Table 6.1-10. Algorithm for the management of IBS

Initial management

Further pharmacologic treatment (dose)

Mechanism

Indication

Evidence

IBS with predominant constipation (IBS-C)

– To improve IBS symptoms: Water-soluble fiber (psyllium >12 g daily)

– To improve stool consistency, as adjuvant treatment (only as needed): Osmotic laxatives: Polyethylene glycol 17 g/d; magnesium hydroxide 15-30 mL/d

Linaclotide (145-290 microg/d) and plecanatide (3-6 mg/d)

Guanylate C agonist

Pain, discomfort, stool consistency, straining

H

Lubiprostone (8-24 microg bid)

Chloride channel activator

Bloating, pain, straining, frequency, consistency

M

Antispasmodics: Dicyclomine (20-40 mg qid), pinaverium (50-100 mg tid), trimebutine (200 mg tid)

Anticholinergic or calcium channel blocker

Pain; may worsen constipation

VL

Antidepressants: Citalopram (20 mg/d), fluoxetine (20 mg/d), paroxetine (20-40 mg/d)

SSRIs

Pain, depression

M

IBS with predominant diarrhea (IBS-D)

Low FODMAP diet for 4-8 weeks

Loperamide (2-4 mg; max, 12 mg/d; only as needed, not continuously)

Mu-opioid receptor agonist

Diarrhea (no effect on pain) as rescue medication

VL

Eluxadoline (75-100 mg bid)

Mixed mu-opioid, delta-opioid, and kappa-opioid receptor agonist

Diarrhea, pain

M

Diphenoxylate/atropinea: Diphenoxylate 5 mg, then 2.5 mg after each loose bowel movement (max, 20 mg/d)

Mu-opioid receptor agonist and anticholinergic

Diarrhea, pain

M

Rifaximin (400-550 mg bid for 10-14 days)

Antimicrobial

Diarrhea, pain

M

Antidepressants (see IBS-C): Amitriptyline (10-20 mg/d), desipramine (25 mg/d), imipramine (25 mg/d)

TCAs

Diarrhea, pain, constipation

H

IBS with mixed bowel habits (IBS-M)

To improve stool consistency:

− Water-soluble fiber (psyllium >12 g daily)

− Low FODMAP diet (also improves bloating)

− Stop laxatives

See IBS-D and IBS-C

See IBS-D and IBS-C

See IBS-D and IBS-C

See IBS-D and IBS-C

Bloating

Low FODMAP diet

IBS-C: Linaclotide and lubiprostone

See IBS-C

See IBS-D and IBS-C

See IBS-D and IBS-C

IBS-D: Rifaximin and eluxadoline

See IBS-D

See IBS-D and IBS-C

See IBS-D and IBS-C

a In North America available under trade name Lomotil.

FODMAP, fermentable oligosaccharides, disaccharides, monosaccharides, and polyols; IBS, irritable bowel syndrome; H, high quality; M, moderate quality; SSRI, selective serotonin reuptake inhibitor; TCA, tricyclic antidepressant; VL, very low quality.