Irritable Bowel Syndrome (IBS)

Published: August 3, 2017

When a person’s large intestine doesn’t function normally, and there is no evidence that a disease caused it, it’s considered to be irritable bowel syndrome (IBS). IBS is a chronic (ongoing) problem of the large intestine. It’s not a disease. It’s a group of symptoms that occur together.

About 10 to 15 percent of American adults have IBS. It affects twice as many women as men, and is more common in people under the age of 45. But IBS is rarely diagnosed. Only 5 to 7 percent of adults have received an IBS diagnosis. Many people who have IBS are embarrassed by the condition, and there is a common perception that nothing can be done for it. That’s why so many women who have IBS never talk about it with their doctor. It’s true that IBS has no cure, but there are effective ways to treat the condition.

People who have IBS often have other conditions related to their gastrointestinal (GI) tract. It’s common for people with IBS to have gastroesophageal reflux disease (GERD) and dyspepsia, for example. They are also more likely to get conditions that aren’t related to the GI tract, such as chronic fatigue syndrome, depression, anxiety, temporomandibular joint (TMJ) disorders, chronic pelvic pain, and other conditions.

The Types of IBS

Doctors identify IBS as one of four types:

  • IBS with constipation (IBS-C): People with this type of IBS have hard or lumpy stools at least 25 percent of the time, and loose or watery stools less than 25 percent of the time.
  • IBS with diarrhea (IBS-D): This type of IBS is the reverse of IBS-C. People with this type have loose or watery stools at least 25 percent of the time, and hard or lumpy stools less than 25 percent of the time.
  • Mixed IBS (IBS-M): As the name implies, this is a combination of IBS-C and IBS-D. Patients with IBS-M have hard or lumpy stools at least 25 percent of the time and loose or watery stools at least 25 percent of the time, as well.
  • Unsubtyped IBS (IBS-U): In this type of IBS, people have hard or lumpy stools less than 25 percent of the time and loose or watery stools less than 25 percent of the time.

Causes and Triggers

What causes IBS? The exact cause is unknown. But we do know that certain things can trigger IBS symptoms in people who already have it. These are some of the key factors that can trigger IBS or make it worse:

  • Brain-gut signal problems: Your brain and the nerves in your gut signal each other to control the functions of the GI tract. When something goes wrong in these signals, IBS symptoms can occur.
  • Problems with how food moves through the colon: If food moves slowly through your colon, it can trigger constipation. If it moves quickly, it can trigger diarrhea. There can be other problems, too, such as spasms or an increase in how often your bowel contracts when you feel stress or after you have eaten.
  • Food sensitivity or allergy: It’s common for people with IBS to notice symptoms after eating foods that “don’t agree” with them. These can include foods that have lots of carbohydrates, are spicy or fatty. Coffee and alcohol can also trigger symptoms.
  • Stress: This can make a lot of health conditions worse, and IBS is no exception. Stress can cause muscles to cramp, which can affect the symptoms of IBS.
  • Mental health issues: Depression, anxiety, panic disorder, and post-traumatic stress disorder are among the conditions linked to IBS. The exact reason for the link is unclear. Even slight stress can trigger IBS symptoms.
  • Infection in the stomach or intestines: Bacterial infections in the GI tract can trigger IBS symptoms. Experts aren’t sure why GI tract infections trigger IBS in some people. Abnormalities in the lining of the GI tract may play a role.
  • Too much intestinal bacteria: You have bacteria in your stomach when you’re in normal health, but too much can trigger IBS symptoms. Among the symptoms of bacterial overgrowth are excess gas or diarrhea. This overgrowth can be caused by antibiotic use.
  • Changes in hormones or other body chemicals: Any changes in the body’s chemistry can trigger IBS symptoms.
  • Genetics: It’s not clear that IBS has a genetic source. But research shows it’s more common in people who have family members with a history of GI tract problems.

Recognizing the Symptoms of IBS

Healthy bowels result in regular stools that are solid (neither too loose nor too firm) and well formed. Having a bowel movement should cause no pain and no straining should be necessary.

With IBS, that isn’t the case. IBS is different for each person. Some experience relatively mild symptoms, while others have severe symptoms that interfere with their everyday lives.

IBS signs and symptoms include:

  • Abdominal cramps and pain
  • Changes in stool appearance
  • Diarrhea
  • Constipation
  • Alternating diarrhea and constipation
  • Intestinal gas
  • Abdominal bloating

To be considered as IBS, any of these symptoms must have started at least 6 months ago. They also must have appeared three times over the past 3 months.

Diagnosing IBS

There is no single test that lets your doctor know you have IBS. Instead, your doctor relies on your signs and symptoms, and how they measure up to what are called the Rome IV criteria.

The Rome IV criteria emphasize the onset and pattern of your pain and discomfort, and then define the subtype of IBS based on your symptoms. It’s a very good idea to keep a written record of your symptoms, as this will help your doctor make an accurate diagnosis. That’s the key to treating IBS.

Your doctor will conduct a complete medical history. This will include questions about your symptoms, your family’s history of GI problems, any recent infections you’ve had, the medicines you take, and any stressful events that might be connected to the start of your symptoms. He or she will also perform a complete physical exam of you. Along with your reported symptoms, these are the basics of an IBS diagnosis.

Tests are typically not needed for an IBS diagnosis, but they are sometimes ordered by doctors to rule out other possible causes. These include:

  • Blood test: This can rule out other possible causes for your symptoms.
  • Stool test: Your doctor will give you a container for catching and holding a stool sample, along with instructions on where to take or send the kit. Lab analysis of the kit will look for blood or parasites.
  • Flexible sigmoidoscopy: A sigmoidoscope is a flexible narrow tube with a camera and a light on one end for looking inside your rectum and lower colon. It can detect problems in the lower GI tract. Your doctor may take a biopsy during this procedure.
  • Colonoscopy: In this procedure, a long, flexible narrow tube with a light and tiny camera on one end examines your rectum and colon. The images it creates can spot problems.
  • Lower GI series (barium enema): This procedure uses x-rays to explore your large intestine. You lie on a table while a tube is inserted into your anus. The tube carries barium into your large intestine.

Living and Coping with IBS

IBS has no cure, but it can be managed effectively. Making changes to your diet is typically an important part of keeping IBS at bay.

One way to combat IBS is to keep a food diary that lists what you eat at each meal and which foods, if any, triggered your symptoms. It should note when you ate, what you ate, the IBS symptoms that occurred, and when they occurred. A food diary can be an important reference for your doctor and you in determining how to treat and live with IBS.

People with IBS should generally avoid:

  • Foods high in fat
  • Spicy foods
  • Some dairy products
  • Carbonated drinks
  • Any drink that contains alcohol or caffeine
  • Any drink with a large amount of artificial sweeteners
  • Chocolate
  • Some fruits
  • Beans, cabbage, and other foods that may trigger gas

It’s just as important to know what you can eat if you have IBS. In general, you want to eat foods that are rich in fiber and are low in fat and high in carbohydrates, including:

  • Rice
  • Whole-grain breads and cereals
  • Some fruits
  • Vegetables (except those that cause gas in you)

Fiber is another dietary element that can help with IBS symptoms, especially constipation. However, it can be a mixed blessing. Too much fiber at once can trigger gas, which can in turn trigger symptoms. It’s a good idea to add fiber gradually to your diet in order to prevent gas and bloating.

People with IBS should also drink plenty of water and eat smaller meals more often during the day, so that they’ll be easier to digest.

Exercise also plays an important role in managing IBS symptoms. There are many benefits to getting and staying physically active: It alleviates stress and the symptoms of depression and anxiety; it helps stimulate your intestines to contract as they should; and it helps you feel better in general about yourself. The general guidelines for exercise are to try and get at least 30 minutes of moderate-intensity physical activity most days of the week. If you haven’t been active, talk with your doctor about what exercise would work best for you, and how much to get.

Keeping stress at bay is another good approach to controlling IBS symptoms. Too much stress can trigger IBS symptoms and is generally bad for your health. You can manage stress by:

  • Practicing meditation, tai chi, or yoga
  • Enjoying a favorite hobby, or taking on a new one
  • Reading a book or magazine
  • Taking a long bath
  • Breathing deeply
  • Seeking counseling and support, either in an individual or group setting
  • Avoiding or reducing stressful situations as much as possible
  • Getting enough sleep

Treating IBS

Your doctor may prescribe drugs to help relieve the symptoms of IBS. Some of the most commonly prescribed are:

  • Fiber supplements: If increasing fiber in your diet doesn’t help control your symptoms, your doctor may recommend a fiber supplement.
  • Laxatives: Although they work in different ways, laxatives can help with constipation. Your doctor may recommend one that’s right for your symptoms.
  • Antidiarrheal medicines: For people with IBS-D, a drug such as loperamide may help slow the movement of stool through your colon. Although effective in reducing diarrhea, these medicines do not help with pain, bloating, or other symptoms.
  • Antispasmodics: Drugs such as hyoscine, cimetropium, and pinaverium can help control muscle spasms and reduce pain in your abdomen.
  • Antibiotics: Their effectiveness is debated by experts, but antibiotics can help control certain bacteria in your stomach and help with IBS symptoms.
  • Lubiprostone: People with IBS-C may experience improved symptoms on this drug, including less abdominal pain and discomfort, and reduced constipation.
  • Eluxadoline: This antidiarrheal drug helps some people with IBS-D. It targets the intestine to control diarrhea.
  • Linaclotide: This drug is also for people with IBS-C. It can help relieve abdominal pain and increase the frequency of your bowel movements.
  • Peppermint oil-coated capsules: These, too, can help reduce IBS symptoms.

If your doctor prescribes drugs or supplements to help with your IBS symptoms, it’s vital that you take them as directed. That means taking them when and how the instructions say, and observing any limitations to food or drink, or activities, while on the drugs or supplements. If you have side effects from taking a drug or supplement, talk with your doctor. Do not stop taking a drug or supplement without first talking with your doctor.

In addition to drugs and supplements, your doctor may recommend probiotics as part of your treatment plan. These are live microorganisms, often bacteria, that are normally present in your GI tract. Researchers are still studying the use of probiotics to treat IBS, but some studies have found a benefit to including them in your diet or taking them as a supplement.

Another aspect of treatment for some people with IBS is mental health care. Because anxiety, depression, and other mental health conditions can trigger IBS in some people, treating these conditions can help control symptoms. Your doctor may prescribe antidepressants, antianxiety medications, or both depending on your specific condition.


International Foundation for Functional Gastrointestinal Disorders:

National Institute of Diabetes and Digestive and Kidney Diseases:

American Gastroenterological Association:

Irritable Bowel Syndrome Self Help and Support Group: