How to manage constipation in a patient?

Managing Constipation: A Practical Approach

Start with a stimulant laxative (senna or bisacodyl) with or without polyethylene glycol (PEG), aiming for one non-forced bowel movement every 1-2 days. 1

Initial Assessment

Before treating, quickly rule out serious causes:

• Check for fecal impaction via digital rectal exam—if present, manual disimpaction is required first 1, 2
• Rule out bowel obstruction—abdominal exam, assess for distension, severe pain 1
• Review medications—opioids, anticholinergics, antacids are common culprits 1
• Look for red flags—rectal bleeding, unintentional weight loss, new onset in elderly without clear cause 3, 4

Yes, constipation can absolutely make patients feel sick—it causes physical discomfort, abdominal pain, nausea, and psychological distress. 1

First-Line Treatment Algorithm

Step 1: Start Laxatives Immediately

For most patients:

• Senna 8.6-17.2 mg twice daily OR bisacodyl 10-15 mg 2-3 times daily 1
• Can add PEG 17 g daily (mix with 8 oz water) for additional effect 1, 5

For elderly patients specifically:

• PEG 17 g/day is the preferred first choice due to excellent safety profile and efficacy 1, 5, 2

Critical point: Docusate (stool softener) alone is ineffective—one study showed senna alone worked better than senna plus docusate. 1, 6 If using a stool softener, it must be combined with a stimulant, not used alone. 1

Step 2: Add Lifestyle Measures (But Don't Wait for These)

• Increase fluid intake to at least 1.5 liters daily 2
• Encourage physical activity within patient's ability 1, 2
• Optimize toileting: attempt defecation 30 minutes after meals, twice daily, strain no more than 5 minutes 1, 5, 2

Important caveat: Don't assume fiber or fluids will fix constipation—many patients with severe constipation worsen with increased fiber, and there's no evidence that increasing fluids helps unless the patient is dehydrated. 7, 8 Bulk-forming laxatives like psyllium are ineffective for opioid-induced constipation. 1

If Constipation Persists After 2-3 Days

Step 3: Escalate Treatment

Add or switch to:

• Lactulose 15-30 mL daily (osmotic laxative) 1, 2
• Magnesium hydroxide or citrate for faster effect 1—but use cautiously in elderly or those with renal impairment due to hypermagnesemia risk 1, 5
• Increase PEG dose if already using it 1

For rectal interventions:

• Bisacodyl suppository 10 mg once daily 1
• Glycerin suppositories for mild impaction 1
• Fleet, saline, or tap water enema 1—but use isotonic saline in elderly, not sodium phosphate 1, 2

Step 4: Consider Prokinetic Agents

If gastroparesis suspected (early satiety, bloating, nausea):

• Metoclopramide 10 mg three times daily 1—but limit chronic use due to tardive dyskinesia risk 1

Special Situation: Opioid-Induced Constipation

Prophylaxis is mandatory:

• Start stimulant laxative (senna or bisacodyl) with or without PEG at the same time opioids are initiated 1
• Patients do not develop tolerance to opioid-induced constipation 1

If standard laxatives fail:

• Methylnaltrexone 0.15 mg/kg subcutaneously every other day (peripherally-acting opioid antagonist) 1
• Naloxegol is another option 1
• Consider opioid rotation to fentanyl or methadone 1

Managing Fecal Impaction

If digital rectal exam reveals impaction:

1. Manual disimpaction first—digital fragmentation and extraction 1, 2
2. Follow with enema (water or oil retention) or suppositories 2
3. Then start maintenance PEG 17 g/day to prevent recurrence 2

Contraindications to enemas: neutropenia, thrombocytopenia, recent pelvic surgery or radiation, severe colitis, undiagnosed abdominal pain 1

Critical Pitfalls to Avoid

• Don't use bulk-forming laxatives (psyllium) in non-ambulatory patients or those with low fluid intake—risk of mechanical obstruction 1, 5, 2
• Don't use liquid paraffin in bed-bound patients or those with swallowing disorders—aspiration pneumonia risk 1, 5
• Don't rely on docusate alone—it's ineffective 1, 2, 6
• Don't assume laxatives are harmful or cause dependence—this is a myth; stimulant laxatives at recommended doses are safe long-term 7
• Don't wait more than 7 days without a bowel movement—seek further evaluation 3

When to Refer or Investigate Further

Refer to gastroenterology if:

• No response to multiple laxative trials after 1-2 weeks 9, 10, 8
• Suspected defecatory disorder (excessive straining, sense of blockage, need for digital maneuvers) 10, 8
• Need for anorectal manometry or colonic transit studies 9, 8

Red flags requiring urgent evaluation:

• Rectal bleeding 3, 4
• Severe abdominal pain, distension 1
• Nausea, vomiting, inability to pass gas (possible obstruction) 4