What are the treatment options for constipation?

Treatment Options for Constipation

Start with osmotic laxatives (polyethylene glycol or lactulose) or stimulant laxatives (senna or bisacodyl) as first-line pharmacological therapy, combined with non-pharmacological measures including increased fluid intake and physical activity. 1, 2

Initial Assessment

Before initiating treatment, evaluate for reversible causes and severity:

• Assess for treatable causes: hypercalcemia, hypokalemia, hypothyroidism, diabetes mellitus, and medication-induced constipation 1
• Perform physical examination: abdominal examination, perineal inspection, and digital rectal examination to identify impaction or obstruction 1, 2
• Check labs if clinically indicated: corrected calcium and thyroid function 1, 2
• Consider plain abdominal X-ray to evaluate fecal loading extent and exclude bowel obstruction 1, 2

Non-Pharmacological Management (First-Line for All Patients)

• Increase fluid intake to adequate levels 1, 2
• Increase physical activity and mobility within patient's capabilities, even bed-to-chair transfers 1, 2
• Optimize toileting conditions: ensure privacy, comfort, and proper positioning (small footstool can facilitate defecation) 1, 2
• Add dietary fiber (25 g/day) only if fluid intake is adequate; fiber is effective for simple constipation but evidence for pain reduction is mixed 1, 2, 3
• Consider abdominal massage particularly for patients with neurogenic problems 1, 2

Important caveat: Bulk laxatives like psyllium are NOT recommended for opioid-induced constipation 1 and compounds like Metamucil are unlikely to control opioid-induced constipation 1

Pharmacological Treatment Algorithm

Step 1: First-Line Laxatives

Osmotic laxatives (preferred):

• Polyethylene glycol (PEG) 1, 2
• Lactulose 30-60 mL daily 1, 2
• Magnesium hydroxide 30-60 mL daily or magnesium citrate 1

OR Stimulant laxatives:

• Senna (docusate combination: 2 tablets every morning, maximum 8-12 tablets per day) 1, 2
• Bisacodyl 10-15 mg, 2-3 times daily 1, 2
• Sodium picosulfate 1, 2

Treatment goal: One non-forced bowel movement every 1-2 days 1

Caution: Magnesium salts can cause hypermagnesemia; use cautiously in renal impairment 1, 2

Step 2: If Constipation Persists

• Reassess for obstruction and impaction 1
• Add additional laxative agents from different classes 1
• Consider prokinetic agent (metoclopramide 10-20 mg PO 3-4 times daily) if gastroparesis suspected 1

Step 3: For Fecal Impaction

• Glycerine suppositories or bisacodyl suppository daily 1
• Manual disimpaction (digital fragmentation and extraction) 1, 2
• Fleet, saline, or tap water enema 1

Contraindications for enemas: neutropenia, thrombocytopenia, paralytic ileus, intestinal obstruction, recent colorectal/gynecological surgery, recent anal/rectal trauma, severe colitis, toxic megacolon, undiagnosed abdominal pain, or recent pelvic radiotherapy 1

Opioid-Induced Constipation (Special Considerations)

• Prophylactic laxatives are mandatory when starting opioids (unless pre-existing diarrhea) 1, 2
• Increase laxative dose when increasing opioid dose 1
• Avoid bulk laxatives like psyllium for opioid-induced constipation 1

If Standard Laxatives Fail:

Peripherally-acting μ-opioid receptor antagonists (PAMORAs):

• Methylnaltrexone 0.15 mg/kg subcutaneously every other day (maximum once daily) for opioid-induced constipation unresponsive to standard therapy 1, 2
• Contraindications: postoperative ileus or mechanical bowel obstruction 1
• Naloxegol is another option for chronic opioid use 1

Alternative agents:

• Lubiprostone (prostaglandin analog) effective for opioid-induced constipation in chronic non-cancer pain 1
• Linaclotide (guanylate cyclase-C agonist) effective for IBS-associated and chronic idiopathic constipation 1

Special Populations

Elderly Patients

• Pay particular attention to assessment 1, 2
• Ensure toilet access especially with decreased mobility 1, 2
• Provide dietetic support and manage decreased food intake 1, 2
• Optimize toileting: attempt defecation twice daily, 30 minutes after meals, strain no more than 5 minutes 1, 2
• PEG 17 g/day is safe and effective 2
• Avoid liquid paraffin in bedridden patients or those with swallowing disorders due to aspiration risk and lipoid pneumonia 2

Cancer Patients

• Constipation affects approximately 50% of advanced cancer patients 2
• Discontinue non-essential constipating medications 2
• Monitor for electrolyte imbalances when using diuretics or cardiac glycosides concomitantly 2

Key Clinical Pitfalls

• Do not rely on fiber alone for opioid-induced constipation—it is ineffective 1
• Higher fiber doses (>10 g/day) and longer treatment duration (≥4 weeks) are needed for effectiveness in chronic constipation 3
• Psyllium and pectin are the most effective fiber types when fiber is appropriate 3
• Always rule out obstruction before escalating laxative therapy 1
• Individualize laxative choice based on cardiac/renal comorbidities and medication interactions 2