Background – It is not fun to have or to treat constipation. Constipation has been defined as fewer than three bowel movements per week with straining, passing of hard stools, or incomplete evacuation. It is especially common in older adults, women, and patients with serious illness. It can lead to complications such as hemorrhoids, fissures, or impaction. As with other symptoms, rational therapy should be based on a sound understanding of underlying physiology. The management goal is not cure, but restoration of a comfortable, predictable bowel routine that enhances quality of life.

Solid waste –  Too much or too little is a problem. The intestine is most efficient pushing intermediate volumes. Adequate dietary fiber increases stool bulk and stimulates peristalsis. Adults should aim for about 25 g/day (women) and 38 g/day (men). Psyllium, methylcellulose, and calcium polycarbophil are first-line bulk-forming agents. However, in patients with advanced illness, immobility, poor fluid intake (end of life), or on opioid therapy, added fiber can worsen constipation or cause impaction; in these cases, avoid bulk-forming laxatives.

Water content – Stool water content depends on how much water we drink, our general hydration status, how much water is absorbed from and secreted into the intestine and how fast stool moves through the bowel. Any of these variables can be manipulated. It is easiest to limit absorption (and increase secretion into the gut) by adding osmotically active particles that retain water (e.g. Magnesium salts, non-absorbable sugars such as sorbitol and lactulose, or polyethylene glycol [PEG]). Polyethylene glycol (PEG 3350) is the preferred osmotic laxative due to strong efficacy and safety data. It produces effect within 1-3 days and is flavorless and well tolerated. Lactulose and sorbitol remain alternatives but cause bloating/cramping and some cannot tolerate the syrupy taste. Magnesium and phosphate-based products act faster but should be avoided in renal impairment, frail elderly, or heart failure due to electrolyte risk. Note: hyperosmolar solutions may worsen dehydration by drawing body water into the gut lumen.

Motility –  Patients with low-activity levels (bed-ridden, dying patients and patients with advanced neurodegenerative disorders) and use of certain drugs (see below) lead to motility problems. Stimulant laxatives (senna, bisacodyl) increase colonic peristalsis and secretion. They are first-line for opioid-induced constipation (OIC) and effective in immobile or advanced illness patients. Senna preparations, which stimulate the myenteric plexus are generally favored. Senna can be titrated to up to 4 tablets twice daily depending upon patient need.  There is no evidence that senna must be combined with docusate for OIC and combination products combining both senna and docusate are typically much more expensive. Bisacodyl acts within 6-10 hours orally or 15-60 minutes rectally. Stimulants are safe for chronic use in OIC, despite prior concerns about long-term harm.

Lubrication eases passage and minimizes pain that can interfere with excretion. Most used is dioctyl sodium sulfosuccinate (DSS, or docusate), which decreases stool surface tension much like soap. Usual dosage is 240 mg PO daily or BID. DSS also tastes like soap, so liquid DSS should never be given PO, but may be given to tube-fed patients. Docusate is not effective alone for prevention or treatment of OIC and should only be used with stimulants when softer stools are desired (e.g., anal fissures, painful hemorrhoids). Mineral oil is discouraged due to aspiration risk and interference with fat-soluble vitamin absorption. Glycerin suppositories remain an option for rectal softening and quick relief. 

 Opioid-Induced Constipation (OIC) – Constipation due to opioids does not improve with tolerance and requires pharmacologic prophylaxis. Nearly all patients on chronic opioids should receive a stimulant laxative (senna or bisacodyl) ± PEG at opioid initiation. Docusate alone is ineffective. For refractory OIC, peripherally acting µ-opioid receptor antagonists (PAMORAs) such as methylnaltrexone, naloxegol, or naldemedine can be considered. See Fast Fact #294 and Fast Fact #295 for more information on OIC.

Special Populations – Older adults: Higher prevalence; PEG or stimulants preferred. Avoid mineral oil and sodium phosphate enemas. Pregnancy/lactation: First line is lifestyle and fiber; PEG and docusate are safe. Avoid castor oil, mineral oil, and saline laxatives. Children: Glycerin suppositories or oral docusate safe; PEG is often used off-label. Avoid Epsom salt and castor oil.

Medications that can cause/exacerbate constipation – Culprits include opioids, anticholinergics, calcium channel blockers (esp. verapamil), iron, calcium supplements, antihistamines, antidepressants (TCAs, bupropion), anticonvulsants (carbamazepine, valproate), antineoplastics (vinca alkaloids), and antiemetics (ondansetron). Review medications with a clinical pharmacist and deprescribe when possible.

References 

1. Klaschik E, Nauck F, Ostgathe C. Constipation–modern laxative therapy. Support Care Cancer. 2003; 11(11):679-685.
2. Mancini I, Bruera E. Constipation in advanced cancer patients. Support Care Cancer. 1998; 6(4):356-364.
3. Leung L, Riutta T, Kotecha J, Rosser W. Chronic constipation: an evidence-based review. J Am Board Fam Med. 2011;24(4):436-451. doi:10.3122/jabfm.2011.04.100272.
4. World Gastroenterology Organisation. WGO practice guideline: Constipation. Available at: www.worldgastroenterology.org/guidelines/constipation. Accessed February 1, 2023. 

Version History:  2nd Edition published August 2005; 3rd Edition May 2015; 4th Edition in January 2026.
Conflicts of Interest: None to report.