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Osmotic Laxative Pregnancy: Compatible — macrogol not absorbed; preferred osmotic laxative in pregnancy after lactulose.

Macrogol (Polyethylene Glycol)

Brand names: Movicol, Laxido, CosmoCol

Adult dose

Dose: Constipation: 1–3 sachets dissolved in 125mL water each, taken daily (adjust to produce comfortable stool). Faecal impaction: 8 sachets dissolved in 1 litre water, taken over 6 hours daily for up to 3 days.
Route: Oral
Frequency: Daily (constipation) or up to 8 sachets/day in 3 days (impaction)
Max: 8 sachets/day (impaction, max 3 days); 3 sachets/day (chronic constipation)
Each Movicol/Laxido sachet contains macrogol 3350 (13.125g) + electrolytes. Dissolve in water — do not take dry. Onset 24–48 hours. Preferred laxative in faecal impaction (NICE NG128). Faecal impaction regimen: 8 sachets/day for 3 days — ensure patient can tolerate fluid load (heart failure risk).

Paediatric dose

Route: Oral
Frequency: Daily
Max: 4 sachets/day (children 2–11 years)
BNF for Children: Movicol Paediatric Plain sachets (6.9g macrogol per sachet). Constipation: 2–5 years: 1 sachet/day; 6–11 years: 2 sachets/day (increase to max 4 sachets/day if needed). Faecal impaction 5–11 years: 4 sachets day 1, increasing by 2 per day to max 12/day if needed. 12–17 years: adult dose. Source: BNF for Children 2024; NICE NG128.

Dose adjustments

Renal

Caution in severe renal impairment — electrolyte content of each sachet may accumulate.

Hepatic

No dose adjustment required.

Clinical pearls

  • NICE NG128 (Faecal impaction): macrogol (Movicol) is first-line — superior to stimulant laxatives for impaction treatment.
  • Faecal impaction 8-sachet regimen: over 6 hours daily for 3 days. Warn patient of loose stool. Review after 3 days — if no response, consider manual evacuation under anaesthesia.
  • Long-term use for chronic constipation: well tolerated and effective. No evidence of tolerance or dependence.
  • Caution with faecal impaction regimen in heart failure — 1 litre/day extra fluid may precipitate decompensation.

Contraindications

  • Intestinal obstruction or perforation
  • Ileus
  • Toxic megacolon
  • Severe inflammatory bowel disease

Side effects

  • Abdominal distension and bloating (common, especially impaction dose)
  • Nausea
  • Diarrhoea (if overused)
  • Electrolyte disturbance (with high doses — rare)
  • Fluid overload (high dose in cardiac failure)

Interactions

  • No significant drug interactions (not absorbed)

Monitoring

  • Stool frequency and consistency
  • Hydration
  • Electrolytes (high dose/impaction regimen)
  • Fluid balance (cardiac risk patients)

Reference: BNFc; BNF 90; NICE NG128 Constipation; NICE CG99 Constipation in Children; SPC Movicol. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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