What are the treatment options for constipation?

Treatment Options for Constipation

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

Initial Assessment Before Treatment

Before initiating any therapy, perform a digital rectal examination to rule out fecal impaction and assess for bowel obstruction 2. Check corrected calcium levels and thyroid function if clinically indicated, as metabolic causes like hypercalcemia and hypothyroidism commonly contribute to constipation 2, 1. Review all medications and discontinue constipating agents when possible 2.

First-Line Pharmacological Treatment

Stimulant Laxatives (Preferred Initial Option)

• Senna: 2 tablets twice daily, best taken in the evening for morning effect 2, 1
• Bisacodyl: 10-15 mg daily, can be increased to 2-3 times daily if needed 2, 1, 3

The National Comprehensive Cancer Network guidelines emphasize that adding stool softeners like docusate to stimulant laxatives provides no additional benefit and should be avoided 1. This is a critical pitfall—many clinicians reflexively add docusate, but evidence shows it's ineffective when combined with stimulants 1.

Alternative First-Line: Osmotic Laxatives

If stimulants are not tolerated or preferred, osmotic laxatives are equally acceptable first-line options 2:

• Polyethylene glycol (PEG): 17g in 8 oz water once or twice daily—has excellent safety profile with virtually no electrolyte disturbances 2, 3
• Lactulose: Takes 2-3 days for effect; common side effects include sweet taste intolerance, nausea, and bloating 2
• Magnesium salts: Use cautiously in renal impairment due to hypermagnesemia risk 2, 3

Supportive Non-Pharmacological Measures

Implement these concurrently with laxatives 2:

• Ensure privacy and proper positioning (small footstool to assist gravity) 2
• Increase fluid intake to at least 2 liters daily if using fiber 1
• Increase physical activity within patient's limitations (even bed-to-chair transfers help) 2
• Schedule toileting attempts 30 minutes after meals, no more than 5 minutes of straining 2

Critical caveat: Dietary fiber and bulk laxatives like psyllium are not recommended for medication-induced constipation and require adequate hydration (≥2L daily) to be effective 1. Without sufficient fluid intake, fiber can worsen obstruction 3.

Second-Line Treatment for Persistent Constipation

If first-line therapy fails after adequate trial, add or switch to alternative osmotic or stimulant laxatives 1:

• Add PEG if started with stimulant 1, 3
• Add magnesium hydroxide or magnesium citrate (avoid in renal impairment) 1, 3
• Increase bisacodyl frequency to 2-3 times daily 1, 3
• Consider rectal bisacodyl suppository 10mg 2, 3

Management of Fecal Impaction

When digital rectal exam identifies full rectum or impaction 2:

• First-line: Glycerin or bisacodyl suppositories 2, 3
• Second-line: Hyperosmotic saline enemas 2
• Refractory cases: Manual disimpaction with premedication (analgesic ± anxiolytic) 3

Important contraindications for enemas 2: neutropenia, thrombocytopenia, recent colorectal/gynecological surgery, recent anal trauma, severe colitis, toxic megacolon, undiagnosed abdominal pain, or recent pelvic radiotherapy.

Third-Line: Prokinetic Agents

If gastroparesis is suspected (particularly relevant with GLP-1 agonists that slow gastric emptying), add metoclopramide 10-20 mg 2-3 times daily 1, 4.

Fourth-Line: Secretagogues

For persistent constipation unresponsive to standard laxatives, consider newer agents 1:

• Linaclotide: FDA-approved for IBS-C (290 mcg daily) and CIC (145 mcg daily); improves CSBM frequency, stool consistency, and straining 5
• Lubiprostone 1, 6
• Plecanatide 1

These agents are significantly more expensive but effective when conventional therapy fails 6.

Special Considerations

Opioid-Induced Constipation

• Prophylactic laxative required with first opioid dose 2
• Prefer osmotic or stimulant laxatives; avoid bulk laxatives 2
• Consider combined opioid/naloxone formulations 2
• For refractory cases: methylnaltrexone 0.15 mg/kg subcutaneously every other day (contraindicated in mechanical obstruction or postoperative ileus) 3, 4

Elderly Patients

• PEG 17g daily offers best safety profile 2
• Monitor closely if on diuretics or cardiac glycosides (dehydration/electrolyte risk) 2
• Avoid liquid paraffin in bed-bound patients or those with swallowing disorders (aspiration pneumonia risk) 2
• Ensure toilet access, especially with decreased mobility 2

Neurogenic Constipation

Abdominal massage may provide additional benefit in patients with concomitant neurogenic problems like Parkinson's disease or multiple sclerosis, though evidence is limited 2.

Treatment Goals

Aim for one non-forced bowel movement every 1-2 days, not necessarily daily bowel movements 1, 3, 4. This is an important expectation-setting conversation with patients who often believe daily bowel movements are mandatory.