What are the treatment options for constipation?

Treatment of Constipation

Start with osmotic laxatives (polyethylene glycol/PEG or lactulose) or stimulant laxatives (senna or bisacodyl) as first-line pharmacological therapy, as these are the preferred agents with the strongest evidence base. 1, 2

Initial Assessment Before Treatment

Before initiating any therapy, perform a digital rectal examination (DRE) to identify fecal impaction or a full rectum, as this changes your immediate management approach. 1 Check corrected calcium levels and thyroid function if clinically suspected, and obtain a plain abdominal X-ray if you need to image the extent of fecal loading or exclude bowel obstruction. 1

First-Line Non-Pharmacological Management

Implement these foundational measures alongside any pharmacological therapy:

• Ensure privacy and proper positioning during defecation—use a small footstool to assist gravity and allow easier straining (no more than 5 minutes). 1
• Increase fluid intake to support stool softening and laxative efficacy. 1
• Increase physical activity and mobility within the patient's limits, even just bed-to-chair transfers can help. 1
• Consider soluble fiber (psyllium/ispaghula) only if the patient can maintain adequate fluid intake of at least 2 liters daily—start at 3-4 g/day and increase gradually to avoid bloating. 2 Avoid insoluble fiber (wheat bran) as it can worsen symptoms. 2
• Do not rely on fiber supplements alone for medication-induced constipation, as they are ineffective without adequate hydration. 2

First-Line Pharmacological Treatment

Choose one of the following preferred laxatives:

Osmotic Laxatives (Strongly Endorsed)

• Polyethylene glycol (PEG/Macrogol): Preferred option with virtually no net gain or loss of sodium and potassium—strongly endorsed in systematic reviews. 1 Start at 17 g/day and titrate to effect. 1
• Lactulose: Not absorbed by the small bowel, with 2-3 day latency before effect—common side effects include sweet taste intolerance, nausea, and abdominal distention. 1
• Magnesium salts: Effective but use cautiously in renal impairment due to risk of hypermagnesemia. 1

Stimulant Laxatives

• Senna or bisacodyl: Start with 10-15 mg daily, can increase to 2-3 times daily if needed. 2 Best taken in the evening for a morning bowel movement. 1 Goal is one non-forced bowel movement every 1-2 days, not daily bowel movements. 2
• Sodium picosulfate: Works similarly to bisacodyl for short-term use in refractory constipation. 1

Critical pitfall: Do not add stool softeners (docusate) to stimulant laxatives—evidence shows no additional benefit. 2

Management of Fecal Impaction

If DRE identifies a full rectum or fecal impaction, suppositories and enemas are first-line therapy, not oral laxatives. 1

• Glycerine, bisacodyl, or CO2-releasing suppositories work as stool softeners and rectal stimulants. 1
• Hyperosmotic saline enemas increase water content and stimulate peristalsis, working faster than oral agents. 1
• After disimpaction, implement a maintenance bowel regimen to prevent recurrence. 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

Second-Line Treatment for Persistent Constipation

If first-line laxatives fail after adequate trial (typically 4-6 weeks), add or switch to:

• Additional osmotic or stimulant laxative from the options above if not already tried. 2
• Abdominal massage may provide additional benefit, particularly in patients with neurogenic problems (Parkinson's disease, multiple sclerosis), though evidence in general populations is limited. 1

Third-Line Treatment: Prokinetic Agents

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

Fourth-Line Treatment: Prescription Secretagogues

For constipation unresponsive to standard laxatives, consider newer agents:

• Linaclotide 145 mcg once daily (for chronic idiopathic constipation) or 290 mcg once daily (for IBS-C)—take on empty stomach at least 30 minutes before first meal. 2, 3 This is the most effective FDA-approved secretagogue with high-quality evidence. 2
• Lubiprostone or plecanatide as alternatives if linaclotide not tolerated. 2
• Review efficacy after 3 months and discontinue if no response. 2

Special Considerations for Opioid-Induced Constipation

All patients receiving opioid analgesics should be prescribed a concomitant laxative prophylactically unless contraindicated by pre-existing diarrhea. 1 Osmotic or stimulant laxatives are preferred first-line. 1 Bulk laxatives (psyllium) are not recommended for opioid-induced constipation. 1

For unresolved opioid-induced constipation, consider:

• Combined opioid/naloxone medications to reduce OIC risk. 1
• Peripherally acting mu-opioid receptor antagonists (PAMORAs) as targeted therapy, though expensive. 1, 4

Elderly Patient Considerations

Pay particular attention to assessment in elderly patients:

• Ensure toilet access, especially with decreased mobility. 1
• Provide dietetic support and manage decreased food intake (anorexia of aging, chewing difficulties). 1
• PEG 17 g/day offers efficacy with good safety profile in elderly patients. 1
• Avoid liquid paraffin in bed-bound patients or those with swallowing disorders due to aspiration pneumonia risk. 1
• Monitor for dehydration and electrolyte imbalances when diuretics or cardiac glycosides are co-prescribed. 1
• Use magnesium salts cautiously due to limited evidence in older adults and renal concerns. 1

What NOT to Do: Critical Pitfalls

• Do not use bulk laxatives alone for medication-induced constipation—they require high fluid volume and efficacy wanes over time. 1, 2
• Do not continue docusate (stool softeners) as evidence demonstrates lack of efficacy. 2
• Do not prescribe fiber without ensuring adequate fluid intake (at least 2 liters daily). 2
• Do not use magnesium-based laxatives long-term without monitoring for toxicity, especially in renal impairment. 1, 4