Treatment Guideline Chart
Irritable bowel syndrome is a common chronic gastrointestinal condition characterized by abdominal pain and bloating with altered bowel habits.
There are no identifiable physical, radiologic or lab abnormalities indicative of organic disease.
Symptoms may be exacerbated by stress, alcohol or food.

Irritable%20bowel%20syndrome Treatment

Principles of Therapy

  • The cornerstone of IBS therapy is a strong physician-patient relationship, education and reassurance which may reduce the need for further consultation and may be therapeutic

Establishing Therapeutic Relationship 

  • Listening to patient: Address concerns, identify and discuss patient’s beliefs
  • Explaining the disease state: Nature, causes, aggravating factors and prognosis
  • Reassuring patient of the benign nature of IBS

General Therapeutic Principles for Pharmacotherapy in IBS 

  • Goal of therapy is to improve global IBS symptoms which include abdominal discomfort/bloating and altered bowel habits
    • Not only should therapy be directed at altered bowel habits (eg constipation, diarrhea, fecal urgency) but should also address abdominal discomfort
  • Therapy should be given to those in whom there is an impact on quality of life from IBS symptoms

Symptom-Based Descriptions 

  • IBS symptoms may fluctuate over time and vary between individuals
    • IBS with constipation often changes to constipation alone or IBS alternating between constipation and diarrhea or any other functional GI disorders over time
  • Therefore, symptom-based descriptions may be used to guide management (eg IBS with diarrhea or IBS with constipation)


A. Pharmacological Therapy for IBS with Constipation (IBS-C) 

Bulk-Producing Laxatives 

  • Eg Ispaghula (Psyllium), Methylcellulose, Polycarbophil
  • Patients with constipation should first attempt to increase fiber in their diet; if this does not improve symptoms, then addition of Ispaghula may be tried
    • A few small studies conducted in older adults showed similar effectiveness of Polycarbophil and Methylcellulose to Ispaghula
  • Ispaghula husk is moderately effective for constipation and is associated with an overall improvement in patients with IBS
  • Patients should be warned that bloating and abdominal distension may occur especially at the start of fiber therapy but may decrease over time or with a dose reduction
  • Wheat/corn bran have not been found to improve global IBS symptoms compared to placebo

Osmotic Laxatives

  • Eg Lactulose, Milk of Magnesia, Sorbitol, Magnesium citrate, polyethylene glycol (PEG)
  • If dietary fiber and bulk-producing laxatives are not effective, then osmotic laxatives may be tried though there are no published studies with these laxatives in IBS-C patients and should not be given to patients with renal dysfunction
  • PEG improves frequency and consistency of bowel movement but not pain and other symptoms of IBS
    • Is widely available and has lesser side effects compared with Lactulose or Milk of Magnesia

Guanylate Cyclase-C Receptor Agonists


  • Recommended for patients with moderate to severe IBS-C and also for overall symptom improvement
    • Randomized controlled trials showed improvement in global symptoms of IBS


  • Recommended for overall symptom improvement in patients with IBS-C
  • Has comparable efficacy and safety as Linaclotide

Type 2 Chloride Channel Agonist 


  • Improves stool consistency and abdominal pain in women at 1 month of use and is better than placebo in improving abdominal bloating at 3 months
    • Initial response may be delayed but improvement in global symptoms is maintained or increases over time

Serotonin 5-HT4 Receptor Agonists


  • A prokinetic that has been shown in clinical trials to be effective for chronic constipation
    • An alternative to patients unresponsive to conventional laxatives
  • Further studies in patients with IBS-C are needed to confirm efficacy and safety


  • Has been shown to be more effective than placebo at relieving global IBS symptoms in women with IBS-C and IBS-M
  • An alternative agent in women <65 years old with ≤1 risk factor for cardiovascular (CV) disease and without a history of ischemic CV disease who have inadequately responded to secretagogues

Sodium/Hydrogen Exchanger 3 (NHE3) Inhibitor 


  • Clinical trials showed improvement in spontaneous bowel movements and abdominal pain when compared with placebo in patients with IBS-C 

B. Pharmacological Therapy for IBS with Diarrhea (IBS-D)


Synthetic Opiates 

  • Eg Diphenoxylate/Atropine, Eluxadoline and Loperamide
  • May be used in patients suffering from diarrhea as they can reduce loose stools, urgency and fecal soiling
  • Loperamide
    • Significantly improves diarrheal symptoms in patients with IBS but is not recommended for continuous use due to lack of significant overall symptom improvement in IBS patients 
  • Eluxadoline
    • Mu- and kappa-opioid receptor agonist, and delta-opioid receptor antagonist in the enteric nervous system
    • May be considered for overall symptom improvement in patients with IBS-D
    • Contraindicated in patients with history of alcohol abuse/addiction, biliary duct obstruction, pancreatitis, severe liver problems and patients who underwent cholecystectomy due to increased risk of pancreatitis

Bile Acid Sequestrants 

  • Eg Cholestyramine, Colesevelam, Colestipol 
  • May be considered in a subgroup of IBS patients with diarrhea secondary to cholecystectomy or bile acid malabsorption

Serotonin 5-HT3 Receptor Antagonists 


  • Has been shown to be more effective than placebo at relieving global IBS symptoms in female IBS patients with diarrhea
    • United States Food and Drug Administration (US FDA) approval only for use in women with severe diarrhea-predominant IBS for 6 months and who have failed to respond to conventional IBS therapy
  • Decreases gut transit in non-IBS and IBS patients, enhances basal sodium and fluid absorption, and relaxes the left colon thereby reducing the perception of fluid distension in patients with IBS
  • Cases of ischemic colitis and serious constipation complications have occurred with the use of Alosetron; therefore, the patient and physician need to carefully consider risk/benefit profile before deciding to use


  • Found to be helpful in improving stool consistency, urgency, and frequency and bloating in IBS-D


  • A promising therapeutic agent for patients with IBS-D; a study demonstrated higher rates of relief of overall IBS symptoms in male patients with IBS-D than placebo
  • Inhibits 5-HT3 receptor antagonism in the vagal afferent neurons and myenteric plexus
  • Trials show incidence of constipation is lower among patients treated with Ramosetron and no ischemic colitis was reported


  • Rifaximin is a safe and effective agent for the treatment of abdominal pain and diarrhea in patients with IBS-D 
  • Consider evaluating for a severe infectious diarrhea, eg C difficile enterocolitis, if diarrhea does not improve or worsens following treatment with Rifaximin

C. Pharmacological Therapy for Abdominal Pain and Bloating 


  • May be used in patients of all IBS subtypes for the treatment of abdominal pain and spasms 
    • May be considered for pain/bloating especially when exacerbated by meals
  • The smooth muscle relaxants, Cimetropium, Hyoscine, Hyoscyamine, Dicyclomine, Mebeverine, Octylonium bromide (Otilonium Br), Pinaverium bromide, Trimebutine, and Peppermint oil may be more effective than placebo in improving IBS symptoms
  • Best used on a short-term as-needed basis, up to 3x/day for acute attacks of pain or before meals if there are postprandial symptoms

Tricyclic Antidepressants (TCAs) 

  • Though not an approved indication, low-dose TCAs may be considered for severe IBS in which pain is more constant or disabling
  • TCAs have been shown to significantly improve abdominal pain and symptoms in IBS patients compared with placebo
    • Relieve abdominal pain associated with IBS independent of their effect on mood
    • May be more effective in IBS-D
  • Effect may be due to a reduction in the sensitivity of peripheral nerves or to alterations in the brain

Selective Serotonin Reuptake Inhibitors (SSRIs) 

  • SSRIs have been shown to be more effective than placebo at relieving global IBS symptoms
  • Also proven to reduce abdominal pain greatly in IBS-C
  • Recommended only when there is treatment failure after TCA therapy
  • Advise patients to strictly follow up after 4 weeks and every 6-12 months while on SSRI therapy


  • Some clinical trials have shown that a nonabsorbable antibiotic, Rifaximin, is more effective for global improvement of IBS and bloating as compared to placebo
  • No studies are available to support long-term use of antibiotics for the management of IBS
  • There are not enough available evidence to support the use of Neomycin, Metronidazole, and Clarithromycin for improvement of symptoms of IBS

Non-Pharmacological Therapy

Behavioral Therapy  

  • Identify signs of a psychological disorder as psychological disorders and IBS are often comorbid conditions
  • Consider administering psychological treatments in cases wherein a significant association between stress and symptoms exist or in patients who are unresponsive after 3-6 months of treatment with 1st- or 2nd-line agents
  • Psychological treatments that have been used include relaxation therapy, biofeedback, hypnotherapy, cognitive therapy and psychotherapy
  • Various clinical trials have shown that cognitive behavioral therapy, dynamic psychotherapy and hypnotherapy are beneficial for IBS patients except relaxation therapy
  • Cognitive behavioral therapy has been found to be more effective than placebo in relieving individual IBS symptoms
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