In an adult with chronic constipation, which is preferred: polyethylene glycol (PEG), lactulose, or Cremaffin (sodium picosulfate‑liquid paraffin‑magnesium hydroxide)?

PEG is the Best First-Line Treatment for Chronic Constipation

Polyethylene glycol (PEG) should be your first-line pharmacological choice for chronic constipation in adults, with lactulose reserved only for patients who fail or cannot tolerate PEG, and Cremaffin (sodium picosulfate combination) used short-term or as rescue therapy rather than for chronic daily management. 1

Evidence-Based Treatment Algorithm

First-Line: PEG (Strong Recommendation)

• PEG receives a STRONG recommendation with MODERATE certainty evidence from the 2023 AGA-ACG guidelines 1
• Start with 17g daily mixed in 8 ounces of liquid
• Efficacy proven durable over 6 months 1
• Increases complete spontaneous bowel movements by 2.9 per week compared to placebo 1
• More effective than lactulose with better tolerability 2, 3, 4

Why PEG wins: Meta-analyses consistently show PEG produces 1 additional stool per week compared to lactulose, with significantly less flatulence and bloating 2, 4. A 1999 study demonstrated PEG required lower doses (1.6 sachets/day) versus lactulose (2.1 sachets/day) for equivalent effect 3.

Second-Line: Lactulose (Conditional Recommendation)

• Use ONLY after PEG failure or intolerance 1
• Receives only a CONDITIONAL recommendation with VERY LOW certainty evidence 1
• Start 15g daily, titrate as needed 5
• Major limitation: dose-dependent bloating and flatulence that often limits clinical use 1

Cremaffin (Sodium Picosulfate Component): Short-Term/Rescue Only

• NOT recommended for chronic daily management 1
• The sodium picosulfate component receives a STRONG recommendation but explicitly for "short-term or rescue therapy" 1
• Short-term defined as ≤4 weeks daily use 1
• Long-term safety and efficacy data lacking 1
• Best used occasionally or in combination with other agents 1

Critical Clinical Distinctions

Strength of recommendations matters: The guidelines use "recommend" (strong) for PEG versus "suggest" (conditional) for lactulose—this reflects substantial differences in evidence quality 1. PEG has moderate certainty evidence while lactulose has very low certainty evidence 1.

The lactulose positioning is key: Guidelines explicitly state lactulose is for patients "who fail or are intolerant to OTC therapies" 1—it's not a co-equal first choice.

Common Pitfalls to Avoid

1. Don't start with lactulose: Despite its availability, the evidence hierarchy clearly favors PEG first 1, 2, 4

2. Don't use Cremaffin chronically: The stimulant component (sodium picosulfate) lacks long-term safety data and should not be used as daily maintenance therapy 1

3. Don't underdose PEG: The effective dose is 17g daily; patients often use insufficient amounts 1

4. Don't ignore side effect profiles: Lactulose's bloating/flatulence is dose-dependent and frequently causes discontinuation, while PEG's side effects (abdominal distension, loose stool) are generally milder 1

Practical Implementation

Start here: PEG 17g daily, can combine with fiber for mild constipation 1

If PEG fails or causes intolerable side effects: Switch to lactulose 15g daily, titrate upward 1, 5

For acute exacerbations: Add sodium picosulfate (Cremaffin component) as rescue, not maintenance 1

Renal insufficiency caveat: Avoid magnesium-containing products like the magnesium hydroxide in Cremaffin 1

The evidence is unambiguous: PEG's superior efficacy, better tolerability, proven durability, and stronger guideline support make it the clear winner for chronic constipation management 1, 2, 4.