Management of Irritable Bowel Syndrome

Patient Guideline Summary

Publication Date: January 1, 2021

Last Updated: April 9, 2024

Objective

This patient summary means to summarize key recommendations from the American College of Gastroenterology (ACG) guideline for the management of irritable bowel syndrome. This patient summary is limited to adults 18 years of age and older and should not be used as a reference for children.

Overview

Irritable bowel syndrome is a common disorder that affects the gut. It often weakens the patient and lasts for a long time.
We will use the abbreviation IBS throughout this summary to refer to irritable bowel syndrome.
Symptoms include abdominal pain at least once weekly together with a change in stool frequency, or stool form, and/or relief or worsening of abdominal pain related to defecation. Bloating can also happen, but it is not necessary for the diagnosis.
IBS has different types:
- IBS with constipation (IBS-C)
- IBS with diarrhea (IBS-D)
- IBS with mixed bowel habits (IBS-M)
IBS affects women more than men.
IBS affects individuals younger than 50 years more than older people.
IBS negatively affects patients’ quality of life.
This patient summary focuses on important points in the diagnosis and management of IBS.

Evaluation and Diagnosis

If you have IBS and diarrhea, your doctor will order serologic testing (blood tests that look for antibodies in the blood) to exclude celiac disease (CD).

CD is an immune-related disease caused by foods containing gluten in certain persons with a problem in their genes. Its symptoms resemble IBS.

If you have IBS and diarrhea, your doctor may order tests to look for certain proteins in the stool to exclude inflammatory bowel disease (examples are Crohn's disease and ulcerative colitis). These proteins are stool calprotectin (or stool lactoferrin) and/or C-reactive protein (CRP).

ACG recommends against testing for stool pathogens (germs) on a regular basis.

The exception to the previous statement is patients at risk of Giardia (a parasite) infection that causes giardiasis (a disease caused by Giardia intestinalis that lives in the ground, food, dogs, and contaminated water and causes symptoms including diarrhea).

According to the Centers for Disease Control and Prevention (CDC), people at risk of giardiasis include:
- Children in childcare.
- Close contact with people with giardiasis
- People who drink untreated water from lakes or wells where Giardia may live.
- Campers and hikers who drink unsafe water.
- People who swallow water when swimming.
- People who are exposed to human feces from sexual contact.
- Travelers to areas where Giardia lives.
Giardiasis is more common in developing countries, so testing is more important in these countries.
If you are a patient with IBS symptoms younger than 45 years without warning signs, you should not get a routine colonoscopy (inserting a thin telescope into your colon).
Your doctor may be able to diagnose IBS by taking a good medical history, doing a physical examination, and ordering minimal testing.

The history involves asking you about abdominal pain or altered bowel habits.

Your doctor may categorize your IBS based on an accurate IBS subtype. These subtypes are based on your most common stool form.

This categorization may be based on a scale called the Bristol Stool Form Scale (BSFS).

According to this scale:
- You need to determine the primary stool consistency on the days you report abnormal bowel movements.
- You should do this when you are off of medication since medication can affect bowel patterns.
- You should perform daily diaries for 2 weeks to get the most accurate assessment.

You do not need testing for food allergies or food sensitivities if you have IBS unless there are repeated symptoms suggesting a food allergy.
Food allergies in adults are not common, and the tests used are not all that reliable (e.g., serum IgE levels and the skin prick test).
Your doctor may order anorectal physiology testing (testing the function of the anal canal and rectum) if you are a patient with IBS and:
- have symptoms suggest a pelvic floor disorder and/or
- have constipation not responsive to standard medical therapy.

Poor function of the anorectal muscles occurs in all subtypes of IBS.

Management

If you are a patient with IBS, your doctor may suggest you alter your diet. This may include a low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) diet to improve global symptoms.

FODMAPs are chemicals naturally occurring in food that ferment in the colon, producing alcohol and gases that can lead to meal-related symptoms in patients with IBS.

If you are a patient with IBS, your doctor will likely recommend soluble fiber, but not insoluble fiber, to treat IBS symptoms.

The following table lists examples of soluble and insoluble fiber.

Food rich in soluble fiber	Food rich in insoluble fiber
psyllium, oat bran, barley, and beans	wheat bran, whole grains, and some vegetables

ACG recommends against the use of antispasmodics (drugs that prevent or treat muscle spasms, especially bowl spasms) to treat IBS symptoms.
The ACG guideline focuses on antispasmodics approved for use in the United States.
Peppermint may provide relief from global IBS symptoms.
ACG suggests against the use of:
- Probiotics for the treatment of global IBS symptoms.
- PEG (polyethylene glycol) products to relieve the global IBS symptoms if you have IBS-C.
- Bile acid sequestrants (prescription drugs also used to lower cholesterol) to treat global IBS-D symptoms.
- The use of fecal transplant for the treatment of global IBS symptoms.
If you are a patient with IBS-C, your doctor will usually prescribe a drug belonging to a family called “chloride channel activators” to treat your global IBS-C symptoms.
- This means your doctor can prescribe 8 mg of lubiprostone two times per day.
- Things to consider when taking lubiprostone:
  - You may notice a delay in the initial effect, but improvement happens over time.
  - Take lubiprostone with meals to decrease nausea (feeling like throwing up).
Your doctor can prescribe a drug belonging to a family called “guanylate cyclase activators” to treat your global IBS-C symptoms
- There are currently two Food and Drug Administration (FDA)-approved agents for the treatment of IBS-C. There are linaclotide 290 mg and plecanatide 3 mg.
If you are an adult woman younger than 65 years with IBS-C, your doctor can prescribe tegaserod. It is the only US FDA-approved 5-HT4 receptor agonist used for the treatment of adult women younger than 65 years with IBS-C.
Cardiovascular risk factors to consider when evaluating a woman with IBS-C for possible tegaserod use:
- History of cardiovascular disease
- History or presence of hypertension (elevated blood pressure)
- Active smoking
- History or presence of diabetes mellitus
- History of the presence of hyperlipidemia (an abnormally high concentration of fat in the blood)
- Age over 55 years at baseline
- Obesity (body mass index [BMI] (a measure that relates body weight to height) over 30 kg/m² at baseline).
Your doctor can prescribe an antibiotic called rifaximin to treat your global IBS-D symptoms. It is a US FDA-approved antibiotic for the treatment of IBS-D.
- The use of rifaximin is based on the theory that some patients with IBS-D have an abnormal microbiome (the microorganisms that live in your gut).
If you are a woman with IBS-D and severe symptoms that have failed conventional therapy, your doctor can prescribe alosetron to relieve global IBS-D symptoms.
- Alosetron stops the action of 5-HT3 so it slows the intestinal transit.
If you have global IBS-D symptoms, your doctor may prescribe a drug called eluxadoline.
- The recommended dose is 100 mg by mouth. A lower dose (75 mg) is also recommended for some patients.
Your doctor can prescribe tricyclic antidepressants (TCAs) to treat global symptoms of IBS.
Your doctor may use gut-directed psychotherapies (GDPs) to treat global IBS symptoms. These include, for example, relaxation training or concentrating on changing unhelpful thoughts, or using techniques that change pain perception.

The following table summarizes the recommended medications/treatments for IBS-C, IBS-D, and global symptoms:

IBS-C	IBS-D	All IBS (Global Symptoms)
chloride channel activators	rifaximin	Dietary adjustments & Soluble Fiber
guanylate cyclase activators	alosetron (in select women)	Peppermint
tegaserod (in select women)	mixed opioid agonists/antagonists	tricyclic antidepressants
		gut-directed psychotherapies

Abbreviations

5-HT3: 5-hydroxytryptamine-3
ACG: American College Of Gastroenterology
BMI: Body Mass Index
BSFS: Bristol Stool Form Scale
CD: Celiac Disease
CDC: Centers For Disease Control And Prevention
CRP: C-reactive Protein
CV: Cardiovascular
FDA: Food And Drug Administration
FODMAPs: Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols
GDPs: Gut-directed Psychotherapies
IBS: Irritable Bowel Syndrome
PEG: Polyethylene Glycol
TCAs: Tricyclic Antidepressants

Source Citation

Lacy BE, Pimentel M, Brenner DM, Chey WD, Keefer LA, Long MD, Moshiree B. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. Am J Gastroenterol. 2021 Jan 1;116(1):17-44. doi: 10.14309/ajg.0000000000001036. PMID: 33315591.

Disclaimer

The information in this patient summary should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.