Laxatives for IBS with Constipation (IBS-C)

A laxative is a drug that increases bowel function.  There are many laxatives available without a prescription.  The most commonly used types include: 

  • Osmotic – polyethylene glycol (PEG) 3350 (such as Miralax®)
  • Stimulant – senna cascara, bisacodyl (such as Dulcolax®, Correctol®)
  • Magnesium-based – milk of magnesia

Of these, only PEG 3350 has been evaluated in clinical trials in people with IBS-C. PEG 3350 has been shown to improve stool texture and frequency. Stool frequency is a term describing how often someone moves their bowels. This drug does not improve the abdominal pain/discomfort symptoms of IBS. In fact, many people report an increase in their abdominal symptoms when taking this medication. The lack of overall IBS symptom improvement makes this less recommended as a treatment for IBS-C. Common side effects include diarrhea, abdominal cramping, bloating, and nausea. In rarer cases, dehydration and electrolyte disturbances have occurred.

Last modified on May 25, 2021

Adapted from IFFGD Publication #168 Current Pharmacologic Treatments for Adults with Irritable Bowel Syndrome By: Darren M. Brenner, MD, Associate Professor of Medicine and Surgery, Northwestern University -Feinberg School of Medicine, Chicago, Illinois; Adapted from an article by: Tony Lembo, MD, Professor, of Medicine and Rebecca Rink MS, Beth Israel Deaconess Medical Center, Harvard Medical School, MA; Edited by: Lin Chang, M.D., Professor of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA

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IFFGD is a nonprofit education and research organization. Our mission is to inform, assist, and support people affected by gastrointestinal disorders.

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