What are the treatment options for constipation?

Treatment of Constipation

Start with a stimulant laxative (senna or bisacodyl 10-15 mg, 2-3 times daily) as first-line therapy, aiming for one non-forced bowel movement every 1-2 days. 1

Initial Assessment

Before initiating treatment, perform a focused evaluation:

• Conduct an abdominal examination, perineal inspection, and digital rectal examination to identify fecal impaction or rectal loading 2, 3
• Rule out metabolic causes: Check corrected calcium (hypercalcemia), potassium (hypokalemia), thyroid function (hypothyroidism), and consider diabetes mellitus 1, 3
• Exclude bowel obstruction: Plain abdominal X-ray can image fecal loading extent and rule out obstruction 2, 3
• Review medications: Discontinue non-essential constipating drugs 3

Stepwise Treatment Algorithm

First-Line: Stimulant Laxatives

Begin with senna or bisacodyl 10-15 mg, 2-3 times daily 1. This is the National Comprehensive Cancer Network's recommended starting point, supported by strong evidence for efficacy 1.

Critical pitfall to avoid: Do NOT add stool softeners like docusate to stimulant laxatives—evidence demonstrates no additional benefit 1.

Second-Line: Add Osmotic or Additional Stimulant Laxatives

If constipation persists after first-line therapy, add one of the following 1, 3:

• Polyethylene glycol (PEG) - preferred option with excellent safety profile, particularly in elderly patients (17 g/day) 2, 3
• Lactulose 2, 1, 3
• Magnesium hydroxide or magnesium citrate - use cautiously in renal impairment due to hypermagnesemia risk 2
• Rectal bisacodyl 1

Third-Line: Prokinetic Agents

If gastroparesis is suspected, add metoclopramide 10-20 mg, 2-3 times daily 1. This is particularly relevant for patients on GLP-1 agonists that slow gastric emptying 1.

Fourth-Line: Secretagogues

For persistent constipation unresponsive to standard laxatives, consider intestinal secretagogues: linaclotide, lubiprostone, or plecanatide 1, 4, 5.

Non-Pharmacological Measures

Implement these alongside pharmacological treatment 2, 3:

• Ensure privacy and comfort for normal defecation 2, 3
• Optimize positioning: Use a small footstool to facilitate pressure application 2, 3
• Increase fluid intake (at least 2 liters daily if using fiber) 1, 3
• Increase physical activity and mobility within patient limits, even bed-to-chair transfers 2, 3
• Abdominal massage may reduce gastrointestinal symptoms, particularly in patients with neurogenic problems 2, 3

Special Considerations

Dietary Fiber - Important Limitations

Do NOT rely on fiber supplements for medication-induced constipation 1. Fiber (psyllium, methylcellulose) is ineffective for drug-induced constipation and requires adequate hydration (≥2 liters daily) to work 1. Bulk laxatives like psyllium are specifically NOT recommended for opioid-induced constipation 2. While fiber supplementation can improve stool frequency and consistency in primary constipation, particularly psyllium and pectin at doses >10 g/day for ≥4 weeks 6, this is not the appropriate first-line approach for most constipation cases.

Opioid-Induced Constipation

All patients receiving opioid analgesics should be prescribed a concomitant laxative unless contraindicated by pre-existing diarrhea 2, 3. Start with osmotic or stimulant laxatives 2. For unresolved opioid-induced constipation, peripherally acting μ-opioid receptor antagonists (PAMORAs) like methylnaltrexone 0.15 mg/kg subcutaneously every 2 days may be used 2, 3, 4, 5.

Fecal Impaction

When digital rectal examination identifies a full rectum or fecal impaction, suppositories and enemas are preferred first-line therapy 2. Best practice involves digital fragmentation and extraction of stool, followed by maintenance bowel regimen to prevent recurrence 2, 3.

Contraindications for enemas: neutropenia, thrombocytopenia, paralytic ileus, intestinal obstruction, recent colorectal/gynecological surgery, recent anal/rectal trauma, severe colitis, abdominal inflammation/infection, toxic megacolon, undiagnosed abdominal pain, or recent pelvic radiotherapy 2.

Elderly Patients

Pay particular attention to elderly patient assessment 2, 3:

• Ensure toilet access, especially with decreased mobility 2
• Provide dietetic support and manage decreased food intake 2
• Optimize toileting: Educate patients to attempt defecation twice daily, 30 minutes after meals, straining no more than 5 minutes 2
• PEG (17 g/day) offers the best safety profile for elderly patients 2, 3
• Avoid liquid paraffin in bedridden patients and those with swallowing disorders due to aspiration lipoid pneumonia risk 2, 3
• Monitor for dehydration and electrolyte imbalances when using diuretics or cardiac glycosides concomitantly 2, 3

Treatment Goals

Aim for one non-forced bowel movement every 1-2 days, not necessarily daily bowel movements 1. Reassess for impaction or obstruction if constipation persists despite treatment 1.