Irritable bowel syndrome (IBS) is a chronic condition of the digestive system. Its primary symptoms are abdominal pain and changes in bowel habits (eg, constipation and/or diarrhea).
IBS is the most commonly diagnosed gastrointestinal condition and is second only to the common cold as a cause of absence from work. An estimated 10 to 20 percent of people in the general population experience symptoms of IBS, although only about 15 percent of affected people actually seek medical help.
The chronic nature of IBS and the challenge of controlling its symptoms can be frustrating for both patients and health care providers. However, there are treatments and therapies that can help.
There are a number of theories about how and why irritable bowel syndrome (IBS) develops. Despite intensive research, the cause is not clear. The possible theories are listed below.
- Abnormal contractions of the colon and intestines
- After a severe gastrointestinal infection
- Anxiety and stress
- Food sensitivity or allergy
- Heightened sensitivity of the intestines
abnormal contractions of the colon and intestines
One theory suggests that IBS is caused by abnormal contractions of the colon and intestines (hence the term “spastic bowel,” which has sometimes been used to describe IBS). Vigorous contractions of the intestines can cause severe cramps, which may explain why some treatment approaches, such as antispasmodics and fiber (both of which help to regulate the contractions of the colon), relieve symptoms in some cases. However, abnormal contractions do not explain IBS in all situations, and it is unclear whether the contractions are a symptom or cause of the disorder.
after a severe gastrointestinal infection
Some people develop IBS after a severe gastrointestinal infection (eg, Salmonella or Campylobacter, or viruses). However, it is not clear how the infection triggers IBS to develop, and most people with IBS do not have a history of these infections.
anxiety and stress
People with IBS who seek medical help are more likely to suffer from anxiety and stress than those who do not seek help. Stress and anxiety are known to affect the intestine; thus, it is likely that anxiety and stress worsen symptoms. However, stress or anxiety is probably not the underlying cause.
food sensitivity or allergy
Food intolerances are common in patients with IBS, raising the possibility that it is caused by food sensitivity or allergy. This theory has been difficult to prove, although it continues to be studied. The best way to detect an association between symptoms of IBS and food sensitivity is to eliminate certain food groups systematically (a process called an “elimination diet”); this should only be done with the guidance of a doctor or nutritionist. Eliminating foods without assistance can lead to omission of important sources of nutrition. In addition, unnecessary dietary restrictions can have a negative impact on your quality of life.
A number of foods are known to cause symptoms that mimic or aggravate IBS, including dairy products (which contain lactose), legumes (such as beans), and cruciferous vegetables (such as broccoli, cauliflower, Brussels sprouts, and cabbage). These foods increase intestinal gas, which can cause cramps. Several medications also have effects on the intestines that may contribute to symptoms.
heightened sensitivity of the intestines
Many researchers believe that IBS is caused by heightened sensitivity of the intestines. The medical term for this is “visceral hyperalgesia.” This theory proposes that nerves in the bowels are overactive in people with IBS, so that normal amounts of gas or movement are perceived as excessive and painful. Some patients with severe IBS feel better when treated with medications that decrease pain perception in the intestine (such as certain antidepressants). (See ‘Antidepressants’ below.)
Irritable bowel syndrome (IBS) often begins in young adulthood, and is more common in women than in men. The most common symptom of IBS is abdominal pain in association with changes in bowel habits (diarrhea and/or constipation). The symptoms of IBS are listed here.
- Abdominal pain
- Changes in bowel habits
- Others (bloating, gas, and belching, etc)
Abdominal pain — Abdominal pain is typically crampy and varies in intensity. Some people notice that emotional stress and eating worsen the pain, and that having a bowel movement relieves the pain. Some women with IBS notice an association between pain episodes and their menstrual cycle.
Changes in bowel habits — Altered bowel habits are the other symptom typical of IBS. This can include diarrhea, constipation, or alternating diarrhea and constipation. If diarrhea is the more common pattern, the condition is called “diarrhea-predominant” IBS; if constipation is more common, the condition is called “constipation-predominant” IBS.
Diarrhea — A person with irritable bowel syndrome may have frequent loose stools. Bowel movements usually occur during the daytime, and most often in the morning or after meals. Diarrhea is often preceded by a sense of extreme urgency and followed by a feeling of incomplete emptying. About one-half of people with IBS also notice mucous discharge with diarrhea. Diarrhea occurring during the night is very unusual with IBS.
Constipation — Constipation of IBS can be intermittent and last for days. Stools are often hard and pellet-shaped. You may not feel empty after a bowel movement, even when the rectum is empty. This faulty sensation can lead to straining and sitting on the toilet for prolonged periods of time.
Other symptoms — Other symptoms of IBS include bloating, gas, and belching.
Several different intestinal disorders have symptoms that are similar to irritable bowel syndrome (IBS). Examples include malabsorption (abnormal absorption of nutrients), inflammatory bowel disease (such as ulcerative colitis and Crohn disease), celiac disease (in which the body is unable to break down a protein called “gluten”), and microscopic colitis (a condition that involves inflammation of the colon).
Because there is no single diagnostic test for IBS, many clinicians’ approach involves comparing your symptoms to formal sets of diagnostic criteria. However, these criteria are not accurate in distinguishing IBS from other conditions in everyone. Thus, a medical history, physical examination, and select tests can help to rule out other medical conditions.
Is there a test for Irritable bowel syndrome
Tests — Most clinicians order routine blood tests in people with suspected IBS; these tests usually come back normal, but they can help rule out other medical conditions.
Some clinicians also order more invasive tests, such as sigmoidoscopy or colonoscopy, especially in people over age 40 years. These are tests that allow the clinician to see the inside of your colon using a device that is inserted into the rectum.
There are a number of different treatments and therapies for irritable bowel syndrome (IBS). Treatments are often given to reduce the pain and other symptoms of IBS, and it may be necessary to try more than one combination of treatments to find the one that is most helpful for you.
Treating IBS can take time; during this process, it is important to communicate with your health care provider about your symptoms, concerns, and any stressors or other problems that develop.
The first step in treating IBS is usually to monitor your symptoms, daily bowel habits, and any other factors that may affect your bowels. This can help to identify factors that worsen symptoms in some people with IBS, such as lactose or other food intolerances and stress. Keeping a daily diary to track your diet and bowel symptoms can be helpful.
It is reasonable to try eliminating foods that may aggravate IBS, although it’s best to talk to your health care provider before you make significant changes to your diet. Eliminating foods without assistance can potentially worsen symptoms or cause new problems if important food groups are omitted.
Stop Lactose Intake
Many clinicians recommend temporarily eliminating milk products, since lactose intolerance is common and can aggravate IBS or cause symptoms similar to IBS. The greatest concentration of lactose is found in milk and ice cream, although it is present in smaller quantities in yogurt, cottage and other cheeses, and any prepared foods that contain these ingredients.
If your clinician suggests eliminating lactose, you should avoid all lactose-containing products for two weeks. If IBS symptoms improve, it is reasonable to continue avoiding lactose. If symptoms do not improve, you may resume eating lactose-containing foods.
Stop Foods that cause gas
Many foods are only partially digested in the small intestines. When they reach the colon (large intestine), further digestion takes place, which may cause gas and cramps. Eliminating these foods temporarily is reasonable if gas or bloating is bothersome.
The most common gas-producing foods are legumes (such as beans) and cruciferous vegetables (such as cabbage, Brussels sprouts, cauliflower, and broccoli). In addition, some people have trouble with onions, celery, carrots, raisins, bananas, apricots, prunes, sprouts, and wheat.
Increasing dietary fiber
Increasing dietary fiber (either by adding certain foods to the diet or using fiber supplements) may relieve symptoms of IBS, particularly if you have constipation (table 3). By reading the product information panel on the side of the package, you can determine the number of grams of fiber per serving (figure 1). Fiber may also be helpful in some people with diarrhea-predominant symptoms since it can improve the consistency of stools.
A bulk-forming fiber supplement (such as psyllium or methylcellulose) may also be recommended to increase fiber intake since it is difficult to consume enough fiber in the diet. Fiber supplements should be started at a low dose and increased slowly over several weeks to reduce the symptoms of excessive intestinal gas, which can occur in some people when beginning fiber therapy.
Fiber can make some people with IBS more bloated and uncomfortable. If this happens, it is best to decrease fiber intake and consider other laxative treatments for constipation.
Stress and anxiety can worsen IBS in some people. The best approach for reducing stress and anxiety depends upon your situation and the severity of your symptoms. Have an open discussion with your clinician about the possible role that stress and anxiety could be having on your symptoms, and together decide upon the best course of action.
- Some people benefit from formal counseling, with or without antidepressant or antianxiety medications. Other treatments, such as hypnosis and cognitive behavioral therapy, may also be helpful. Hypnosis is a state of altered consciousness that allows you to focus away from your anxiety or stress. Patients who are hypnotized are not sleeping but are actually in a state of heightened imagination, similar to daydreaming. An expert can hypnotize an individual or you can learn self-hypnosis techniques.
- Cognitive behavioral therapy helps you to focus on a particular problem in a limited time period. You learn how your thoughts contribute to anxiety or stress and learn how to change these thoughts.
- Participation in a support group can also be valuable.
- Many patients find that daily exercise is helpful in maintaining a sense of well-being. Exercise can also have favorable effects on the bowels.
Irritable bowel syndrome medications
- Anticholinergic medications
- Antidiarrheal drugs
- Anti-anxiety drugs
- Other medications
Irritable bowel syndrome medications — Although many drugs are available to treat the symptoms of IBS, these drugs do not cure the condition. They are mainly used to relieve symptoms. The choice among these medications depends in part upon whether your primary symptom is diarrhea, constipation, or pain.
As a general rule, medications are reserved for people whose symptoms have not adequately responded to more conservative measures such as changes in diet and fiber supplements. If you do need medication, your health care provider will work with you to figure out the right approach for your situation.
Anticholinergic drugs block the nervous system’s stimulation of the gastrointestinal tract, helping to reduce severe cramping and irregular contractions of the colon.
Drugs in this category include dicyclomine (brand name: Bentyl), hyoscyamine (sample brand name: Levsin), and encapsulated oil of peppermint (sample brand names: Mentha XL, IBgard). These drugs may be particularly helpful when taken preventively (ie, before you have symptoms) and thus are most helpful if you can predict the onset of your symptoms. Common side effects include dry mouth and eyes and blurred vision.
While primarily used to treat depression, many tricyclic agents (TCAs) have a pain-relieving effect in people with IBS. The dose of TCAs is typically much lower than that used for treating depression. It is believed that these drugs reduce pain perception when used in low doses, although the exact mechanism of their benefit is unknown.
TCAs commonly used for pain management include amitriptyline (sample brand names: Elavil, Levate), imipramine (brand names: Tofranil, Impril), desipramine (brand name: Norpramin), and nortriptyline (sample brand names: Pamelor, Aventyl). It is common to experience fatigue when starting a TCA; this is not always an undesirable side effect, since it can help improve sleep when TCAs are taken in the evening. TCAs are generally started in low doses and increased gradually. Their full effect may not be seen for three to four weeks.
TCAs also slow movement of contents through the gastrointestinal tract and may be most helpful in people with diarrhea-predominant IBS.
Another class of antidepressants, the selective serotonin reuptake inhibitors (SSRIs), may be recommended if you have both IBS and depression. Common SSRIs include fluoxetine (sample brand name: Prozac), sertraline (brand name: Zoloft), paroxetine (sample brand name: Paxil), citalopram (brand name: Celexa), and escitalopram (brand name: Lexapro). Other antidepressant medications that may be recommended include mirtazapine (brand name: Remeron), venlafaxine (brand name: Effexor), and duloxetine (brand name: Cymbalta).
The drugs loperamide (sample brand name: Imodium) or diphenoxylate-atropine (brand name: Lomotil) can help slow the movement of stool through the digestive tract. These medications are most helpful if you have diarrhea-predominant IBS. However, clinicians usually recommend that these drugs should only be used as needed rather than on a continuous basis. If you take loperamide, be careful to never exceed the dose on the label unless specifically instructed by your doctor. Taking more than the recommended dose has led to serious heart problems in some people.
Eluxadoline (brand name: Viberzi) has been approved for the treatment of IBS with diarrhea. You should not take this drug if your gallbladder has been removed or if you have a pancreatic or bile duct disorder or severe liver disease. Alcoholic beverages should be limited when taking eluxadoline.
Diazepam (sample brand name: Valium), lorazepam (brand name: Ativan), and clonazepam (brand name: Klonopin) belong to this class of drugs. Anti-anxiety drugs are occasionally prescribed for people with short-term anxiety that is worsening their IBS symptoms. However, these drugs should only be taken for short periods of time since they can be addictive.
Alosetron — Alosetron (brand name: Lotronex) blocks a hormone that is involved in intestinal contractions and sensations. It is approved to treat women with IBS whose predominant symptom is diarrhea. However, it was withdrawn from the market soon after its introduction because of concerns related to safety. It was reintroduced and is currently available for use in women who have severe symptoms that have not responded to conventional treatment, although clinicians must adhere to specific guidelines in order to prescribe it.
Lubiprostone — Lubiprostone (brand name: Amitiza) is available for treatment of severe constipation and IBS in women over 18 years who have not responded to other treatments. It works by increasing intestinal fluid secretion. It is expensive compared with other agents. Further testing is needed to clarify the effectiveness and long-term safety of lubiprostone.
Linaclotide and plecanatide — Linaclotide (Linzess) has been approved for treatment of constipation and IBS in persons over 18 years who have not responded to other treatments. It works by increasing intestinal fluid secretion. It is expensive as compared with other agents (except lubiprostone). Further studies are needed to clarify the effectiveness and long-term safety of linaclotide. Plecanatide (brand name: Trulance) is a similar drug; it is also relatively expensive.
Antibiotics — The role of antibiotics in the treatment of IBS remains unclear. There are some patients whose IBS symptoms benefit from antibiotic treatment. Rifaximin (Xifaxan) has been approved for treatment of IBS without constipation.
Herbs and natural therapies — A number of herbal and natural therapies have been advertised (especially on the internet) for the treatment of IBS. Unfortunately, there is no evidence supporting their benefit. Although small studies may support some of these therapies, the studies are either too small or have major flaws that make definitive conclusions impossible. Below are some of the herbal remedies you may have heard about for treating IBS.
Unproven – There is increasing interest in the possible beneficial effects of “healthy” bacteria (probiotics, eg, acidophilus) in a variety of intestinal diseases, including IBS. Whether supplements containing these bacteria are of any benefit is unproven.
Chamomile tea is of unproven benefit in treating IBS. Furthermore, chamomile can aggravate allergies in people who tend to be allergic to grasses.
Evening primrose oil (a supplement containing gamma linolenic acid) and fennel seeds are also of unproven benefit.
Wormwood is of unproven benefit and may be unsafe; wormwood oil can cause damage to the nervous system. Comfrey is also of unproven benefit and can cause serious liver problems. Iberogast is an herbal product containing nine extracts from medicinal plants . Although thought to be effective in some cases of IBS, cases of acute liver failure have been reported.
It is important to work with a clinician to monitor your symptoms over time. If symptoms change, further testing may be recommended. Over time, less than 5 percent of people diagnosed with irritable bowel syndrome (IBS) will be diagnosed with another gastrointestinal condition.
Although IBS can cause substantial physical discomfort and emotional distress, most people are able to control their symptoms and live a normal life without developing serious health problems.
- Malfertheiner P. STW 5 (Iberogast) Therapy in Gastrointestinal Functional Disorders. Dig Dis 2017; 35 Suppl 1:25.
- Jailwala J, Imperiale TF, Kroenke K. Pharmacologic treatment of the irritable bowel syndrome: a systematic review of randomized, controlled trials. Ann Intern Med 2000; 133:136.
- Spiller RC. Postinfectious irritable bowel syndrome. Gastroenterology 2003; 124:1662.
- Cremonini F, Delgado-Aros S, Camilleri M. Efficacy of alosetron in irritable bowel syndrome: a meta-analysis of randomized controlled trials. Neurogastroenterol Motil 2003; 15:79.
- Drossman DA, Camilleri M, Mayer EA, Whitehead WE. AGA technical review on irritable bowel syndrome. Gastroenterology 2002; 123:2108.
- Drossman DA. Functional abdominal pain syndrome. Clin Gastroenterol Hepatol 2004; 2:353.
- Liu JP, Yang M, Liu YX, et al. Herbal medicines for treatment of irritable bowel syndrome. Cochrane Database Syst Rev 2006; :CD004116.
- Spanier JA, Howden CW, Jones MP. A systematic review of alternative therapies in the irritable bowel syndrome. Arch Intern Med 2003; 163:265.