What is the appropriate treatment for an otherwise healthy adult presenting with acute constipation?

Treatment for Acute Constipation

For an otherwise healthy adult with acute constipation, start with a stimulant laxative such as bisacodyl (10-15 mg) or sodium picosulfate as first-line therapy, which can be used short-term (up to 4 weeks) or as rescue therapy. 1

First-Line Treatment Approach

Stimulant laxatives are the preferred initial treatment:

• Bisacodyl 10-15 mg orally is strongly recommended for acute constipation, with the option to use 2-3 times daily if needed 1
• Sodium picosulfate is an equally effective alternative stimulant laxative 1
• These agents work rapidly and are ideal for occasional use or rescue therapy 1
• The goal is to achieve one non-forced bowel movement every 1-2 days 1

Alternative First-Line Options

If stimulant laxatives are not preferred or tolerated:

• Polyethylene glycol (PEG) 17 grams mixed with 8 oz of water twice daily is strongly recommended with moderate-quality evidence 1, 2
• PEG can be used alone or in combination with other agents 1
• Side effects include abdominal distension, loose stool, flatulence, and nausea 1

Magnesium-based osmotic laxatives:

• Magnesium citrate 8 oz (240 mL) once daily or magnesium oxide can be effective 1, 3
• Critical contraindication: Avoid in patients with renal insufficiency (creatinine clearance <20 mL/min) due to risk of fatal hypermagnesemia 2, 3
• Must rule out bowel obstruction before use 3

Supportive Measures

Hydration and dietary modifications:

• Maintain adequate fluid intake (≥1.5 L/day), guided by thirst 1
• Hot and cold beverages in variety can help; avoid carbonated drinks 1
• Increase consumption of fruits, vegetables, and whole grains 1, 4
• Important caveat: Supplemental fiber (like psyllium) is NOT recommended for acute constipation and may worsen symptoms 1

When to Escalate Treatment

If constipation persists after 24-48 hours:

• Reassess to rule out impaction or mechanical bowel obstruction 1, 3
• Consider adding a second osmotic laxative such as lactulose 30-60 mL twice daily or sorbitol 1, 3
• Rectal interventions (bisacodyl suppository 10 mg or glycerin suppository) can provide rapid relief 1
• Enemas (sodium phosphate, saline, or tap water) may be used sparingly 1

Critical Safety Warnings

Absolute contraindications to assess before treatment:

• Mechanical bowel obstruction must be ruled out clinically (and with imaging if indicated) before any laxative use 3
• Severe renal impairment contraindicates magnesium-based products 2, 3
• Avoid rectal suppositories/enemas in patients with neutropenia or thrombocytopenia 1
• Sodium phosphate products should be limited in patients at risk for renal dysfunction 1

Common Pitfalls to Avoid

Do NOT use docusate (stool softener) alone:

• Evidence shows docusate provides no benefit when added to stimulant laxatives and is not recommended 1

Do NOT start with fiber supplements:

• Medicinal fiber (psyllium, bran) is ineffective for acute constipation and may worsen symptoms 1
• Fiber is only appropriate for chronic constipation in patients with low dietary fiber intake 1

Do NOT delay treatment waiting for dietary changes:

• While dietary modifications are supportive, acute constipation requires pharmacological intervention for prompt relief 1