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Polyethylene glycol 3350

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Findings for this medication

Research about this medication, graded for how strongly each finding can be attributed to it. Nothing here describes your own levels.

Polyethylene glycol 3350 has no classical depletion machinery. It is minimally absorbed (urinary recovery of 0.28% or less in the pharmacokinetic work summarized in source [5]), the labels opened for this review describe no metabolism or enzyme effects, and the one label that addresses it states no effect on active absorption or secretion of glucose or electrolytes [2]. Its intended pharmacology, osmotic water retention in stool, and the loose stools that follow are not graded as a nutrient problem (Hard Rule 2). No entry qualified for red or orange: no study located measured a vitamin, trace mineral or antioxidant marker in people taking PEG 3350 and found a change.

ATC A06AD15 (macrogol) · reviewed 2026-10-04. This describes research about the medication. It does not say anything about your own levels or health.

How to read the evidence grades

These colours describe how strongly a finding can be attributed to the medication in the research. They are not a severity score and they say nothing about your own health.

Grades describe how strongly a finding can be attributed to Polyethylene glycol 3350 in the research — not how common it is, how serious it would be, and not anything about you personally.

Red — Severe
Two or more independent Tier A sources, this drug in the cohort, the nutrient directly measured, consistent direction, clinically meaningful magnitude, a named mechanism, no substantial contradicting Tier A evidence.
Orange — Moderate
At least one Tier A source with this drug in the cohort showing a real but bounded deficit: an exposure window, a subgroup, low frequency, or a functional rather than circulating deficit.
Yellow — Low
Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction.
Not graded — disclosed evidence gap
Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result.Source definition: Not gradeable under the rules above because nothing has been measured. Published as a documented gap, never as reassurance that there is no effect.

What the research found

Sodium, dilutional hyponatremia: one case report with systemic absorption in ileus (excess and dilution direction)

Yellow — Low

See study details

A 69-year-old man with ileus and increased intestinal permeability developed iso-osmolar hyponatremia (sodium nadir 122 mmol/L) on PEG 3350 without electrolytes; the mechanism was absorbed PEG drawing water into the vascular space.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. Yellow

Limits on what this shows

  • Negative and null findings: Pashankar 2003 (n=83 children, mean 8.7 months, range 3 to 30, mean 0.75 g/kg/day): serum sodium, potassium, chloride, carbon dioxide, osmolality and creatinine were normal [6]. Worona-Dibner 2023 (n=83, 12 months, PEG 3350 without electrolytes versus magnesium hydroxide): no severe clinical or biochemical adverse events [7].
  • At-risk subgroups: Hypothesis from the single case: ileus or altered mucosal permeability, kidney disease, high or escalated dosing, older adults. Not shown in any cohort.

Regulatory status

OTC label warns against use in kidney disease without supervision and limits use to 7 days [1]. The NF label states no effect on active electrolyte absorption or secretion [2].

Population evidence

Tier B case report (Tucker 2021, Clinical Kidney Journal): 69-year-old man, advanced pulmonary sarcoidosis, hospitalized for pneumonia; PEG 3350 17 g twice daily, raised to 34 g twice daily; measured osmolality 277 versus calculated 258 mOsm/kg (gap 19); authors also describe solvent-drag potassium shift and mild osmotic nephropathy [9].

Mechanism

Named: systemic absorption of PEG during ileus with heightened permeability, producing an osmotic water shift (a dilution and retention disturbance, not intake-related loss) [9]. Also noted in a StatPearls summary: one case of hyponatremic seizures after bowel preparation, a different formulation [4].

Counter-evidence held on record

Counter-evidence on record Two Tier A pediatric cohorts show normal electrolytes at labeled-range doses [6], [7]. A 14-day adult trial at 17 g daily reported no serious adverse events [8], though it did not itemize electrolytes in the text opened. Framing caution This is a retention and dilution risk in an unusual setting, not a dietary sodium shortfall. Increasing salt or sodium intake is not the remedy; the hazard is the fluid shift. Loose stools from the drug's intended action are not graded here.

Phosphate, excess direction: early-test hyperphosphatemia in a PEG 4000 pediatric cohort (class extrapolation)

Yellow — Low

See study details

CLASS EXTRAPOLATION. In 100 children on long-term PEG 4000, hyperphosphatemia appeared in 10% on initial testing and mostly resolved while treatment continued; PEG 3350 was not in this cohort.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. Yellow

Limits on what this shows

  • Negative and null findings: In a PEG 3350 cohort, no hypophosphatemia was detected over 12 months [7]; hyperphosphatemia was not itemized in the summary opened.
  • At-risk subgroups: Not defined.

Cohort test

Bae 2010 studied PEG 4000, not PEG 3350 [13]. Both are macrogols with the same osmotic mechanism and negligible absorption, so a class-level reading is defensible but remains Tier C for this drug. Not carried above yellow.

Population evidence

Prospective observational, serial biochemistry, n=100 children, mean 16.93 months (range 7 to 46). Hyperphosphatemia in 10% at initial testing, mostly spontaneous resolution despite continued treatment, no significant relation to dose or duration; one case of hypernatremia and one of leucopenia [13]. No comparator group was described in the summary opened.

Mechanism

Absent. No mechanism linking a non-absorbed polymer to raised serum phosphate is named in any source opened. Confounding by indication (constipation, dehydration, age-related reference ranges) is not excluded.

Counter-evidence held on record

Counter-evidence on record The finding is transient and dose-independent, which weakens a causal reading; the same biochemistry in a PEG 3350 cohort showed no abnormal phosphate flag [7]. Framing caution This runs in the excess direction. Phosphate supplementation or restriction advice is not supported by it, and no dose is suggested. Class-level label: do not attribute to PEG 3350 specifically.

The five body-system areas

Each finding is counted once, in a single area. Where a study is mentioned in a second area it is context only.

Mitochondrial Burden

Each finding below is counted once, in this area only.

Mitochondrial burden

Not graded — disclosed evidence gap

See study details

No PEG 3350 study of mitochondrial structure, electron transport or biogenesis was located.

Full detail and limits

What the grade means here: Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result. Ungraded

Limits on what this shows

  • Why no grade: Dual condition met: no verified Tier B or C source, and no circulating claim about mitochondria found in the consumer pages opened [17], [18], [19], [20], [21]. The one oxidative-stress source opened [22] measured malondialdehyde and cytokines, not mitochondrial structure, electron transport or biogenesis, so it does not support a mitochondrial grade. Classification: partly tooling-limited, not a confirmed gap.

Channels tried

WebFetch PubMed listing "polyethylene glycol 3350 AND (oxidative stress OR mitochondrial)": 3 records, none an oral PEG laxative mitochondrial study (one oxidative-stress lead, see Oxidative stress). WebFetch PubMed listing "polyethylene glycol laxative mitochondria": HTTP 429, not retrieved (proxy asked not to refetch). WebSearch, one query combining oxidative stress, mitochondrial and ATP with intestinal epithelium: no oral PEG laxative mitochondrial paper by title (titles only, not opened). Revision pass: WebFetch PubMed listing "polyethylene glycol 3350 mitochondrial ATP": zero records. A second phrasing (macrogol OR PEG 3350 with ATP, energy metabolism, respiratory chain, mitochondrial membrane, format=pubmed) returned a generic trending-articles page rather than search results and is not counted as a valid search. WebFetch OpenAlex search "polyethylene glycol 3350 mitochondria": HTTP 429 via proxy, not retrievable, proxy asked not to refetch. Europe PMC and OpenAlex earlier via WebFetch: 429. curl channels: 403. WebSearch budget then exhausted.

Revisit

Retry PubMed with alternate phrasings (macrogol, colonocyte, ATP) when the listing host is not rate-limited.

Oxidative Stress

Each finding below is counted once, in this area only.

Oxidative stress, reverse direction: lower lipid-peroxidation markers in a rat methotrexate liver-injury model after intraperitoneal PEG 3350

Yellow — Low

See study details

In rats given methotrexate, intraperitoneal PEG 3350 was followed by lower plasma and liver malondialdehyde than saline; this is an antioxidant-direction animal signal by a non-oral route, not an oxidative-stress burden from the drug and not a nutrient deficiency.

Full detail, limits and 1 references

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. Yellow

Limits on what this shows

  • Negative and null findings: No human study of oxidative-stress or antioxidant-capacity markers in PEG 3350 users was located (PubMed listing "polyethylene glycol 3350 AND (oxidative stress OR mitochondrial)": 3 records, this rat paper the only PEG 3350 laxative-relevant lead). The two pediatric safety cohorts did not report redox markers [6], [7].
  • At-risk subgroups: None defined. No human population is implicated.

Regulatory status

Neither label opened carries an antioxidant or oxidative-stress statement [1], [2].

Population evidence

Tier B, drug-specific, animal. Acar 2022 (Acta Cirurgica Brasileira, PMID 35894304): 30 male rats, 10 given no drugs and 20 given single-dose methotrexate; the MTX rats then received PEG 3350 30 mg/kg/day (Merck) or 0.9% saline, both intraperitoneally, daily for two weeks. Transforming growth factor beta, plasma malondialdehyde (MDA), liver MDA, serum tumour necrosis factor alpha, alanine aminotransferase, plasma pentraxin-3, and histology (hepatocyte necrosis, fibrosis, cellular infiltration) were significantly better in the MTX+PEG group than in the MTX+saline group [22]. Only the abstract was opened (record retrieved through the OpenAlex single-record lookup, abstract rebuilt from its index); effect sizes, p values and the full text were not seen.

Direction

Reverse (protective) relative to an injury comparator. The comparison is PEG versus saline in methotrexate-injured rats, not PEG versus untreated healthy animals, and a PEG-only group is not described in the abstract. Methotrexate liver injury is the induced condition (Hard Rule 2): it is neither a drug effect of PEG 3350 nor a nutrient deficiency.

Mechanism

The authors state that PEG has antioxidant activity; a mechanism was not tested in the abstract opened, so it is a stated hypothesis only. Oral PEG 3350 is minimally absorbed [5], and the study bypassed the gut by intraperitoneal injection, so the route does not map onto the labeled oral laxative use.

Counter-evidence held on record

Counter-evidence on record Single rat study, one group of authors, injection route, high-toxicity model; no replication located and no oral administration. MDA is a lipid-peroxidation marker and is not a mitochondrial or ATP measurement, so this source does not support those entries. Framing caution This is not an oxidative-stress deficit and not a reason to expect or add antioxidants. It runs in the protective direction and in animals only; do not present it as a benefit of taking PEG 3350 orally.

Copper and Iron Balance

Copper and iron are assessed separately. Nothing here is counted twice.

Copper

Not graded — disclosed evidence gap

See study details

No PEG 3350 study measured copper or ceruloplasmin, and no copper claim for this drug was found.

Full detail and limits

What the grade means here: Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result. Ungraded

Limits on what this shows

  • Why no grade: Dual condition met: no Tier B or C source, and none of the claim pages opened mentions copper. Classification: likely genuine gap on the PubMed channel (two earlier listings returned no PEG laxative copper study), with secondary indexes unreachable and the revision-pass copper queries rate-limited.

Channels tried

WebFetch PubMed listing "polyethylene glycol 3350 copper": 3 records, all PEG used as a chemistry reagent (PMIDs 25575660, 26341133, 10942290). WebFetch PubMed listing "macrogol laxative copper OR ceruloplasmin": 10 records, all general copper and ceruloplasmin biology with no macrogol study. WebSearch mineral-absorption query (not copper-specific): no PEG-specific mineral paper. Revision pass: WebFetch OpenAlex search "polyethylene glycol 3350 copper": HTTP 429, not retrieved. WebFetch PubMed listing "polyethylene glycol laxative copper absorption": HTTP 429 via proxy, which asked that it not be refetched. Pashankar 2003 [6] and Worona-Dibner 2023 [7] were not reported to measure copper. Europe PMC, Semantic Scholar, Unpaywall, curl: blocked.

Revisit

Re-check with Europe PMC full-text search when reachable. Copper stays an independent entry and is not merged with Iron.

Gut Microbiome Risk

Each finding below is counted once, in this area only.

Gut microbiome risk: composition shifts in rodents at high PEG 3350 exposure, no human daily-dose data

Yellow — Low

See study details

In mice, PEG 3350 given in drinking water for days changed gut community composition and left a durable change after cessation; whether the labeled 17 g daily dose does this in people has not been studied in any source located.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. Yellow

Limits on what this shows

  • Negative and null findings: A search of PubMed listings for human studies of PEG laxatives and microbiota returned four records, all animal, review or bowel-prep work; no human daily-dose PEG 3350 microbiome study was located. The mouse exposures are high and not dose-translated to humans. Whether the shifts constitute a nutrient problem is not shown: no vitamin or mineral outcome was measured in these studies.
  • At-risk subgroups: Hypothesis only: people exposed to C. difficile (mouse finding [11]), and people with IBD or fragile microbial resilience (per an opinion review about bowel-prep PEG, [15], which is out-of-scope context and not carried onto this entry).

Regulatory status

The NF label states the polymer is not fermented by colonic microflora [2]. Neither label opened carries a microbiome warning [1], [2].

Population evidence

Tier B, drug-specific, animal. Tropini 2018 (Cell): germ-free Swiss-Webster mice colonized with human, mouse or defined microbiotas; 15% PEG 3350 (MiraLAX) for 6 days; the S24-7 family (nearly 50% of baseline abundance) showed apparent extinction, Bacteroidaceae rose from about 20% to about 60%, over 75% of final abundance was in taxa significantly altered two weeks after cessation, and alpha diversity stayed lower [10]. Tomkovich 2021 (mSphere): C57BL/6 mice, 15% PEG 3350 for 5 days left mice susceptible to C. difficile colonization lasting up to 30 days, whereas 1 day gave only transient colonization [11]. van der Wulp 2013: rats, PEG 7% in drinking water for 2 weeks, bile salt pool +51%, turnover -32%, Verrucomicrobia up and Firmicutes down; the PEG molecular weight is not stated in the abstract opened, so this is supporting evidence only [12].

Mechanism

Named and plausible: osmotic fluid load and accelerated transit alter the luminal environment, not substrate fermentation. Mechanism in humans at the labeled dose is not demonstrated.

Counter-evidence held on record

Counter-evidence on record The label statement that PEG 3350 is not fermented [2] and the absence of any human data argue against reading the mouse data as a human finding. Bowel-preparation PEG-electrolyte data (a high-volume, different formulation) were not used to support this grade. Framing caution Do not present this as a depletion or as a reason to take probiotics or supplements. It is a low-confidence animal signal about community composition, not a measured nutrient deficit.

Oxygen and ATP Output

Oxygen delivery and ATP production are assessed separately. Nothing here is counted twice.

Oxygen delivery/utilization

Not graded — disclosed evidence gap

See study details

No study tested oxygen-carrying capacity, arterial oxygenation or tissue oxygen delivery in PEG 3350 users; one pediatric cohort reported hemoglobin and hematocrit as unremarkable.

Full detail and limits

What the grade means here: Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result. Ungraded

Limits on what this shows

  • Why no grade: Dual condition met: no Tier B or C evidence for a signal, and no circulating oxygen-carrying claim (the iron claim is rebutted separately). Observation on record, not reassurance: the Pashankar 2003 abstract (n=83 children, mean 8.7 months, PEG 3350 in cohort), opened in the revision pass through the OpenAlex PMID lookup, states "All blood test results were normal, except for transient minimal alanine aminotransferase elevation unrelated to PEG therapy" [6]. That abstract text does not itself name hemoglobin or hematocrit; the earlier statement that they were among the reported measures rested on the first review full-text view and was not re-verified here. There was no comparator group, a normal blood panel is a null observation and not a graded signal, and oxygen utilization was not tested. Classification: partly tooling-limited.

Channels tried

WebFetch PubMed listing "polyethylene glycol laxative hemoglobin anemia": HTTP 429, not retrieved. Revision pass: WebFetch OpenAlex PMID lookup 12860787 (Pashankar 2003): abstract opened, see above. WebFetch PubMed listing "(macrogol OR polyethylene glycol 3350) AND (anemia OR hemoglobin) AND laxative": 3 records, none an oral PEG 3350 laxative hemoglobin study (two were bowel-preparation or phosphate-salt work, one a nanoparticle paper; titles only, not opened, not cited). Safety cohorts [6], [7], [8] read directly. WebSearch iron and vitamin query: no PEG-specific hemoglobin paper. curl channels and other indexes: blocked.

Revisit

Re-run the PubMed hemoglobin query; Hard Rule 2 applies if any outcome is found (anemia is not iron deficiency).

ATP production

Not graded — disclosed evidence gap

See study details

No study of cellular ATP synthesis or energy output with PEG 3350 was located, and no "low energy" claim for it was found.

Full detail and limits

What the grade means here: Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result. Ungraded

Limits on what this shows

  • Why no grade: Dual condition met: no verified Tier B or C source and no circulating ATP or energy claim in the pages opened. Independent of Mitochondrial burden and Oxygen delivery/utilization; they share only the same absence of evidence (see Overlap map). Classification: partly tooling-limited.

Channels tried

Same set as Mitochondrial burden: PubMed listing combining oxidative stress or mitochondrial (3 records, none on ATP), PubMed mitochondria query 429, one WebSearch with ATP in the query, Europe PMC and OpenAlex 429, curl channels 403.

Revisit

Search "macrogol" with "ATP" or "energy metabolism" when PubMed listings are available.

Claims checked and not supported

These circulate online for this medication. They are listed here only so they can be answered, never as findings, and they are not graded.

A claim with no supporting evidence is not necessarily disproven. Where evidence actually argues against a claim, that is stated below.

  • Iron: PEG blocks iron absorption and causes iron deficiency (independent entry, not merged with Copper)

    Where it comes from: Practitioner blog and clinic page [17], [18]; no citation

    Why it fails: No study located measured iron, ferritin or iron absorption in PEG 3350 users, and no mechanism for iron binding or loss appears in any source opened. Hemoglobin reported normal in a pediatric cohort [6] does not measure iron status, so it neither supports nor refutes the claim; the claim fails for lack of support at any tier.

  • Fat-soluble vitamins A, D, E, K depleted

    Where it comes from: Nutrition consultancy list grouping mineral oil, lactulose, MiraLAX and senna [17]; no citation

    Why it fails: No vitamin measurement in a PEG 3350 study was located. Pooling PEG with other laxatives is not a cohort test, and no mechanism from other agents is carried over (Hard Rule 6).

  • Vitamin B12, calcium and zinc depleted

    Where it comes from: Same page [17]; no citation

    Why it fails: No B12 or zinc measurement located. Serum calcium: no hypercalcemia in a 12-month PEG 3350 cohort [7], but a serum value is not a depletion marker either way; no support at any tier.

  • PEG blocks nutrient absorption in the small intestine, causing malnutrition and brain damage

    Where it comes from: Alternative-health site [18]; asserts an FDA link to neuropsychiatric events, not located in any source opened

    Why it fails: The NF label states no effect on active absorption or secretion of glucose or electrolytes [2]. No malnutrition outcome is reported in the safety cohorts [6], [7], [8]. No supporting study is cited.

  • PEG "decimates" gut bacteria like antibacterial soap, causing biotin, vitamin K and iodine deficiency

    Where it comes from: Same site [18]

    Why it fails: Mouse 16S data show composition shifts (Bacteroidaceae expansion, S24-7 loss, lower diversity), not sterilization [10], and no biotin, vitamin K or iodine measure exists for PEG 3350. The real, low-grade signal is the Gut microbiome risk yellow entry.

  • Antifreeze and brake-fluid chemical; brain damage from propylene glycol

    Where it comes from: Substack post [19]

    Why it fails: The one paper cited concerns propylene glycol, a different compound. Not a nutrient claim; listed because readers have met it.

  • Calcium and potassium depleted by laxatives

    Where it comes from: Depletion handbook [20]

    Why it fails: Its only laxative row is bisacodyl, a stimulant laxative; PEG is not listed. Stimulant-laxative findings are not borrowed (Hard Rule 6).

How the body handles this medication

Absorption
Minimally absorbed. A 2026 review reports urinary recovery of 0.28% (Pelham 2008), 0.01% (van Wijck 2012) and under 0.08% for PEGs above 4000 g/mol (Brady 1986); its authors note trace values may reflect low-molecular-weight impurities (USP permits up to 3%). Pelham 2008 itself could not be opened (403).[5], [4]
Metabolism and CYP450
No metabolism, CYP induction or CYP inhibition is described in any source opened. The two labels opened contain no CYP statement. This is an absence in the sources reached, not a verified negative; the FDA accessdata host was blocked.[1], [2], [4]
Elimination
Unabsorbed polymer leaves in stool. Per the NF label, complete recovery occurred in normal subjects while recovery in constipated patients was incomplete and highly variable. The absorbed trace is renally excreted per source [5].[2], [5]
Luminal and tubular handling
Osmotic agent that causes water to be retained with the stool. Not fermented by colonic microflora; "no effect on the active absorption or secretion of glucose or electrolytes." No renal tubular mechanism is described.[2], [4]
Renal and accumulation
OTC label: do not use with kidney disease except under a doctor's supervision. One case report shows systemic PEG 3350 absorption during ileus with raised intestinal permeability and mild osmotic nephropathy.[1], [9]
Interactions and identity
Documented interaction: starch-based swallowing thickeners lose viscosity (separate use, use xanthan-based thickener). No food, mineral or antacid interaction appears in sources opened. WHO DDD 10 g is defined for macrogol 4000.[1], [4], [3]

What the research says is worth watching

General information from the medication label and the studies above. It is not personal medical advice, and any change belongs with your prescriber.

  • Labs, conditional

    Serum sodium and osmolality

    Reasonable when PEG 3350 is escalated, used beyond the 7 days on the OTC label, or in ileus, kidney disease or frail older adults. Based on one case report and not a routine nutrient screen.

  • Renal

    Kidney function

    The OTC label advises against use with kidney disease without supervision [1]. Check creatinine in at-risk users before long-term use.

  • Fluid

    Stool volume and hydration

    Loose, watery stools are the drug's intended effect, not a nutrient finding. Persistent watery stools or dehydration signs warrant a dose review by the prescriber or pharmacist.

  • Timing and interactions

    Swallowing thickeners

    Starch-based thickeners lose viscosity with PEG [1], [4]; a xanthan-based thickener is the stated alternative. No mineral or antacid separation interval is documented in sources opened. Oral-medication timing rules apply to electrolyte-containing bowel preps, a different, out-of-scope formulation [16].

  • Special populations

    Pregnancy, kidney, pediatric

    The OTC label asks pregnant or breast-feeding users to consult a health professional [1]. Pediatric cohorts exist [6], [7]. No pediatric or pregnancy nutrient finding is graded.

  • Not recommended

    Supplements

    No nutrient reached a grade that supports supplementation. Do not add vitamins, minerals or probiotics on the basis of this dossier.

Overlap map, to prevent double counting

  • Mitochondrial burden

    Shares evidence with: Oxidative stress (searches only); ATP production

    Note: All three rest on the same single PubMed listing result set and the same blocked channels. Mitochondrial burden and ATP production remain one shared gap in the record. Oxidative stress is now graded yellow on a single rat paper [22] that measured malondialdehyde and cytokines, not mitochondrial or ATP endpoints, so it is not counted toward either of those entries; the three share only the same search result sets.

  • Oxidative stress

    Shares evidence with: None

    Note: Rests on one source, Acar 2022 [22] (rat, intraperitoneal). No other entry or white row draws on it.

  • Oxygen delivery/utilization

    Shares evidence with: Iron (white); Sodium; Phosphate

    Note: Pashankar 2003 [6] is the one cohort behind the hemoglobin observation and the normal electrolyte findings. Worona-Dibner 2023 [7] likewise backs the Sodium and Phosphate null findings. Cited per entry, but a reader should not count each citation as separate confirmation.

  • Pashankar 2003 safety [6] and long-term efficacy [14]

    Shares evidence with: Same investigators and center

    Note: Patient overlap between the two reports is unverified; treat as possibly one clinical population.

  • Gut microbiome risk

    Shares evidence with: White rows on bacterial "decimation" and biotin, vitamin K, iodine

    Note: The rebuttal of the "decimates bacteria" claim and the yellow entry both draw on Tropini 2018 [10]. Three rodent studies are three groups but one evidence type (rodent, high drinking-water PEG); not human confirmation.

  • Sodium; Phosphate

    Shares evidence with: PEG 4000 and PEG 3350 cohorts

    Note: Phosphate rests on a PEG 4000 cohort [13] (class extrapolation). Its hypernatremia mention is not counted toward Sodium.

  • Copper; Iron

    Shares evidence with: None

    Note: Independent. They share only the consumer pages audited for claims. No source supports either.

All references used above
  1. MiraLAX (polyethylene glycol 3350) OTC Drug Facts label, Bayer HealthCare. Tier A, regulatory label. — Label PDF via DailyMed. Contains no pharmacokinetic section.
  2. Polyethylene Glycol 3350 NF, powder for oral solution, DailyMed label. Tier A, regulatory label. — Clinical pharmacology: osmotic agent, not fermented by colonic microflora, no effect on active absorption or secretion of glucose or electrolytes. Bulk NF product label, not the MiraLAX brand.
  3. WHO Collaborating Centre for Drug Statistics Methodology, ATC/DDD Index, A06AD15 macrogol (page updated 2026-01-20). — DDD 10 g, oral; DDD refers to macrogol 4000.
  4. Polyethylene Glycol, StatPearls. Tier B, established pharmacology reference. — Mechanism, minimal absorption, starch-thickener interaction, reference to hyponatremic seizure after bowel preparation (different formulation).
  5. Oral absorption of high molecular weight polyethylene glycols: mechanistic, safety and regulatory insights. Frontiers in Drug Safety and Regulation, 2026. Review (Tier B/C secondary). — Source for Pelham 2008, van Wijck 2012 and Brady 1986 urinary recovery figures; those primary papers were not opened. Author list not captured. DOI 10.3389/fdsfr.2026.1851318.Pelham 2008 (Wiley, DOI 10.1111/j.1365-2036.2008.03727.x) could not be opened: 403. Figures are cited through this review only.
  6. Pashankar DS, Loening-Baucke V, Bishop WP. Safety of polyethylene glycol 3350 for the treatment of chronic constipation in children. Arch Pediatr Adolesc Med, 2003. Tier A. PMID 12860787. — Prospective observational, n=83 children, mean 8.7 months (3 to 30), PEG 3350 in cohort. Hemoglobin, hematocrit, electrolytes, BUN, creatinine, osmolality, albumin, liver enzymes normal except transient ALT elevation. Vitamins, iron, copper, zinc not measured.
  7. Worona-Dibner L, Vazquez-Frias R, Valdez-Chavez L, Verdiguel-Oyola M. Efficacy, safety and acceptability of PEG 3350 without electrolytes vs magnesium hydroxide in children 6 months to 18 years. Rev Gastroenterol Mex (English Ed), 2023. Tier A. — Open-label randomized trial, n=83 (41 PEG 3350, 42 magnesium hydroxide), 12 months. No severe biochemical adverse events; no hypermagnesemia, hypomagnesemia, hypercalcemia or hypophosphatemia.
  8. McGraw T. Safety of polyethylene glycol 3350 solution in chronic constipation: randomized, placebo-controlled trial. Clin Exp Gastroenterol, 2016. Tier A (author as listed on the page). DOI 10.2147/CEG.S111693. — n=65 (31 PEG 3350, 34 placebo), 14 days treatment, 17 g daily. AEs 48.4% versus 55.9%; no serious AEs. Electrolytes, hemoglobin, iron and vitamins not reported in the text opened.
  9. Tucker BM, Pirkle JL, Stefi E, Sheikh-Hamad D, DuBose T. Iso-osmolar hyponatremia from polyethylene glycol. Clin Kidney J, 2021;14(2):715-719. Tier B, case report. DOI 10.1093/ckj/sfaa087. — One patient, PEG 3350 without electrolytes.
  10. Tropini C, Moss EL, Merrill BD, et al. Transient osmotic perturbation causes long-term alteration to the gut microbiota. Cell, 2018. Tier B, mouse. — Gnotobiotic and humanized mice, 15% PEG 3350 (MiraLAX) for 6 days; opened via the PMC copy.
  11. Tomkovich S, Taylor A, King J, et al. An osmotic laxative renders mice susceptible to prolonged Clostridioides difficile colonization and hinders clearance. mSphere, 2021. Tier B, mouse. DOI 10.1128/msphere.00629-21. — C57BL/6 mice, 15% PEG 3350 for 1 or 5 days.
  12. van der Wulp MY, Derrien M, Stellaard F, et al. Laxative treatment with polyethylene glycol decreases microbial primary bile salt dehydroxylation and lipid metabolism in the intestine of rats. 2013. Tier B, rat. PMID 23868407. — PEG 7% in drinking water, 2 weeks. Abstract opened through PubMed; PEG molecular weight not stated there. Journal inferred from DOI prefix (Am J Physiol Gastrointest Liver Physiol, 10.1152/ajpgi.00375.2012); full text returned 403.Molecular weight unconfirmed: used as supporting evidence only.
  13. Bae SH. Long-term safety of PEG 4000 in children with chronic functional constipation: a biochemical perspective. Korean J Pediatr, 2010;53(7). Tier C for this drug. DOI 10.3345/kjp.2010.53.7.741. — n=100 children, mean 16.93 months. Hyperphosphatemia in 10% on initial testing; vitamins, iron and zinc not measured.Cohort excluded PEG 3350 (PEG 4000 studied). Class extrapolation only.
  14. Pashankar DS, Bishop WP, Loening-Baucke V. Long-term efficacy of polyethylene glycol 3350 for the treatment of chronic constipation in children with and without encopresis. Clin Pediatr, 2003;42(9):815-819. Tier A (efficacy). — n=74, mean 8.4 months. Abstract reports no electrolyte, vitamin or mineral measurements.
  15. Melgaco ACC, Alves AF, Pessoa WFB. Polyethylene glycol-based bowel preparation and gut dysbiosis: clinical implications beyond colon cleansing. World J Gastroenterol, 2026. Opinion review. — Context only. Bowel-prep PEG formulations, a different formulation; not used to support any grade.Out of scope formulation (high-volume PEG-electrolyte bowel prep).
  16. Polyethylene glycol 3350 with electrolytes for oral solution (bowel preparation), prescribing information summary, Drugs.com. Regulatory text, out-of-scope formulation. — Used only for the labeled oral-medication timing rule and the statement that oral PEG 3350 is poorly absorbed.PEG-electrolyte bowel prep is out of scope for this dossier; context only.
  17. Top 10 medications that deplete the body of essential nutrients, YK Nutrition consultations (2016). Tier D. — Source of the vitamin and mineral depletion claims; no citations on the page.Tier D: claim origin only, supports nothing.
  18. The role of MiraLAX laxative in autism, dementia, Alzheimer, GutSense. Tier D. — Source of the nutrient-blocking, bacterial decimation and neurotoxicity claims.Tier D: claim origin only, supports nothing.
  19. MiraLAX is allergy-inducing polyethylene glycol, Denutrients Substack. Tier D. — Antifreeze and propylene glycol conflation.Tier D: claim origin only, supports nothing.
  20. Medication-induced nutrient depletion, Riordan Clinic handout. Tier D. — Lists bisacodyl laxatives only; PEG not listed.Tier D: claim origin only, supports nothing.
  21. What are the long-term side effects of MiraLAX, Biology Insights. Tier D. — Consumer summary stating no meaningful electrolyte or nutritional changes at standard dose and that human microbiome effect is unknown; used only to confirm the audit of what circulates.Tier D: supports nothing.
  22. Acar H, Sorgun O, Bora ES, Erbas O, et al. Antifibrotic preventive effect of polyethylene glycol (PEG) 3350 in methotrexate-induced hepatoxicity model. Acta Cirurgica Brasileira, 2022. Tier B, rat. PMID 35894304. DOI 10.1590/acb370507. — 30 male rats (10 normal, 20 methotrexate), PEG 3350 30 mg/kg/day or saline intraperitoneally for two weeks. Lower TGF-beta, plasma and liver MDA, TNF-alpha, ALT, pentraxin-3 and better histology in MTX+PEG than MTX+saline. Opened as an abstract through the OpenAlex single-record lookup (api.openalex.org/works/doi:10.1590/acb370507), reconstructed by the fetch tool from the index; full text, effect sizes and the conclusions paragraph not seen.Full text not opened (doi.org, SciELO and PubMed record pages were blocked); intraperitoneal route, not oral. Supporting yellow only.