Macrogol (PEG 3350) — NZ Medication Guide

📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.

What is Macrogol (PEG 3350)?

Macrogol (polyethylene glycol 3350) is an osmotic laxative used for the treatment of constipation in adults and children. This medication is funded by Pharmac for constipation in adults and children.

What is Macrogol (PEG 3350) Used For?

Macrogol is used for the treatment of chronic constipation, faecal impaction (as a higher-dose disimpaction regimen), and as bowel preparation before colonoscopy.

How Does Macrogol (PEG 3350) Work?

Macrogol is an inert polymer that is not absorbed from the gastrointestinal tract. It retains water osmotically in the bowel lumen, softening stools and increasing stool volume — stimulating normal bowel peristalsis without causing electrolyte disturbance.

How to Take Macrogol (PEG 3350)

For constipation: one sachet (13.7 g macrogol 3350 in Lax-Sachets®) dissolved in 125 mL water, once or twice daily. For faecal impaction: 4–8 sachets per day over 3 days. For children: Movicol® Paediatric sachets are weight-dosed. Onset of action: 24–72 hours.

Common Side Effects of Macrogol (PEG 3350)

• Abdominal bloating and distension (common — settles over time)
• Flatulence
• Nausea
• Abdominal cramping

Serious Side Effects — Seek Medical Attention

Contact your doctor or call 111 immediately if you experience any of the following:

• Severe allergic reaction (rare)
• Aspiration (if patient unable to swallow safely — use with care in dysphagia)

Drug Interactions

Macrogol (PEG 3350) may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:

• May slow absorption of other medicines taken simultaneously — separate by 2 hours if possible

New Zealand Prescribing Information

Macrogol 3350 sachets (Lax-Sachets® 13.7 g; Movicol® Paediatric Plain sachets for children) are funded by Pharmac. Macrogol is the preferred osmotic laxative in NZ for chronic constipation in both adults and children, for opioid-induced constipation, and during pregnancy. Unlike stimulant laxatives, it does not cause dependence and is safe for long-term use.

Frequently Asked Questions

Is macrogol safe to use long-term?

Yes — macrogol is safe for long-term use and does not cause dependence. Unlike stimulant laxatives, it works by retaining water in the bowel rather than stimulating the bowel muscles. It is considered one of the safest laxatives for chronic constipation management.

How long does macrogol take to work?

Macrogol typically takes 24–72 hours to produce a bowel action. For faecal impaction (severe constipation), a high-dose disimpaction regimen over 3 days is used under medical supervision.

References & Further Information

The following New Zealand and international resources were used to inform this page. We encourage you to consult these authoritative sources for the most current information:

• New Zealand Formulary — Macrogol 3350
• Pharmac — Funded Medicines Schedule
• BPAC NZ — Managing Constipation in Adults

⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.

Reviewed by a Registered Pharmacist NZ