Osmotic Laxative Pregnancy: Can be used during pregnancy - no effects are anticipated since systemic exposure is negligible (limited data, fewer than 300 pregnancy outcomes; animal studies show no reproductive toxicity). Can be used during breast-feeding - no effects on the breast-fed infant are anticipated as systemic exposure is negligible.

Macrogol (Polyethylene Glycol)

Brand names: Movicol, Laxido, CosmoCol

Macrogol (polyethylene glycol) is an osmotic laxative, taken as oral powder dissolved in water, used to treat chronic constipation and faecal impaction.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 1 to 2 sachets per day (each sachet contains 10 g macrogol), preferably taken as a single dose in the morning.

Route: Oral - each sachet should be dissolved in a glass of water (approximately 125 ml) just before use; the resultant solution is clear and transparent like water

Frequency: Once daily (single morning dose); the daily dose should be adapted according to clinical effect and may range from one sachet every other day up to 2 sachets a day

Max: 2 sachets a day (the SPC states the daily dose may range from one sachet every other day up to 2 sachets a day)

It is recommended to drink 125 ml of liquid (e.g. water) after each dose. The effect becomes apparent within 24 to 48 hours after administration. Treatment should be stopped gradually and resumed if constipation recurs. Treatment of constipation with any medicinal product is only an adjuvant to a healthy lifestyle and diet. PAEDIATRIC (not a per-kg dose): the SPC gives the same regimen - 1 to 2 sachets per day, preferably as a single morning dose - and states that in children treatment should not exceed 3 months due to a lack of clinical data beyond 3 months; one sachet every other day is noted as especially applicable in children. Verify paediatric use against a children's formulary. CAUTION: in case of diarrhoea, caution in patients prone to disturbance of water and/or electrolyte balance (e.g. the elderly, patients with impaired hepatic or renal function, patients taking diuretics) and electrolyte control should be considered. SOURCE SCOPE: UK SPC for 'PegLax 10 g powder for oral solution in sachet' (macrogol 4000), a maintenance constipation product. High-dose faecal-impaction and bowel-preparation macrogol regimens are NOT covered by this label and must be sourced separately.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Severe inflammatory bowel disease (such as ulcerative colitis or Crohn's disease) or toxic megacolon, associated with symptomatic stenosis
Digestive perforation or risk of digestive perforation
Ileus or suspicion of intestinal obstruction
Painful abdominal syndromes of indeterminate cause

Side effects

Common: abdominal pain and/or distension, diarrhoea, nausea
Uncommon: vomiting, urgency to defecate, faecal incontinence
Very rare: hypersensitivity reactions (pruritus, rash, face oedema, Quincke oedema, urticaria, anaphylactic shock)
Not known: electrolyte disorders (hyponatraemia, hypokalaemia) and/or dehydration, especially in elderly patients
Rarely, severe hypersensitivity reactions and bronchospasm due to the presence of sulphur dioxide in this product

Interactions

Absorption of other medicinal products could be transiently reduced during use; the therapeutic effect of medicinal products with a narrow therapeutic index may be particularly affected (e.g. antiepileptics, digoxin and immunosuppressive agents)

Clinical monograph

How it works

Macrogol is an inert polymer that binds water osmotically and is not absorbed or metabolised, so it retains fluid within the bowel to increase stool volume and soften it, stimulating peristalsis and bowel evacuation.

Prescribing in practice

It is contraindicated in intestinal obstruction or perforation, ileus and severe inflammatory bowel conditions such as toxic megacolon, where stimulating bowel transit is dangerous.
Higher-volume regimens used for faecal impaction can cause fluid and electrolyte shifts, so caution is needed in frail, elderly or cardiovascularly impaired patients and adequate hydration is important.
Each sachet must be dissolved in the recommended volume of water before drinking to ensure the osmotic balance is correct.

Monitoring

Routine monitoring is not usually required, but consider fluid and electrolyte status when high doses are used for impaction or in vulnerable patients.

Counselling the patient

Dissolve each sachet fully in water before drinking and keep up your overall fluid intake.
When used to clear a blockage of hardened stool you may need to drink several sachets over the day as directed.

Evidence & guidelines

NICE recommends macrogols as a first-line osmotic laxative for chronic constipation and for the treatment of faecal impaction.

Reference: NICE NG128 Constipation; NICE CG99 Constipation in Children; SPC Movicol; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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