Management of Constipation in Elderly Patients
Start with polyethylene glycol (PEG) 17 g/day as first-line pharmacological treatment after implementing non-pharmacological measures, as it offers the best efficacy and safety profile in elderly patients with multiple comorbidities and polypharmacy. 1, 2
Initial Assessment
Before prescribing any laxative, perform a digital rectal examination to rule out fecal impaction, which requires immediate manual disimpaction rather than oral laxatives. 3, 4 If impaction is present, proceed directly to manual fragmentation and extraction followed by enemas, then start maintenance PEG therapy. 3
Review all current medications systematically, as polypharmacy is a major contributor to constipation in elderly patients—look specifically for anticholinergics, opioids, calcium channel blockers, iron supplements, and diuretics. 5
Non-Pharmacological Measures (Implement First)
Ensure toilet access is readily available, particularly critical for patients with decreased mobility who may develop constipation simply from inability to reach facilities in time. 1, 2
Optimize toileting habits by educating 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 to avoid pelvic floor dysfunction. 1, 2
Provide dietetic support to manage decreased food intake related to anorexia of aging or chewing difficulties, as reduced food volume directly decreases stool bulk and consistency. 1
Increase fluid intake to at least 1.5 liters daily, though recognize this may be challenging in frail elderly patients. 3, 6
Pharmacological Treatment Algorithm
First-Line: Polyethylene Glycol (PEG)
PEG 17 g/day is the preferred initial laxative because it has demonstrated efficacy with an excellent safety profile, does not cause electrolyte imbalances, and does not require high fluid intake like bulk-forming agents. 1, 2, 3 This is particularly important in frail elderly patients who cannot maintain adequate hydration. 3, 7
Second-Line: Osmotic or Stimulant Laxatives
If PEG is not tolerated or ineffective after an adequate trial, switch to:
Lactulose 15-30 mL daily as an osmotic alternative, though it may cause bloating and flatulence. 2, 3, 8
Stimulant laxatives (senna, bisacodyl, sodium picosulfate) can be used, though be cognizant of risks for abdominal cramping and pain. 1, 2
What to Avoid
Do not prescribe bulk-forming laxatives (psyllium, methylcellulose, polycarbophil) to non-ambulatory elderly patients with low fluid intake because they significantly increase the risk of mechanical bowel obstruction. 1, 2, 3 This is a critical safety concern in frail, bed-bound patients. 7
Avoid liquid paraffin in bed-bound patients and those with swallowing disorders due to the serious risk of aspiration lipoid pneumonia. 1, 2
Use magnesium-containing laxatives (magnesium hydroxide) with extreme caution in elderly patients, particularly those with any degree of renal impairment, due to risk of life-threatening hypermagnesemia. 1, 2, 6
Docusate should be reserved only for very specific situations where other options are contraindicated, as it is largely ineffective for both prevention and treatment of constipation in the elderly. 2, 3
Special Considerations for Cardiac and Renal Comorbidities
Laxative selection must be individualized based on cardiac and renal comorbidities, with particular attention to drug interactions. 1, 2
Monitor patients with chronic kidney or heart failure regularly when they are on concomitant diuretics or cardiac glycosides, as laxatives can exacerbate dehydration and electrolyte imbalances. 1
Management of Fecal Impaction
For patients presenting with fecal impaction (confirmed by digital rectal examination):
Perform manual disimpaction through digital fragmentation and extraction of stool as the first-line intervention, ensuring no suspected perforation or gastrointestinal bleeding exists. 3
Follow with water or oil retention enemas or suppositories to facilitate passage of remaining stool. 3
Start maintenance PEG 17 g/day immediately after disimpaction to prevent recurrence. 3
Rectal Measures for Specific Situations
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
Use isotonic saline enemas rather than sodium phosphate enemas in elderly patients due to the significant risk of electrolyte disturbances and potential adverse events with phosphate preparations. 1, 3
Common Pitfalls to Avoid
The most common error is prescribing laxatives without first performing a digital rectal examination—this leads to prescribing oral laxatives to patients with fecal impaction, which worsens the obstruction. 4
Another frequent mistake is continuing stool softeners or laxatives in patients who develop diarrhea or fecal incontinence, when these medications should be immediately discontinued. 4
Do not use sodium phosphate enemas in elderly patients due to electrolyte disturbance risk. 1, 3
Monitoring and Follow-Up
Regular monitoring for adverse effects is essential, particularly in patients with renal impairment who are at higher risk for electrolyte imbalances and medication toxicity. 2
Assess response to treatment by tracking bowel movement frequency and consistency, with the goal of achieving 2-3 soft stools daily. 8, 9