Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder affecting up to 15% of people in the United States. Common symptoms include abdominal pain, cramping, diarrhea, constipation, gas, and bloating. Living with IBS can significantly affect a person's quality of life.

No one knows what causes IBS, and most people with IBS are not cured. The goal of treatment is to manage symptoms and reduce the frequency and severity of flare-ups.

The most common approach is making dietary changes—eliminating or reducing problem foods. Certain supplements and over-the-counter and prescription medications also may help ease symptoms. Stress management techniques, such as yoga, meditation, and acupuncture, and psychological therapy like cognitive behavioral therapy and biofeedback can also help.


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What is irritable bowel syndrome?

Irritable bowel syndrome (IBS) is a gastrointestinal disorder in which your gut is more sensitive, and the digestive muscles contract abnormally. IBS usually begins in early adulthood and affects twice as many women as men.

People with IBS usually have abdominal pain and frequent changes in bowel habits (diarrhea, constipation, or alternating between the two). Other common symptoms include:

  • bloating and gas
  • the urge to move the bowels but being unable to do so
  • incomplete bowel movements
  • an urgent need to move the bowels

IBS has three main subtypes:

Constipation-predominant IBS (IBS-C). People with IBS-C experience abdominal pain, infrequent bowel movements, lumpy or hard stools, and straining or incomplete emptying during bowel movements.

Diarrhea-predominant IBS (IBS-D). People with IBS-D have abdominal pain, frequent bowel movements, loose and watery stools, or frequent feelings of bowel urgency.

Mixed IBS (IBS-M). This type involves episodes of both constipation and diarrhea, as well as abdominal pain. It’s common for people with IBS-M to go back and forth between the two within the same month, week, or even day.

The cause of IBS is unknown. Some studies suggest that the colon’s nerves are more sensitive in people with IBS.

IBS is unrelated to other diseases and does not increase the risk of colon cancer.

What are common IBS symptoms?

People with irritable bowel syndrome (IBS) will experience some or all of the following symptoms: 

  • Mild or severe abdominal pain, discomfort, or cramping that usually goes away after a bowel movement 
  • Periods of diarrhea or constipation or alternating between these two symptoms 
  • Bloating, gassiness, or a feeling of having a distended abdomen 
  • Mucus in bowel movements 
  • Feeling as though a bowel movement is incomplete 

Many people tend to develop their own pattern of symptoms. For example, some have mostly diarrhea, some have constipation, and others have abdominal pain without a significant change in bowel movements.

The severity of IBS flare-ups also varies. Some people experience symptoms that come and go and are mildly annoying. Others have severe daily bowel problems that affect their ability to work, sleep, and enjoy life. 

In addition, symptoms may change over time. A person may have severe symptoms for several weeks and then feel well for months or years. 

How is IBS diagnosed?

There is no test for IBS. Your doctor will diagnose IBS after taking a careful history from you and after you have been tested and other disorders that can cause similar symptoms have been ruled out. These tests might include: 

  • abdominal exam to check for tenderness and any abnormalities of the internal organs
  • blood tests 
  • stool sample to check for blood or evidence of infection 
  • sigmoidoscopy, in which a flexible, lighted tube with a tiny camera on the end is inserted into the rectum and colon
  • colonoscopy, a more thorough examination of the entire colon 

Your doctor also may suggest that you stop eating or drinking certain foods for up to three weeks to determine how your diet contributes to your symptoms.

What medications can treat IBS?

There is no cure for irritable bowel syndrome (IBS). The goal is to reduce the frequency and severity of flare-ups and manage symptoms. Depending on your subtype of IBS, your doctor may prescribe over-the-counter or prescription medications and supplements to help.

Constipation-predominant IBS (IBS-C). For IBS-C, your doctor will likely start by recommending over-the-counter fiber supplements and osmotic laxatives. Fiber helps regulate bowel movements and reduces abdominal discomfort from constipation. Fiber supplements can help add extra fiber to your diet if you have trouble eating enough high-fiber foods. They contain soluble fibers such as psyllium, methyl-cellulose, or polycarbophil. Supplements come in capsules, powders you mix with water, and chewable tablets. Popular brands include Benefiber, Metamucil, Citrucel, and Konsyl. Osmotic laxatives increase the water held in the stool, which makes it easier to pass. Polyethylene glycol (Miralax) and magnesium products (Milk of Magnesia) are common brands.

Prescription drugs called secretagogues are also available if over-the-counter options don’t provide enough relief. They increase the flow of fluids into the intestine, which makes stools softer and easier to pass and reduce pain and bloating. Examples include lubiprostone (Amitiza), linaclotide (Linzess), plecanatide (Trulance), and tenapanor (Ibsrela).

Diarrhea-predominant IBS (IBS-D). People with IBS-D often begin treatment with over-the-counter loperamide (Imodium) to help reduce the frequency and urgency of bowel movements and produce firmer stool.

Prescription antispasmodics like hyoscyamine (Levsin) and dicyclomine (Bentyl) can provide short-term pain relief and discomfort related to muscle spasms in the colon. Other prescription medications for IBS-D include:

  • Rifaximin (Xifaxan), an antibiotic that attacks bacteria in the small and large intestines that can cause diarrhea.
  • Eluxadoline (Viberzi), which helps relieve diarrhea and abdominal pain by decreasing bowel activity.
  • Alosetron (Lotronex), a drug available for women with severe IBS-D.

Antidepressants like tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), and serotonin and norepinephrine reuptake inhibitors (SNRIs) also are sometimes prescribed for symptom relief. 

What foods can trigger IBS?

What you eat (and don’t eat) often significantly impacts IBS symptoms. Certain foods can cause flare-ups or make symptoms worse.

IBS trigger foods vary from person to person, but the following often are associated with symptoms:

  • alcohol
  • caffeine (coffee, tea, regular and diet soft drinks)
  • chocolate
  • dairy products
  • fermented foods (such as sauerkraut)
  • fried and fatty foods
  • soy foods.

People with IBS may also benefit from limiting gas-producing foods, such as:

  • alcohol
  • apricots
  • bagels
  • beans
  • broccoli
  • Brussels sprouts
  • caffeine
  • carrots
  • celery
  • garlic
  • onions
  • prunes
  • raisins

Keeping a food diary can help identify trigger foods. Every time you have IBS symptoms, record the following information:

  • date and time that symptoms began and ended
  • description of symptoms, such as stomach pain, bloating, constipation, etc.
  • rating the symptoms on a 1 to 10 scale, with 1 being little to no discomfort and 10 being severe
  • type and amount of food you consumed that day

Once you have a list of suspected trigger foods, you can try a trial-and-error approach known as an elimination diet. First, eliminate all suspected trigger foods from your diet for two or more weeks. If your symptoms improve, bring back each of the eliminated foods, one at a time, and record the results in your food diary. If your symptoms return, you’ve found an offending food.

You might also find that eating specific amounts of the trigger foods causes symptoms; in that case, you can adjust portions. Consider working with a nutritionist to help with the process.

What are FODMAPs and how might a low-FODMAP diet help?

Besides identifying trigger foods that can cause flare-ups, people with IBS can try a low- FODMAP diet. FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These are short-chain carbohydrates that the small intestine does not absorb well in people with IBS, and can lead to bloating, gas, abdominal pain, and diarrhea.

The following foods contain FODMAPs:

  • oligosaccharides, including fructans (wheat, onions, garlic) and galactans (beans, lentils, soybeans)
  • disaccharides, including lactose (milk and other dairy products)
  • monosaccharides, including fructose (fruit, such as apples, pears, peaches, cherries, pears, and watermelon, and sweeteners like honey and agave nectar)
  • polyols, including sorbitol and mannitol (some fruits, vegetables, such as cauliflower, mushrooms, and peas, and artificial sweeteners, such as sorbitol, mannitol, xylitol, maltitol, and isomalt, found in sugar-free gum, mints, and cough medicines and drops.)

The idea behind the low FODMAP diet is to limit only the problematic foods in a category—not all of them. You may tolerate some foods better than others.

Consult a registered dietician if you are considering a low FODMAP diet. They will help you gradually eliminate FODMAPs from your diet, and then add the carbohydrates back in one at a time to identify the ones that are problematic for you.

Can stress and anxiety trigger IBS?

The brain and gut are closely connected. Stress and anxiety do not cause IBS, but they can increase the frequency and severity of symptoms. Psychological therapy, and relaxation and stress reduction techniques may help relieve IBS symptoms in some people.

Cognitive behavioral therapy (CBT). CBT helps you increase awareness of your thoughts and behavior and learn how to change your reactions to stressful situations. CBT can help people with IBS avoid anticipating symptoms that can trigger the body’s “fight or flight” response and make symptoms worse. Instead, people learn to use relaxation responses like deep breathing.

Biofeedback. Biofeedback is a mind-body therapy that involves training people to control the physiological reactions—such as increased muscle tension, blood pressure, and heart rate—that occur in response to stress. Through a trial-and-error approach, you gradually learn to change your body’s reaction under stress, including pain and discomfort from IBS.

Hypnotherapy. This relaxation technique may help people with IBS by calming the autonomic nervous system, which controls bodily functions like breathing, heartbeat, and digestive processes.

Support groups. Talking with others who deal with IBS can help people cope. One resource is the online community IBS Patient Support Group, which offers support, community discussions, and IBS information.

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