MiraLAX

Pronunciation: MEER-uh-lax.

Generic name
polyethylene glycol 3350 (PEG 3350)
Drug class
Osmotic laxative
Form
Powder for oral solution
Route
Oral
Legal status
Over-the-counter (OTC) in the United States and Canada (as a monograph/non-prescription product); the electrolyte-containing PEG 3350 products available in the UK, EU, Australia, and New Zealand are also generally available without a prescription, subject to local pharmacy classification

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Movicol (macrogol 3350 plus electrolytes) (5) · Full directory

What polyethylene glycol 3350 (PEG 3350) is and how it works

MiraLAX is an over-the-counter osmotic laxative used for occasional constipation. Its only active ingredient is polyethylene glycol 3350 (PEG 3350), a substance that holds water in the intestine to soften stool and stimulate a bowel movement, generally within 1 to 3 days. (1)

MiraLAX does not carry a boxed warning -- it is regulated in the US as an over-the-counter monograph product, not a prescription medicine. It does carry standard, real over-the-counter safety guidance: it is meant for short-term, occasional use (the US label specifies not longer than 7 days without talking to a doctor), and certain symptoms (rectal bleeding, worsening abdominal pain, new diarrhoea) mean you should seek medical evaluation promptly. A real, important point for anyone comparing brands internationally: the common PEG 3350 laxative powders sold in the UK, Europe, Australia, and New Zealand (such as Movicol, Laxido, or Molaxole) are not the same formulation as MiraLAX -- they contain added electrolytes (salts), which MiraLAX does not, and which carry their own separate warning about fluid and electrolyte balance.

Mechanism of action: how polyethylene glycol 3350 (PEG 3350) works

Polyethylene glycol 3350 is a poorly absorbed, metabolically inert osmotic agent that retains water within the intestinal lumen, increasing stool water content and volume, which stimulates colonic motility and eases defecation. When combined with added electrolytes (sodium, potassium, bicarbonate/chloride), the electrolytes are designed to be exchanged across the intestinal mucosa with minimal net gain or loss of body sodium, potassium, or water, though real fluid/electrolyte-shift adverse effects are still documented with that formulation. (1) (2)

What polyethylene glycol 3350 (PEG 3350) is used for

Occasional constipation

Used for the relief of occasional constipation in adults. It generally produces a bowel movement within 1 to 3 days of use. (1)

Chronic constipation and faecal impaction (electrolyte-containing PEG 3350 products)

The electrolyte-containing macrogol 3350 products available in the UK, EU, Australia, and New Zealand (Movicol, Laxido, Molaxole, and similar) are additionally used, under medical guidance, for chronic constipation and to resolve faecal impaction -- a different labelled scope from MiraLAX's own occasional-use indication in the US. (2)

Before taking polyethylene glycol 3350 (PEG 3350)

Do not take / not appropriate for

  • Do not use if you are allergic to polyethylene glycol. (all countries) (1)
  • Do not use if you have kidney disease, unless a doctor has advised and is supervising your use. (United States) (1)
  • For the electrolyte-containing PEG 3350 products: do not use if you have a bowel obstruction or perforation, ileus, severe inflammatory bowel disease (such as Crohn's disease or ulcerative colitis), or toxic megacolon. (United Kingdom, European Union, Australia, New Zealand) (2)

Tell your clinician about

  • Whether you have kidney disease.
  • Whether you have nausea, vomiting, or abdominal pain, or a sudden change in bowel habits lasting more than 2 weeks.
  • Whether you have irritable bowel syndrome.
  • Any prescription medicines you take, especially if you plan to use this for more than a few days.
  • Whether you are pregnant or breastfeeding.
(1)

How to take polyethylene glycol 3350 (PEG 3350)

  • Fully dissolve the labelled dose of powder in 4-8 ounces (about 120-240 mL) of any beverage -- cold, hot, or at room temperature -- and drink once daily.
  • Do not use for more than 7 days in a row without talking to a doctor, for the plain MiraLAX/RestoraLAX formulation.
  • For the electrolyte-containing products (Movicol, Laxido, Molaxole, and similar), follow your product's own label or your prescriber's specific instructions, since these products are also used for longer-term, medically supervised constipation management at different doses.
(1) (2)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)

Missed dose

MiraLAX is generally used as needed for occasional constipation rather than on a strict daily schedule; if you are using an electrolyte-containing product on a prescribed regular schedule and miss a dose, contact your doctor or pharmacist for guidance rather than doubling a later dose.

Overdose

Using much more than the labelled dose can cause severe diarrhoea and dehydration, or (for electrolyte-containing products) a risk of electrolyte imbalance. Contact a doctor, pharmacist, or poison control, or seek emergency care, if a large overdose is taken or if severe symptoms develop. (1) (2)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Loose, watery, or more frequent stools.

What to notice: Loose, watery, or more frequent stools.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Bloating or gas.

What to notice: Bloating or gas.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Abdominal cramping.

What to notice: Abdominal cramping.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Nausea.

What to notice: Nausea.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Serious warnings

Rectal bleeding or worsening abdominal symptoms — serious

Symptoms: Rectal bleeding, or nausea, bloating, cramping, or abdominal pain that gets worse rather than better.

Action: Seek medical evaluation promptly -- these can be signs of a more serious underlying condition that needs medical evaluation, not simple constipation. (1)

Diarrhoea or need for use beyond 7 days — serious

Symptoms: New diarrhoea while using this product, or a felt need to keep using it for longer than 7 days.

Action: Seek medical evaluation promptly -- occasional-use laxatives like MiraLAX are not intended for continuous long-term use without medical supervision. (1)

Signs of fluid or electrolyte imbalance (electrolyte-containing PEG 3350 products only) — serious

Symptoms: Swelling (oedema), shortness of breath, increasing tiredness, signs of dehydration, or worsening heart failure symptoms.

Action: Contact your prescriber about the electrolyte-containing product (such as Movicol, Laxido, or Molaxole) immediately and contact your doctor, who will check your blood electrolytes and correct any imbalance -- this warning applies specifically to the electrolyte-containing formulations, not to plain, electrolyte-free MiraLAX or RestoraLAX. (2)

Interactions

  • Ask a doctor or pharmacist before use if you are taking a prescription medicine, since taking any oral medicine close to a large laxative dose can affect how well it is absorbed. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

The US label reviewed advises asking a health professional before use if pregnant. The UK source reviewed for the electrolyte-containing formulation states no adverse effects are anticipated during pregnancy, since systemic absorption of macrogol 3350 is negligible. (1) (2) (3) (4) (5) (6)

Breastfeeding

The US label reviewed advises asking a health professional before use if breastfeeding. The UK source reviewed states similar reasoning applies to breastfeeding as to pregnancy, given negligible systemic absorption. (1) (2) (3) (4) (5) (6)

Children

The US label reviewed directs parents/caregivers to ask a doctor before use in children under 17. The electrolyte-containing products (Movicol, Molaxole) have separate paediatric-specific formulations and dosing under medical guidance, not covered by this page's adult-focused content. (1) (2) (3) (4) (5) (6)

Elderly

No specific dose adjustment based on age alone is described in the sources reviewed; the electrolyte-containing product's dosing guidance applies equally to adults, adolescents, and elderly patients per the UK source reviewed. (1) (2) (3) (4) (5) (6)

Hepatic_impairment

Not specifically addressed in the sources reviewed, consistent with this medicine's minimal systemic absorption. (1) (2) (3) (4) (5) (6)

Renal_impairment

The US label reviewed specifically advises against use in kidney disease except under a doctor's advice and supervision. (1) (2) (3) (4) (5) (6)

Monitoring

Before starting

  • Confirmation that symptoms are consistent with simple occasional constipation, not a condition needing medical evaluation

During treatment

  • Watch for rectal bleeding or worsening abdominal pain, which mean you should seek medical evaluation promptly.
  • Track how many days you have used the product -- seek medical evaluation promptly if you need it for more than 7 days (plain PEG 3350) or as otherwise directed by your prescriber for electrolyte-containing products used long-term.
  • For electrolyte-containing products, watch for and report any signs of fluid/electrolyte imbalance (swelling, breathlessness, fatigue) to your doctor promptly.
(1) (2)

Storage

Store at 20-25°C (68-77°F). Check that the tamper-evident seal under the cap is unbroken before first use.

Professional information

Clinician-facing context only, sourced from the current US FDA OTC Drug Facts label and the UK emc Movicol SmPC reviewed for this dossier; verify against the current full label before recommending.

United States / Canada (plain, electrolyte-free PEG 3350: MiraLAX/RestoraLAX)

Indication: Occasional constipation

Dose summary: 17 g dissolved in 4-8 oz liquid once daily; not for use beyond 7 days without medical advice.

Renal context: Avoid in kidney disease except under a doctor's specific advice and supervision. (1) (4)

United Kingdom / European Union / Australia / New Zealand (macrogol 3350 plus electrolytes: Movicol, Laxido, Molaxole)

Indication: Chronic constipation; faecal impaction

Dose summary: Chronic constipation: 1-3 sachets/day in divided doses. Faecal impaction: up to 8 sachets within 6 hours, under medical supervision.

Renal context: Not specifically detailed with a dose adjustment in the sources reviewed; the added-electrolyte formulation carries its own fluid/electrolyte-shift warning requiring monitoring. (2)

Mechanism of action

Hepatic guidance

Not applicable given minimal systemic absorption.

Overdose note

Excess use can cause significant diarrhoea and dehydration; for electrolyte-containing formulations, extensive fluid loss from diarrhoea or vomiting may require correction of electrolyte disturbances under medical supervision. (1) (2)

Frequently asked questions

Is MiraLAX the same product as Movicol, Laxido, or Molaxole in other countries?

Not exactly. MiraLAX (US) and RestoraLAX (Canada) are plain polyethylene glycol 3350 with no added electrolytes. Movicol, Laxido, and Molaxole (commonly available in the UK, EU, Australia, and New Zealand) contain the same core ingredient, macrogol 3350, but with added electrolytes (sodium chloride, sodium bicarbonate, potassium chloride) -- a genuinely different formulation, with its own separate warning about fluid and electrolyte balance that does not apply to the electrolyte-free products. (1) (2) (4)

Does MiraLAX have a boxed warning?

No. MiraLAX is regulated in the US as an over-the-counter monograph product (Drug Facts label), a category that does not carry boxed warnings. A direct review of its current label confirms none is present. It does carry standard OTC safety guidance, including a 7-day maximum use period and 'Seek medical evaluation promptly' instructions for certain symptoms. (1)

Why does the electrolyte-containing version (Movicol/Laxido/Molaxole) have a fluid/electrolyte warning that MiraLAX doesn't?

Because that formulation adds real electrolytes (sodium, potassium, bicarbonate/chloride salts) to the macrogol 3350, and in some patients this can cause genuine shifts in the body's fluid and electrolyte balance -- with symptoms like swelling, shortness of breath, or worsening heart failure -- that require stopping the product and checking blood electrolytes. Plain, electrolyte-free MiraLAX does not add these electrolytes, so this specific warning does not apply to it in the same way. (2)

What is the mechanism of action of polyethylene glycol 3350 (PEG 3350)?

Polyethylene glycol 3350 is a poorly absorbed, metabolically inert osmotic agent that retains water within the intestinal lumen, increasing stool water content and volume, which stimulates colonic motility and eases defecation. When combined with added electrolytes (sodium, potassium, bicarbonate/chloride), the electrolytes are designed to be exchanged across the intestinal mucosa with minimal net gain or loss of body sodium, potassium, or water, though real fluid/electrolyte-shift adverse effects are still documented with that formulation. (1) (2)

What is the generic name of MiraLAX?

The generic name is polyethylene glycol 3350 (PEG 3350). (1) (2) (4)

What class of drug is polyethylene glycol 3350 (PEG 3350)?

MiraLAX is classed as: Osmotic laxative. (1) (2) (4)

References

  1. MIRALAX (polyethylene glycol 3350) powder, for solution -- Drug Facts labelU.S. Food and Drug Administration / DailyMed (NIH), OTC Drug Facts label, Bayer · United States · dated 2025-01-01 · accessed 2026-07-30 · source 1
  2. MOVICOL Plain 13.7g, powder for oral solution -- Summary of Product Characteristics (SmPC)electronic medicines compendium (emc), United Kingdom -- Summary of Product Characteristics · United Kingdom · dated 2026-01-01 · accessed 2026-07-30 · source 2
  3. Macrogol 3350 -- list of nationally authorised medicinal products (PSUSA/0001924/201905)European Medicines Agency (EMA) -- list of nationally authorised medicinal products (periodic safety update single assessment, PSUSA/0001924/201905) · European Union · dated 2019-05-01 · accessed 2026-07-30 · source 3
  4. RestoraLAX (polyethylene glycol 3350) -- product label (DIN 02318164)Health Canada -- non-prescription drug product listing (Drug Product Database), RestoraLAX product label · Canada · dated 2020-04-13 · accessed 2026-07-30 · source 4
  5. MOVICOL Ready to Take (macrogol 3350 and electrolytes) -- Product InformationTherapeutic Goods Administration (TGA), Australia -- product information referencing ARTG registration · Australia · dated 2021-10-29 · accessed 2026-07-30 · source 5
  6. MOLAXOLE and MOVICOL (macrogol 3350 with electrolytes) -- New Zealand Data Sheets and CMIMedsafe (New Zealand Medicines and Medical Devices Safety Authority) -- New Zealand Data Sheets and Consumer Medicine Information · New Zealand · dated 2026-01-01 · accessed 2026-07-30 · source 6

Brand names by country

Single-ingredient polyethylene glycol 3350 (PEG 3350) names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • clearlax17 g7g · amazon.com services llc
  • GAVILAX17 g7g · lupin pharmaceuticals,inc.
  • MiraLAX17 g7g · bayer healthcare llc.
  • Good Sense Clear Lax17 g7g · l. perrigo company
  • clear lax17 g7g · hyvee inc
  • rugby PEG 335017 g7g · bryant ranch prepack
  • dg health clearlax17 g7g · dolgencorp inc
  • Topcare ClearLax17 g7g · topco associates llc
  • purelax17 g7g · cvs pharmacy
  • basic care clearlax17 g7g · amazon.com services llc

United Kingdom

  • Movicol / Movicol Plain / Laxido (macrogol 3350 plus electrolytes) (2)emc current smpc confirmed · 13.125 g macrogol 3350 plus electrolytes per sachet · Norgine (Movicol) and other manufacturers (Laxido, CosmoCol)

Canada

  • LAX-A-DAY
  • RESTORALAX
  • CLEARLAX
  • PEGALAX
  • RELAXA
  • PEG
  • EMOLAX
  • PURELAX
  • LAX-A-DAY PHARMA
  • LAX-A-DAY MEN

Australia

  • Movicol (macrogol 3350 plus electrolytes) (5)tga artg registered confirmed · 13.125 g macrogol 3350 plus electrolytes per sachet · Norgine

New Zealand

  • Molaxole; Movicol (macrogol 3350 plus electrolytes) (6)medsafe datasheet and cmi confirmed · 13.125 g macrogol 3350 plus electrolytes per sachet · Multiple manufacturers
View brands in additional countries.

European Union

Movicol (macrogol 3350 plus electrolytes); Forlax (macrogol 4000, a related but chemically distinct product) (3)

This page provides general reference information about MiraLAX (polyethylene glycol 3350) and is not a substitute for advice from a doctor or pharmacist. Follow the product label for your specific market, and ask a doctor or pharmacist before use if you have kidney disease, are pregnant or breastfeeding, or need to use a laxative for longer than the labelled duration.

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