Constipation Medication

Updated: Mar 30, 2020
  • Author: Marc D Basson, MD, PhD, MBA, FACS; Chief Editor: BS Anand, MD  more...
  • Print

Medication Summary

Medications to treat constipation include bulk-forming agents (fibers), emollient stool softeners, rapidly acting lubricants, prokinetics, laxatives, osmotic agents, and prosecretory drugs. Fiber is arguably the best and least expensive medication for long-term treatment, although enthusiasm for the use of polyethylene glycol as first-line therapy in chronic constipation is increasing.

NOTE:  In January 2014, the FDA issued a warning that exceeding one dose of OTC sodium phosphate products for constipation over a course of 24 hours may cause serious harm to the kidneys and heart and, in rare cases, may be fatal. [24, 25] Using more than the recommended dose of these products can cause severe dehydration and changes in serum electrolyte levels. Individuals who may be at higher risk for potential adverse events include young children; patients older than 55 years; patients who are dehydrated; patients with kidney disease, bowel obstruction, or inflammation of the bowel; and patients who are using medications that may affect kidney function. [24, 25]

Emollient stool softeners are easier to use, but they lose their effectiveness with chronic administration. These drugs are best used for prophylaxis in a short-term setting, such as in patients receiving a postoperative narcotic prescription.

Rapidly acting lubricants and laxatives, including over-the-counter products, are often used to treat acute and chronic constipation.

Polyethylene glycol is simple to use and is more effective than placebo in the management of chronic constipation; however, the effects of chronic therapy with polyethylene glycol over decades are still not well studied.

Newer therapies for constipation include the prokinetic agent prucalopride, the osmotic agent lubiprostone, and the guanylate cyclase C (GC-C) agonists, linaclotide and plecanatide.


Laxatives, Bulk-Producing

Class Summary

Bulk-forming agents are used for long-term prophylaxis, treatment of constipation, or both in patients without anatomic outlet obstruction.

Psyllium (Metamucil, Fiberall, Bulk-K, Fibro-XL)

Psyllium dosages vary depending on whether the preparations contain sugar or are sugar-free (the former are 50% sugar). These preparations must be taken with water, or they may cause obstruction.

Methylcellulose (Citrucel)

Theoretically, nonfermentable products such as methylcellulose, which produce less gas, are better tolerated than psyllium. Occasionally, patients who cannot tolerate one preparation may do well with another product.


Laxatives, Stool Softener

Class Summary

Emollient stool softeners are used for prophylaxis against constipation in acute and subacute settings.

Docusate (Colace, Docu-Soft, Dok)

Docusate is indicated for patients who should avoid straining during defecation. It allows incorporation of water and fat into stools, causing stools to soften. Tachyphylaxis develops with long-term use. Docusate is effective acutely. It does not induce defecation.


Laxative, Stimulant; Laxative, Stool Softener

Class Summary

Emollient stool softeners cause stool to soften; stimulants increase the peristaltic activity in the gastrointestinal (GI) system.

Senna concentrate/docusate (Peri-Colace, Dok Plus, Senokot-S)

Docusate sodium allows incorporation of water and fat into stool, causing stool to soften. Sennosides induce defecation by acting directly on the intestinal mucosa or the nerve plexus, which stimulates peristaltic activity, increasing intestinal motility. The combination usually produces action 8-12 hours after administration.


Laxatives, Saline

Class Summary

Saline laxatives are used for acute treatment of constipation in the absence of bowel obstruction.

Magnesium hydroxide (Phillips Milk of Magnesia, Fleet Pedia-Lax Chewable)

Magnesium hydroxide causes osmotic retention of fluid, which distends the colon and increases peristaltic activity; it also promotes emptying of the bowel.

Magnesium citrate (Citroma)

Magnesium citrate causes osmotic retention of fluid, distending the colon and increasing peristaltic activity; it promotes emptying of the bowel. The drug works within 3 hours given orally (PO) or 15 minutes given rectally (PR). It may cause electrolyte imbalance, especially in young children or patients with renal insufficiency.

Magnesium sulfate

Magnesium sulfate causes osmotic retention of fluid, which distends the colon and increases peristaltic activity; it promotes emptying of the bowel.


Laxatives, Lubricant

Class Summary

Lubricant laxatives are used for acute or subacute management of constipation. They lubricate the intestine and facilitate the passage of stool by decreasing water absorption from the intestine.

Mineral oil (Fleet, Kondremul)

Mineral oil is gentler than some other rapidly acting laxatives. It generally works within 8 hours. Long-term use is accompanied by concerns about lipid pneumonia, lymphoid hyperplasia, and foreign body reactions.


Laxatives, Other

Class Summary

These agents elicit various pharmacologic effects resulting in increased intestinal fluid and thereby decrease constipation symptoms.

Lubiprostone (Amitiza)

Lubiprostone is a locally acting chloride channel activator that enhances a chloride-rich intestinal fluid secretion without altering sodium and potassium concentrations in the serum. It specifically activates the C1C-2 chloride channels on the apical membrane of the intestinal epithelial cells. It increases intestinal fluid secretion to assist in GI motility, thereby decreasing the symptoms of constipation (eg, abdominal pain, bloating, straining, hard stools). It is approved to treat chronic idiopathic constipation; opioid-induced constipation in patients with chronic, noncancer pain; and for women with constipation caused by irritable bowel syndrome (IBS-C).

Linaclotide (Linzess)

GC-C agonist. Activation of GC-C receptors in the intestinal neurons leads to increased cyclic guanosine monophosphate (cGMP), anion secretion, fluid secretion, and intestinal transit. It appears to work topically rather than systemically. When administered PO, linaclotide activates chloride channels in intestinal epithelial cells to increase intestinal fluid secretion; it is indicated to treat chronic idiopathic constipation and for IBS-C in adults.

Plecanatide (Trulance)

GC-C agonist; plecanatide and its active metabolite bind to GC-C and act locally on the luminal surface of intestinal epithelial cells; GC-C activation leads to increased cyclic guanosine monophosphate (cGMP) activity, which, in turn, stimulates secretion of chloride and bicarbonate into the intestinal lumen, mainly by activation of the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel, resulting in increased intestinal fluid and accelerated transit; plecanatide is indicated for chronic idiopathic constipation in adults.


Laxatives, Osmotic

Class Summary

Osmotic agents are useful for long-term treatment of constipated patients with slow colonic transit that is refractory to dietary fiber supplementation.

Lactulose (Constulose, Enulose, Generlac, Kristalose)

Lactulose produces an osmotic effect in the colon, resulting in bowel distention and stimulation of peristalsis.


Sorbitol is a hyperosmotic laxative that has a cathartic action in the GI tract.

Polyethylene glycol solution (Miralax)

Polyethylene glycol is typically used in large volumes for bowel preparation and washout before surgical or endoscopic procedures. It is now being used in smaller volumes as an osmotic (but not hyperosmotic) agent.

In theory, there is a lower risk of dehydration or electrolyte imbalance with isotonic polyethylene glycol than with hypertonic sugar solutions. The laxative effect is generated because polyethylene glycol is not absorbed and continues to hold water by osmotic action throughout the small bowel and the colon, resulting in mechanical cleansing.

Lactitol (Pizensy)

Lactitol elicits an osmotic effect, causing influx of water into the small intestine, leading to a laxative effect in the colon. It is indicated for treatment of chronic idiopathic constipation in adults.


Stimulant Laxatives

Class Summary

Stimulant laxatives are commonly employed to treat acute constipation and are the most common class of laxatives used over the long term by individuals taking over-the-counter products. The latter represents an inappropriate choice, at least as first- or second-line therapy, given concerns about the development of tolerance.

Senna (Senokot, Ex-Lax, Senexon)

Sennosides induce defecation by acting directly on the intestinal mucosa or nerve plexus, which stimulates peristaltic activity, by increasing intestinal motility. Senna usually produces its action 8-12 hours after administration.

Bisacodyl (Bisac-Evac, Biscolax, Dulcolax, Dacodyl)

Bisacodyl stimulates peristalsis by possibly stimulating the colonic intramural neuronal plexus. It alters water and electrolyte secretion, resulting in net intestinal fluid accumulation and laxation. It provokes defecation within 24 hours and may cause abdominal cramping.

Castor oil

Castor oil is reduced to ricinoleic acid. It decreases net absorption of fluid and electrolytes and stimulates peristalsis. It acts on the small intestine.


Prokinetic Agents

Class Summary

Prokinetics are promotility agents proposed for use in patients with severe constipation-predominant symptoms.

Prucalopride (Motegrity)

Prucalopride, a selective 5-hydroxytryptamine (serotonin) type 4 receptor (5-HT4) agonist, is a gastrointestinal (GI) prokinetic agent that stimulates colonic peristalsis, thus increasing bowel motility. It is indicated for chronic idiopathic constipation.

Tegaserod (Zelnorm)

Tegaserod is available in the United States only by an emergency treatment investigational new drug (IND) protocol. This can be obtained from the FDA for irritable bowel syndrome (IBS) and IBS with constipation (IBS-C) or chronic idiopathic constipation (CIC) in women younger than 55 years who meet specific guidelines. The FDA Gastrointestinal Drugs Advisory Committee reviewed a supplemental new drug application (sNDA) for tegaserod in October 2018 with the proposed indication of treating women with IBS-C who do not have a history of cardiovascular (CV) ischemic disease. Their recommendation was to reintroduce tegaserod to the US market for women with IBS who are at low risk for CV ischemic disease.

Tegaserod is a serotonin type 4 (5-HT4) receptor partial agonist with no affinity for 5-HT3 receptors. It may trigger peristaltic reflex via 5-HT4 activation, which enhances basal motor activity and normalizes impaired GI motility.


Peripherally-Acting Mu-Opioid Receptor Antagonists

Class Summary

Peripherally acting mu-opioid receptor antagonists (PAMORAs) may provide relief from GI adverse effects such as constipation associated with chronic opioid use.

Methylnaltrexone (Relistor)

Methylnaltrexone is a PAMORA. It selectively displaces opioids from mu-opioid receptors outside the central nervous system (CNS), including those located in the GI tract, thereby decreasing the constipating effects of opioids. It is indicated for opioid-induced constipation in patients with advanced illness receiving palliative care when response to laxatives has not been sufficient. It is also indicated for opioid-induced constipation in patients with chronic noncancer pain who are treated with opioids. It is available as an injectable solution for subcutaneous use.

Naloxegol (Movantik)

Naloxegol is a PAMORA indicated for opioid-induced constipation in adults with chronic noncancer pain. Antagonism of gastrointestinal mu-opioid receptors by naloxegol inhibits the opioid-induced delay of GI transit time.

Alvimopan (Entereg)

Alvimopan is a peripherally acting mu-opioid receptor antagonist. It binds mu-opioid receptors in the gut, thereby selectively inhibiting the negative opioid effects on GI function and motility. It is indicated for postoperative ileus after bowel resection with primary anastomosis.

In 5 clinical studies that enrolled more than 2500 patients, alvimopan demonstrated accelerated recovery time of upper and lower tract GI function compared with placebo. A decrease in the hospital days was also observed in the alvimopan group.

Alvimopan is only available to hospitals after they complete a registration process designed to maintain the benefits associated with short-term use and prevent long-term outpatient use (Entereg Access Support and Education [EASE] program).

Naldemedine (Symproic)

Opioid antagonist with binding affinities for mu-, delta-, and kappa-opioid receptors. Naldemedine is a derivative of naltrexone to which a side chain has been added that increases the molecular weight and the polar surface area, thereby reducing its ability to cross the blood-brain barrier. It is indicated for opioid-induced constipation in adults with noncancer pain.