to a combination of abnormal processes that together cause the symptoms. These abnormalities may be physical, psychological, or dietary:

Abnormal muscular coordination (motility) of the intestine

Food, fluid, and stool are propelled through the intestine by peristalsis, muscular contractions sweeping down the intestine. Slow motility can cause constipation or bloating, and overly fast motility can cause diarrhea. Spasms of the muscles can cause pain or other symptoms. Some irritable bowel syndrome (IBS) patients have overly reactive intestinal motility, in which the muscular activity is dramatically increased by stress or eating.

Brain-gut communication problems

The brain and gut (intestines) communicate by nerves, with sensations from the intestine reaching the brain and signals from the brain affecting the intestine. Problems with this brain- gut communication can contribute to irritable bowel syndrome (IBS) symptoms.

Abnormal pain sensation

Irritable bowel syndrome (IBS) patients have a lower pain threshold in the intestine. The intestine is overly sensitive, so it takes a smaller amount of stretching of the bowel by gas or food to cause pain or an urge to have a bowel movement, compared to people without irritable bowel syndrome (IBS). The brain may process sensations and pain signals from the intestine differently in people with irritable bowel syndrome (IBS). Sensations that would not even be noticed by normal individuals may be interpreted as pain or urgency by the brain in patients with irritable bowel syndrome (IBS).

Psychological problems and stress

Psychological problems, such as anxiety, panic disorder, depression, and post-traumatic stress disorder, are frequently found in irritable bowel syndrome (IBS) patients. Other irritable bowel syndrome (IBS) patients have no psychological problems. Stress worsens digestive symptoms and certainly can contribute to irritable bowel syndrome (IBS). Lack of sleep can contribute to irritable bowel syndrome. People who have suffered past physical or sexual abuse are particularly prone to develop irritable bowel syndrome.

Food sensitivity

Irritable bowel syndrome (IBS) symptoms may be triggered by foods rich in carbohydrates, fats, or spices, or by alcohol. Some patients cannot digest or absorb particular types of food, such as lactose (in dairy products), fructose (in certain fruits and syrups), or gluten (in wheat). A lack of fiber in the diet may contribute to irritable bowel syndrome (IBS).


There are hundreds of species of bacteria, numbering in the thousands, normally living in the human colon (large intestine). If some species of bacteria become more predominant, they can cause digestive symptoms. This can occur after use of antibiotics, certain illnesses, or alterations in intestinal motility. A more favorable balance of bacteria in the colon can be achieved by taking probiotics, which are capsules or other preparations of "good" bacteria. However, the quality and specific contents vary greatly among different brands of probiotics. Your doctor can help you choose the proper probiotic.

Small intestinal bacterial overgrowth (SIBO)

Normally, there are very few bacteria living in the small intestine (in contrast to the huge numbers in the large intestine). Small intestinal bacterial overgrowth (SIBO) is an abnormally high number of bacteria in the small intestine. This can cause gas, bloating, diarrhea, weight loss, and nutritional deficiencies. Some researchers believe that small intestinal bacterial overgrowth (SIBO) can cause irritable bowel syndrome (IBS) in some patients, and certain antibiotics can sometimes help irritable bowel syndrome (IBS).

Acute gastroenteritis

Some people who have bacterial or viral gastroenteritis -- a short-lived infection of the stomach and intestines with severe vomiting and/or diarrhea -- may later develop irritable bowel syndrome (IBS). This is called post-infectious irritable bowel syndrome (IBS). It is not known why this happens in some people and not others. Subtle inflammation of the lining or nerves of the intestine or psychological factors may be involved.

Genetics and irritable bowel syndrome

There is probably some contribution of genetics that makes certain people more prone to develop irritable bowel syndrome (IBS). Irritable bowel syndrome (IBS) is more common in people who have relatives with a history of digestive problems, but this could also be due to the home environment, dietary preferences, or a heightened awareness of gastrointestinal symptoms.

Who gets irritable bowel syndrome?

Irritable bowel syndrome (IBS) is common, occurring in 10-15% of people. It is more common in women and usually begins before the age of 30.

How is irritable bowel syndrome diagnosed?

Dr. Harary will take a complete medical history and physical examination. He will ask questions about the exact location, timing, and frequency of your pain and bowel movements, any other symptoms, family history of digestive symptoms, recent infections, medications, and triggering or associated events. You should be prepared to answer these questions when you see Dr. Harary . In order to diagnose irritable bowel syndrome (IBS), symptoms must have been present for at least several months and occur 3 times per month. It may be necessary to exclude other diseases that can mimic irritable bowel syndrome (IBS). Further testing may or may not be needed, and may include blood tests, stool tests, breath tests, X-rays or ultrasound, and colonoscopy.

Additional testing is particularly helpful when there is:

- fever - symptoms beginning after age 40

- rectal bleeding - failure to improve

- weight loss - very frequent diarrhea

- family history of colon cancer - exposure to antibiotics

- family history of colitis or Crohn’s disease - circumstances suggesting an infection

- family history of celiac disease - anemia 

The response to dietary changes or medications can help confirm the diagnosis of irritable bowel syndrome (IBS). Occasionally it may be helpful to keep a food diary to identify the offending foods. Skin or blood tests for allergy are usually not helpful.

How is irritable bowel syndrome treated?

Dr. Harary treats irritable bowel syndrome (IBS) with dietary modifications, medication, stress reduction, probiotics, and/or psychological treatments. Although a single treatment can sometimes be sufficient, many patients require a combination of approaches, which often requires patience and persistence until the right mix of approaches is found.

Dietary modifications for irritable bowel syndrome

Irritable bowel syndrome (IBS) can sometimes be helped by avoiding very large meals and following a healthy, balanced diet low in junk food, fats, and sodas, and high in fiber and complex carbohydrates (whole grain pasta or bread, cereals, brown rice, nuts, fruits, and vegetables).

In some people, irritable bowel syndrome (IBS) symptoms are worsened or caused by certain foods such as:

- dairy products.

- alcohol or caffeine drinks.

- artificial sweeteners such as sorbitol or xylitol (especially in diet gum or candies).

- wheat (gluten) (but you should not go on a wheat free diet before being tested for celiac disease by your doctor).

- beans, cabbage, soy milk, tofu, peas, and lentils, which may cause gas.

- fructose (present in high amounts in apples, pears, dried fruit, fruit juice, honey, and processed foods with high fructose corn syrup).

Dr. Harary often treats irritable bowel syndrome by using elimination diets, in which one or more of the above types of food are decreased or eliminated from the diet. You should not go on a gluten-free diet without first being tested for celiac disease by your doctor. Another diet treatment is the FODMAP diet, which sometimes helps patients with bloating, gas, abdominal pain, or diarrhea. FODMAP stands for fermentable, oligosaccharides, disaccharides, monosaccharides, and polyols, This is a difficult diet in which a wide variety of plant-based foods are eliminated or decreased. It should only be used with the guidance of a physician or nutritionist.

In constipated patients, increasing dietary fiber can be very helpful. Fiber is present in round, hard fruits such as apples, pears, peaches, and plums, legumes (beans, etc.), carrots, cauliflower, Brussels sprouts, nuts, cereals with high fiber (look for 5 grams or more of fiber listed on the box), whole wheat bread, and brown rice. Lettuce, tomatoes, cucumbers, citrus fruits, and melons do not contain much fiber, although they have other health benefits. Fiber intake should be increased gradually to reduce the risk of causing gas and bloating. Fiber supplements, such as Metamucil, Citrucel, Benefiber, FiberCon, and other brands can be helpful for constipation when dietary fiber alone is not helping.

Medications for irritable bowel syndrome

Fiber supplements (Metamucil, Citrucel, Benefiber, FiberCon, and other brands).

Laxatives for constipation: Polyethylene glycol (MiraLax, other brands), and magnesium preparations are available over-the-counter. Prescription laxatives include lactulose, sorbitol, Linzess (linaclotide), and Amitiza (lubiprostone). Linzess may also have a direct effect on pain sensation in the intestine.

Anti-spasmodics (such as hyoscyamine, dicyclomine, methscopolamine, and Donnatal) relax the muscle of the intestine and can help intestinal muscle spasms or abdominal pain.

Antidepressants in low doses can reduce sensitivity to pain and may also normalize intestinal motility and production of fluids.

Loperamide (Imodium) and diphenoxylate (Lomotil) are anti-diarrheal medications.

Antibiotics, such as rifaximin and others, may help selected patients with small intestinal bacterial overgrowth (SIBO). Antibiotics should not be used routinely to treat irritable bowel syndrome (IBS)

Alosetron (Lotronex) is a medication used specifically for diarrhea-predominant irritable bowel syndrome (IBS). It must be prescribed with special restrictions.

Probiotics for irritable bowel syndrome

Probiotics are live microorganisms, usually bacteria, that are similar to some microorganisms normally found in the colon. When taken in large enough amounts, probiotics may improve irritable bowel syndrome (IBS) symptoms. However, our knowledge of which bacteria are best and went to use them is limited, and more scientific research is needed. Probiotics are available in capsule, pill, and powder form, and are included in some foods such as yogurt. Commercially available probiotics vary greatly in their specific microorganisms, the quantity of bacteria, and the quality of the product. Your doctor can advise you as to the specific probiotics you should be using for irritable bowel syndrome (IBS). You can read more at

Psychological therapies for irritable bowel syndrome

The following approaches address psychological problems that contribute to the symptoms of irritable bowel syndrome (IBS):

Cognitive behavioral therapy focuses on thoughts and actions.

Psychodynamic therapy focuses on emotions and past events.

Hypnosis therapy

Mindfulness training teaches people to focus their attention on sensations occurring at the moment and to avoid worrying about the meaning and consequences of these sensations.

Relaxation techniques, such as meditation and yoga.

Minimizing stressful life situations.

Regular exercise and getting enough sleep. 

To learn more about irritable bowel syndrome treatment and diagnosis offered by Dr. Harary, please contact our New York City office. 


Albert M. Harary, MD
110 East 55th Street, 17th Floor
Midtown East/Upper East Side

New York, NY 10022
Phone: 212-702-0123
Fax: 212-355-4244

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