This page shows what was measured, who it was measured in, and what that does not settle.
What Polyethylene Glycol 3350 does in the body
Constipation — softening stool by keeping water in the bowel
Polyethylene glycol is a long chain of repeating units, each of which grabs onto water molecules and will not let go. Swallowed as a powder dissolved in a drink, it is far too large for the gut wall to absorb, so essentially the whole dose travels the length of the bowel carrying its water with it. That water cannot be reabsorbed while it is bound to the polymer, so the stool arriving at the rectum is softer and bulkier than it would otherwise be, and it moves more easily. Nothing is stimulated, nothing is blocked, and no nerve or receptor is involved — it is a physical effect, which is why it works the same way in a two-year-old and an eighty-year-old.
What happened in people
0.70 more stools per week than lactulose across six trials in 465 participants, with superiority also on stool form, abdominal pain and need for additional products
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 159 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Comparator
A comparator is whatever the treatment was measured against.
A picture of it, and where the picture fails
It is like the other runner in a race.
Where that stops being true. A race has one winner. A study can show both arms improved.
What people get wrong. Results are read without asking what the other group got. Beating nothing is not beating a treatment.
The control condition against which the experimental intervention is assessed.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Absolute difference
An absolute difference is how many more people in a hundred were affected.
A picture of it, and where the picture fails
It is like counting heads in two rooms of a hundred.
Where that stops being true. Heads are easy to count. Study results carry a margin of error too.
What people get wrong. It is confused with a percentage change, which can look far larger.
The arithmetic difference in event rates between arms.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
Frequency of defecation, measured as stools per week
✓ The study showed what it set out to show
Who was studied
Cochrane CD009118: osmotic and stimulant laxatives for childhood constipation
How many people
2310
Study design
Systematic review and meta-analysis of 25 randomised trials
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Polyethylene glycol against placebo, mean difference 2.61 stools per week (95% CI 1.15 to 4.08), 2 studies, 101 patients; against lactulose 0.70 (95% CI 0.10 to 1.31), 6 studies, 465 participants; high dose against low dose 1.30 (95% CI 0.76 to 1.84), 1 study, 90 participants
Repeated elsewhere
Partially Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. GRADE certainty for the primary outcome was low or very low. Fourteen of the 25 included studies were at high risk of bias. The placebo comparison rests on 101 patients across two trials.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Powder for oral solution, dissolved in water or another beverage; the bowel-preparation products are the same polymer in a large fluid volume with added electrolytes
Interval reported. 95% CI 1
Written into the record, not signed off as a reviewed claim.
Stools per week, polyethylene glycol against lactulose
✓ The study showed what it set out to show
Who was studied
Polyethylene glycol against lactulose, pooled paediatric comparison (Cochrane CD009118)
How many people
465
Study design
Meta-analysis of 6 randomised trials within a Cochrane systematic review
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Mean difference 0.70 stools per week (95% CI 0.10 to 1.31)
Repeated elsewhere
Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. Follow-up across the contributing studies was short. The separate Cochrane review of lactulose against polyethylene glycol in adults and children found the same direction on stool frequency, stool form, abdominal pain and need for additional products.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Powder for oral solution, dissolved in water or another beverage; the bowel-preparation products are the same polymer in a large fluid volume with added electrolytes
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
Change in constipation total sum score at week 52 against baseline, and dose range determination
✗ The study did not show it
Who was studied
PEG3350 with electrolytes against PEG4000, 52 weeks in children
How many people
97
Study design
Randomised, double-blind, non-inferiority trial
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Mean reduction -3.81 (95% CI -4.96 to -2.65) against -3.74 (95% CI -5.08 to -2.40); non-inferiority margin of 1.5 not met, observed maximum difference -1.81 to 1.68. Treatment success 50% against 45% at 52 weeks, P=0.69.
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. Ninety-seven children randomised, 82 completing, is a small sample for a year-long safety question. No drug-related serious adverse events occurred, which at this sample size cannot exclude an uncommon harm.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Powder for oral solution, dissolved in water or another beverage; the bowel-preparation products are the same polymer in a large fluid volume with added electrolytes
Interval reported. 95% CI -4
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 3 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Start
Polyethylene Glycol 3350
What a person takes: Powder for oral solution, dissolved in water or another beverage; the bowel-preparation products are the same polymer in a large fluid volume with added electrolytes.
The measurement behind this step
The formulation problem is the opposite of every other drug in this file. Nothing has to be protected, absorbed, targeted or delivered anywhere — the substance simply has to reach the colon dissolved in water, which it does by not being absorbable. The electrolyte-containing preparations exist because the fluid volumes used for colonoscopy preparation would otherwise shift sodium and potassium.
Getting in
Dissolved in a drink and swallowed
It is a powder that has to go into liquid. The liquid it goes into is part of how it works, not just how it is taken.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Polyethylene glycol 3350 is supplied as a powder for oral solution. The dissolved polymer enters the stomach already hydrated, and the water it arrives with is the water it carries onward. The higher-volume bowel-preparation products are the same polymer with added electrolytes, formulated so that the large fluid volume does not shift sodium and potassium.
A chain of about seventy-five linked units is much too large to slip between or through the cells lining the intestine. Essentially the entire dose stays inside the bowel.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Absorption is negligible. There is no transporter for it, and passive paracellular transport is excluded by size at a nominal average molecular weight of 3,350. Nothing is metabolised, nothing enters the systemic circulation in meaningful quantity, and the whole administered mass is recovered in stool.
The oxygen atoms spaced along the polymer each grab water molecules by hydrogen bonding. The water is held to the chain and cannot be reabsorbed while it is.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Each ether oxygen coordinates water through hydrogen bonding, giving the polymer a high water-binding capacity per gram. The bound water is osmotically unavailable to the colonic epithelium, so it remains in the lumen rather than being reabsorbed. No ion gradient is created and no secretion is stimulated — the effect is purely one of water retention.
Unlike lactulose and unlike the sugars in prunes, colonic bacteria cannot ferment this polymer. That is why it does not cause the bloating and wind that the older osmotic laxatives do.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
The polyether backbone is not a substrate for colonic bacterial glycoside hydrolases, so it passes through the fermentative compartment intact and produces no short-chain fatty acids and no gas. Lactulose is fermented completely, which is the mechanistic reason for the tolerability difference that the pooled trials measure.
What arrives at the rectum has more water in it and is easier to pass. Nothing has been stimulated and nothing has been forced — the physical properties of the stool have changed.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Retained luminal water increases stool volume and reduces consistency, which secondarily increases propulsive activity through normal stretch-mediated reflexes. The measured effect in randomised trials is 2.61 more stools per week than placebo in children, and 0.70 more per week than lactulose.
A substance that is not absorbed and not metabolised sounds like one that cannot cause harm over years. That reasoning is why the long-term trials were never thought necessary — and why the allergy reports came as a surprise.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
The absence of absorption and metabolism is the entire safety argument for daily use over years, and it is an argument from chemistry rather than from trial data: the Cochrane review calls for long-term research that has not been done, and the largest randomised long-term study includes 97 children over 52 weeks. Separately, the assumption of biological inertness has already failed once — immediate-type hypersensitivity to polyethylene glycols is reported with increasing frequency, including life-threatening reactions.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 6 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
Adults with occasional constipation, and a very large number of children with functional constipation, in whom it is the first-line agent in most guidelines worldwide. Also every adult preparing for a colonoscopy, in a different and much larger formulation.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
Where the result stopped carrying
The GRADE assessment: low or very low certainty for the primary outcome, with 14 of 25 trials at high risk of bias
The 52-week paediatric non-inferiority comparison, whose confidence interval was too wide to reach its own margin
The placebo evidence base, which for the most-used paediatric laxative in the world consists of two trials and 101 children
The assumption of inertness, contradicted by increasing reports of immediate-type hypersensitivity including life-threatening reactions
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to take◇Read from sources, not yet reviewed
Why it might seem to do nothing
A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.
It was studied in different people
The people in the studies were not much like the reader.
On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
The evidence may simply be wrong
Small early studies often do not hold up.
On this record: RNAWiki has not yet published a reviewed conclusion for this use.
Other reasons RNAWiki checked and found nothing for (11)
It was studied for a different goal
The studies measured something else entirely. Nothing in this record points to this reason.
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
There was nothing to correct
Where a level is already normal, topping it up may change nothing. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
The product may not be what it says
Contents of a sold product are not always what the label states. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.
None of these is a reason to take more. Taking more is not a step this page ever suggests.
What it would be like to take◇Read from sources, not yet reviewed
What taking it involves
The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.
How it is supplied
Prescription only
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Powder for oral solution, dissolved in water or another beverage; the bowel-preparation products are the same polymer in a large fluid volume with added electrolytes
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
RNAWiki has not recorded a supervision or regulatory status for this substance.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
No register row and no identity class settled the question.
No source is stored against this line.
What is in the pack
The formulation problem is the opposite of every other drug in this file. Nothing has to be protected, absorbed, targeted or delivered anywhere — the substance simply has to reach the colon dissolved in water, which it does by not being absorbable. The electrolyte-containing preparations exist because the fluid volumes used for colonoscopy preparation would otherwise shift sodium and potassium.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold and what that means for what is in the pack.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
The over-the-counter label directs use for up to seven days and advises stopping and consulting a doctor if there is rectal bleeding or failure to have a bowel movement. Commonly reported adverse effects in the randomised trials are flatulence, abdominal pain, nausea, diarrhoea and headache, at rates broadly similar to comparators. The substance is not absorbed and not metabolised in meaningful quantity. Immediate-type hypersensitivity to polyethylene glycols is reported with increasing frequency, including life-threatening reactions, and is under-recognised because polyethylene glycol is an excipient in a very wide range of unrelated products. Electrolyte disturbance is a concern with the high-volume bowel-preparation formulations rather than with the laxative doses.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.
Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What is missing or unclear◇Read from sources, not yet reviewed
Does the exact form matter?
Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.
The form that was studied
Powder for oral solution, dissolved in water or another beverage; the bowel-preparation products are the same polymer in a large fluid volume with added electrolytes
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
Nothing has to be protected, absorbed, targeted or delivered anywhere — the substance simply has to reach the colon dissolved in water, which it does by not being absorbable. The electrolyte-containing preparations exist because the fluid volumes used for colonoscopy preparation would otherwise shift sodium and potassium.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on which forms are sold and how they compare.
No source is stored against this line.
What is recorded as being sold
142 products list this as an active ingredient in the United States drug directory. 123 of them contain it and nothing else.
FDA National Drug Code directory · 76420-489 · read 2026-08-29
They are sold as granule, powder, powder, for solution and powder, for suspension, taken oral and topical.
FDA National Drug Code directory · 76420-489 · read 2026-08-29
The regulator's established pharmacologic class for it is osmotic activity [moa], osmotic laxative [epc] and stimulation large intestine fluid/electrolyte secretion [pe].
FDA National Drug Code directory · 76420-489 · read 2026-08-29
117 published labels name it as an active ingredient. 102 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 37c111ec-5b62-42b9-bbb2-3b0c530e34c9 · read 2026-08-29
Those labels are classed as human otc drug and human prescription drug.
US prescribing information · 37c111ec-5b62-42b9-bbb2-3b0c530e34c9 · read 2026-08-29
73 marketed supplement labels list this ingredient, classed as botanical, botanical with nutrients, mineral and other combinations.
Those labels carry all other, nutrient and structure/function claims. A claim of that kind is written by the manufacturer and is not assessed by any regulator, so its presence says nothing about whether it is true.
Polyethylene Glycol 3350 is oral at HOW SUPPLIED Polyethylene Glycol 3350 17g of white powder when filled to the indicated line (white section in cap)., recorded as fda label in effect 2025-09-30 in the United States.
US prescribing information · 5df518fb-ad58-4f17-af34-f66066f1313a · read 2026-08-30
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.
RNAWiki could not confidently classify this substance, so no self-experiment plan is offered.
Questions worth asking
Which of the trials of Polyethylene Glycol 3350 studied people like me?
What was measured, and for how long?
Was the result a laboratory value or a health outcome?
What would we watch for, and when would we stop?
Tracking can show whether something changed for you. It cannot show what caused it.
RNAWiki records evidence. It does not say whether this substance is right for you.
What is missing or unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That a substance safe for the seven days it is licensed for is safe for the years children actually take it, argued from non-absorption rather than measured
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That polyethylene glycol is biologically inert — an assumption a growing case literature of immediate-type hypersensitivity has already overturned
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That first-line guideline status reflects the strength of the underlying evidence, which Cochrane grades low to very low
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That more stools per week is the same as a child feeling better; the 52-week symptom-score trial is the only one that asked and it did not meet its margin
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read from sources, not yet reviewed
What nobody knows yet
Open questions, each with why it is open and what would close it.
Missing populations
Which groups were under-represented in the studies has not been recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing long-term data
No completed tested study window is recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
No reviewed conclusion
RNAWiki has not yet published a reviewed conclusion for this use.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing interaction studies
No interaction was found in the registers checked. Not finding one is not the same as showing there is none.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Formulation uncertainty
Several salts, forms or products of Polyethylene Glycol 3350 are recorded. Results from one form may not transfer to another.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Mechanism not reviewed
No reviewed mechanism story exists for this substance.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
What happened in people◇Read from sources, not yet reviewed
Check any of this yourself
Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.
Every line above can be traced to the study named beside it. Follow the link and read it.
It beats placebo by 2.61 stools per week — on two studies and 101 patients
In plain words
Children given polyethylene glycol had about two and a half more bowel movements a week than children given a dummy. That is a real difference and the number of children it rests on is very small: two trials and a hundred and one patients, out of a review of twenty-five trials.
What was measured
Stools per week against placebo, pooled across randomised trials in children
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Cochrane review of osmotic and stimulant laxatives in childhood constipation included 25 randomised trials in 2,310 participants. Meta-analysis of the two placebo-controlled studies, 101 patients in total, gave a mean difference of 2.61 stools per week in favour of polyethylene glycol (95% CI 1.15 to 4.08). A dose comparison in one study of 90 participants found high-dose (0.7 g/kg) gave 1.30 more stools per week than low-dose (0.3 g/kg) (95% CI 0.76 to 1.84). Common adverse events in the placebo-controlled studies were flatulence, abdominal pain, nausea, diarrhoea and headache. The GRADE assessment for the primary outcome was low or very low certainty, on grounds of sparse data, inconsistency and high risk of bias, and 14 of the 25 included studies were judged at high risk of bias from lack of blinding, incomplete outcome data and selective reporting.
Written into the record, not signed off as a reviewed claim
It beats lactulose across ten trials, on every measure that was pooled
In plain words
Against the older osmotic laxative it is usually compared with, polyethylene glycol produced more bowel movements, better stool consistency, more relief of abdominal pain and less need for additional products — in adults and children alike.
What was measured
Stool frequency, stool form, abdominal pain relief and need for additional products, polyethylene glycol against lactulose
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Cochrane review of lactulose against polyethylene glycol for chronic constipation considered all ten randomised trials then published and found polyethylene glycol superior on stool frequency per week, stool form, relief of abdominal pain and need for additional products. Subgroup analysis showed the advantage in both adults and children, except for abdominal pain relief. The paediatric review found the same direction with a quantified effect: 0.70 more stools per week (95% CI 0.10 to 1.31) across six studies in 465 participants, with 18% (27 of 154) of polyethylene glycol patients requiring additional laxative therapy against a higher proportion on lactulose. The mechanistic explanation is straightforward: lactulose is fermented by colonic bacteria and produces gas, and polyethylene glycol is not fermented at all.
Written into the record, not signed off as a reviewed claim
The evidence supporting the most-used laxative in childhood is graded low to very low certainty
In plain words
Twenty-five randomised trials exist. Fourteen of them were judged at high risk of bias. The reviewers who pooled them said the results should be interpreted with caution because of quality problems, inconsistency between studies and very short follow-up — for a drug children take for years.
What was measured
GRADE certainty rating for the primary outcome and risk-of-bias judgement across 25 included randomised trials
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The Cochrane review’s own summary is unusually blunt: the pooled analyses suggest polyethylene glycol may be superior to placebo, lactulose and milk of magnesia, but GRADE assessment indicated that overall quality of the evidence for the primary outcome, number of stools per week, was low or very low, owing to sparse data, inconsistency and high risk of bias in the pooled studies. Fourteen of 25 studies were at high risk of bias from lack of blinding, incomplete outcome data and selective reporting. The authors state that results should be interpreted with caution because of quality and methodological concerns, clinical heterogeneity and short follow-up, and that further research is needed into long-term use of polyethylene glycol for childhood constipation and into the optimal dose. That research has not arrived in the decade since. It is a striking position for a first-line, worldwide-guideline-recommended treatment in children.
Written into the record, not signed off as a reviewed claim
The only 52-week paediatric head-to-head did not meet its non-inferiority margin
In plain words
A trial followed children for a full year on one of two polyethylene glycol formulations. Half the children on each ended up with a satisfactory result. Formally, the trial failed to prove one was not worse than the other — the confidence interval was too wide to tell.
What was measured
Change in constipation total sum score at 52 weeks, and treatment success rate, between two polyethylene glycol formulations
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
A double-blind randomised trial in children aged 0.5 to 16 years with constipation, defined as fewer than three bowel movements a week, compared polyethylene glycol 3350 with electrolytes against polyethylene glycol 4000 without electrolytes over 52 weeks. Ninety-seven were included and 82 completed. Mean reduction in total sum score, the sum of five constipation symptoms each rated 0 to 3, was -3.81 (95% CI -4.96 to -2.65) and -3.74 (95% CI -5.08 to -2.40) respectively. The prespecified non-inferiority margin was a difference of 1.5 or less; the observed maximum difference between groups spanned -1.81 to 1.68 and the criteria were not met. Treatment success — three or more bowel movements a week with fewer than one episode of faecal incontinence — was 50% and 45% at 52 weeks (P=0.69). Adverse event rates were similar and no drug-related serious adverse events occurred. The authors state that non-inferiority was not demonstrated while secondary outcomes suggest similar efficacy and safety, which is the honest reading and a weaker claim than the one usually made from this trial.
Written into the record, not signed off as a reviewed claim
Licensed for seven days, taken for years — and the long-term safety question is open by admission
In plain words
The label on the box says use for up to seven days. Children with functional constipation take it daily for months or years, in every major guideline. Almost none of the randomised evidence covers that, and the reviewers who assembled it said so explicitly.
What was measured
That a substance safe for seven days of licensed use is safe for years of unlicensed daily use in children, on the grounds that it is not absorbed — the reasoning is sound and the trial evidence for it does not exist
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The over-the-counter labelling for polyethylene glycol 3350 specifies use for up to seven days. Guideline-recommended paediatric practice is maintenance therapy for months, often for more than a year, because functional constipation in children relapses when treatment stops early. The randomised literature does not follow that: the Cochrane review notes short follow-up as one of the reasons for caution and calls for research into long-term use. The single 52-week randomised trial included 97 children and found no drug-related serious adverse events, which is reassuring at that sample size and cannot exclude an uncommon harm. The proposed mechanism of safety — that the polymer is too large to be absorbed and is not metabolised — is chemically sound and is the basis of the extrapolation, but it is a mechanistic argument standing where trial data should be. This record states that as an inference rather than as a finding.
Written into the record, not signed off as a reviewed claim
The inert excipient turned out to be an allergen
In plain words
Polyethylene glycol is in an enormous number of medicines, cosmetics and household products, and was treated for decades as biologically inert. Immediate allergic reactions to it, some life-threatening, are being reported with increasing frequency, and most clinicians do not know to look for it.
What was measured
That polyethylene glycol is biologically inert and cannot be an allergen — a long-held assumption that a growing case literature has overturned, without yet establishing how common the reaction is
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The 2016 review that established the pattern is explicit about the shape of the problem: polyethylene glycols are widely used and generally considered biologically inert, cases of mild to life-threatening immediate-type hypersensitivity are reported with increasing frequency, and awareness of allergenic potential remains low because of a general lack of suspicion toward excipients and insufficient product labelling. The information available is limited to anecdotal reports, and the potential for sensitisation and cross-sensitisation to PEGylated drugs and structurally related derivatives is likely underestimated. The characteristic presentation is a patient with a history of repeated severe reactions to a range of apparently unrelated products in hospital and at home — because the common factor is an excipient nobody is reading the label for. This is a change in how the field regards the substance rather than a change in the substance, and it is directly relevant to the polyethylene glycol content of lipid nanoparticle formulations.
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What is not here
7 questions this page could not answer
These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.
What was measured, goal by goal — found nothing in the sources checked.
How close this is to real life — found nothing in the sources checked.
Felt, measured, or meaningful — found nothing in the sources checked.
How long anything takes — found nothing in the sources checked.
What it may clash with — found nothing in the sources checked.
Other ways to the same goal — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
The full record, for auditing
Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.
The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
A chain of ethylene oxide units, far too large to be absorbed and with no receptor anywhere in the body, that works purely by holding water in the bowel through hydrogen bonding: it adds a measured 2.61 stools per week over placebo in children, beats lactulose by 0.70 stools per week across six trials, and Cochrane grades the certainty of that primary evidence as low to very low, on 25 trials of which 14 were at high risk of bias — for a product licensed for seven days of use and given to children daily for years.
Recorded evidence blocks (7)
Q1
On the Polyethylene Glycol 3350 label: indicated for what?
126 registered trials of Polyethylene Glycol 3350 — at which phases?
Registered studies posting no result
100 of 126
126 registered studies of Polyethylene Glycol 3350: 49 phase4, 39 na, 18 phase3, 14 phase2, 8 phase1, 2 early phase1, 2 na or unstated. CLINICALTRIALS_SNAPSHOT · 2026-09-01
45 with a PubMed record
Show the evidence
phase4
49
na
39
phase3
18
phase2
14
phase1
8
early phase1
2
9 more recorded rows
na or unstated
2
completed
76
unknown
22
terminated
9
recruiting
8
withdrawn
7
enrolling by invitation
2
active not recruiting
1
not yet recruiting
1
recorded 2026-09-01 · last checked 2026-09-04
Q3
13 of Polyethylene Glycol 3350's trials stopped: accrual/recruitment, funding/business, other?
accrual/recruitment (5), funding/business (1) and other (7): Polyethylene Glycol 3350's stop wording, clustered. CLINICALTRIALS_SNAPSHOT · 2026-09-01
"concern patients in oral cleaout arm had worse outcome"; 13 of 126 registered studies
Show the evidence
Trial
NCT00467350
terminated; "concern patients in oral cleaout arm had worse outcome"
NCT00558376
terminated; "Study terminated due to FDA alert regarding Fleet phosphosoda"
NCT01717456
terminated; "Low enrollment led sponsor to terminate study early."
NCT01923376
withdrawn; "Not enough staff to collect data"
NCT02070341
terminated; "Significant changes to protocol and study design, study stopped to further enrollment and new study designed."
NCT02336906
withdrawn; "Changes in departmental staff have led to a cut in research alotments."
7 further recorded trials
NCT02337413
withdrawn; "Changes in departmental staff have led to a cut in research alotments."
NCT02609607
terminated; "Poor enrollment; funding ending Dec 31, 2018."
NCT02705378
withdrawn; "PI left institution. Protocol never submitted to the IRB, no contract executed only Confidentiality Agreement, and study not done."
NCT02893748
withdrawn; "unable to agree on budget terms"
NCT02977286
terminated; "Poor enrollment"
NCT04270019
withdrawn; "lack of staff, REB closed the file due to expired renewal"
NCT04585542
terminated; "Low enrollment rate"
recorded 2026-09-01 · last checked 2026-09-04
Q4
Human studies of Polyethylene Glycol 3350 used Polyethylene Glycol 400 0.4% — over how long?
Human studies of Polyethylene Glycol 3350 used "Polyethylene Glycol 400 0.4%". ClinicalTrials.gov · 2026-09-01
Show the evidence
humanNCT06750445
Polyethylene Glycol 400 0.4%
recorded 2026-09-01 · last checked 2026-09-04
Q5
Which 48 trials of Polyethylene Glycol 3350 posted no result?
Posted no result
48 of 48 completed trials
Registrations
NCT00750763, NCT01879605, NCT00745147, NCT01610856, NCT01229800 and NCT01533090, and 42 more
Completion dates
oldest 2008-12; newest 2023-12-13
Show the evidence
Trial
NCT00750763
2008-12
NCT01879605
2009-12
NCT00745147
2010-04
NCT01610856
2010-06
NCT01229800
2010-10
NCT01533090
2010-11
14 further recorded trials
NCT01518790
2011-08
NCT01531140
2011-11
NCT01592734
2011-11
NCT01834742
2011-12
NCT01675739
2012-04
NCT01011426
2012-06
NCT01299779
2012-09
NCT01778192
2012-12
NCT01243736
2013-11
NCT01714466
2014-01
NCT01840553
2014-03
NCT01887158
2014-06
NCT02009202
2014-06
NCT00765557
2014-07-22
Q6
At the median, Polyethylene Glycol 3350's trials enrolled 129.5 people — anything larger?
Median enrolment
129.5
Largest enrolment
13393
Registered trials counted
126
Q7
What do 1011 spontaneous reports say about Polyethylene Glycol 3350 — and not say?
These are reports people sent to a regulator. They do not show the medicine caused the reaction. Nobody counted how many people took the medicine and reported nothing. The same event can be reported more than once, and many reports are incomplete. News coverage, lawsuits and new warnings change how often people report. A count is not a rate and not a risk.
Polyethylene Glycol 3350 appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 1011 reaction mentions were counted: diarrhoea 189; vomiting 161; constipation 115; hyponatraemia 114. FAERS via Open Targets · CHEMBL1201479 · 2026-06-24
Show the evidence
diarrhoea
189
vomiting
161
constipation
115
hyponatraemia
114
abdominal pain
100
dehydration
86
4 more recorded rows
acute kidney injury
67
hyperkalaemia
60
oedema peripheral
60
pharmaceutical product complaint
59
recorded 2026-06-24 · last checked 2026-09-04
Where it is registeredIdentifiers, relations and other names
ChEMBL 37 — CC BY-SA 3.0 Unported · ClinicalTrials.gov — US Government work · Open Targets 26.06 — CC0 · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
✗ required summary fields resolved: 4 required field(s) not terminal: Why people use it, Best-supported result, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 6 source rows
✓ no critical contamination: no quarantine open
✓ canonical metadata passed: slug and display name present
✓ no raw internal fields: enforced by the copy-contract test over the rendered page
This is a record of evidence. It is not medical advice, and it does not say this substance suits you. Nothing here says any substance on RNAWiki is appropriate for a child.