What is the best approach to manage constipation in an older adult?

Management of Constipation in Older Adults

Polyethylene glycol (PEG) 17 g/day is the first-line pharmacological treatment for constipation in older adults due to its superior efficacy and excellent safety profile. 1, 2

Initial Non-Pharmacological Interventions

Before initiating any medication, implement these specific measures:

• Ensure toilet access, particularly critical for patients with decreased mobility—this addresses a major barrier in elderly patients who may avoid defecation due to difficulty reaching facilities 1, 2

• Optimize toileting habits: Educate patients to attempt defecation twice daily, specifically 30 minutes after meals when the gastrocolic reflex is strongest, and instruct them to strain no more than 5 minutes 1, 2, 3

• Provide dietetic support and manage decreased food intake related to anorexia of aging or chewing difficulties, as reduced food volume directly affects stool consistency and bowel movements 1, 2

• Increase fluid intake to at least 1.5 liters daily, though this alone will not resolve constipation unless dehydration is present 3, 4

• Encourage physical activity within the patient's limitations, as even minimal movement from bed to chair stimulates bowel function 3, 5

First-Line Pharmacological Treatment

Start PEG 17 g/day dissolved in 4-8 ounces of water, juice, soda, coffee, or tea 1, 2, 6. This osmotic laxative works by retaining water in the stool, softening it and increasing bowel movement frequency 6. PEG is particularly appropriate for frail elderly patients because it does not require high fluid intake like bulk-forming agents 3.

The FDA label notes that 2-4 days may be required to produce a bowel movement, and the product should be used for 2 weeks or less unless directed by a physician 6. In geriatric nursing home patients, a higher incidence of diarrhea occurred at the 17 g dose—if this occurs, discontinue PEG 6.

Second-Line Options

If PEG is not tolerated or ineffective, proceed to:

• Osmotic alternatives: Lactulose 15-30 mL daily 2, 3
• Stimulant laxatives: Senna, bisacodyl, or sodium picosulfate (use with awareness of potential cramping and pain) 1, 2, 3

Docusate should be reserved only for very specific situations where other options are contraindicated or unavailable, as it is ineffective for both prevention and treatment of constipation in the elderly 2, 3.

Critical Safety Considerations

Medications to AVOID:

• Bulk-forming laxatives (psyllium, methylcellulose, polycarbophil) in non-ambulatory patients with low fluid intake—these significantly increase the risk of mechanical obstruction 1, 2, 3, 5

• Liquid paraffin in bed-bound patients or those with swallowing disorders due to risk of aspiration lipoid pneumonia 1, 2, 7

• Magnesium-containing laxatives (magnesium hydroxide) should be used with extreme caution due to hypermagnesemia risk, particularly in patients with renal impairment 1, 2, 7

• Sodium phosphate enemas—use isotonic saline enemas instead due to risks of hyperphosphatemia, electrolyte disturbances, cardiac complications, and death in elderly patients 1, 3, 7

Monitoring Requirements:

Regular monitoring is essential for patients with chronic kidney or heart failure, especially those on diuretics or cardiac glycosides, due to risks of dehydration and electrolyte imbalances 1, 2, 3.

Management of Fecal Impaction

For patients presenting with fecal impaction:

1. Manual disimpaction through digital fragmentation and extraction of stool 3
2. Follow with water or oil retention enemas or suppositories 3
3. Implement maintenance regimen with PEG 17 g/day to prevent recurrence 3

For patients with swallowing difficulties or repeated fecal impaction, rectal measures (enemas and suppositories) become the preferred ongoing treatment rather than oral agents 1, 2, 3, 7. Use isotonic saline enemas at volumes of 500-1000 mL 7.

Common Pitfalls

The myth that constipation results from "autointoxication" or that increasing fiber and fluids universally helps is not evidence-based 4. Many patients with severe constipation actually worsen with increased fiber 4. Similarly, fluid intake beyond treating dehydration does not resolve constipation 4.

Long-term use of stimulant laxatives at recommended doses does not damage the colon, and tolerance is uncommon—there is no evidence for "rebound constipation" after stopping laxatives 4. However, prolonged or excessive use of any laxative may result in electrolyte imbalance and dependence 6.