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Macrogol (ATC A06AD15) is an osmotically acting laxative based on polyethylene glycol that shows minimal systemic absorption, and current evidence supports its compatibility with breastfeeding when used at therapeutic doses under medical supervision.medpedia.framar+4

Overview

Macrogol (polyethylene glycol, PEG) in ATC class A06AD15 is an oral osmotic laxative used for treatment of constipation and for bowel preparation before colonoscopy and other endoscopic procedures. It increases stool water content by retaining water in the intestinal lumen, leading to softer stools and stimulation of bowel movements, with onset of action typically within 1–2 hours after ingestion at bowel‑prep doses and after several days of once‑daily dosing in chronic constipation. Macrogol 3350 and 4000 are poorly absorbed, metabolically inert polymers, and up to 85–99% of an ingested dose is excreted unchanged in feces, which is the key toxicological and lactational advantage of this group. In clinical practice macrogol is used short term for acute constipation, long term in chronic functional constipation including in neurological disease, and at high doses for complete colonic cleansing before colonoscopy.drugs-porphyria+5

Maternal toxicity

At usual laxative doses macrogol has a favorable safety profile in adults, with systemic toxicity considered low due to minimal gastrointestinal absorption and lack of metabolism. Common adverse effects include abdominal pain, bloating, flatulence, nausea, vomiting, diarrhea, and abdominal distension, which reflect its pharmacological osmotic action. At high or prolonged doses, particularly in bowel‑prep regimens, excessive fluid loss may lead to dehydration and electrolyte disturbances, and for this reason colonoscopy solutions typically contain added electrolytes to reduce the risk. Serious hypersensitivity reactions are rare but reported: urticaria, edema, and anaphylaxis have been described with macrogol‑containing solutions, including reactions to PEG used as an excipient in various medicinal and cosmetic products. In elderly patients and those with comorbidities predisposing to electrolyte imbalance (e.g. heart failure, renal impairment, diuretic therapy), macrogol should be used under medical supervision with monitoring for diarrhea, dehydration and serum electrolytes; caution is advised in ulcerative colitis and other inflammatory bowel diseases because of increased perforation risk.wikipedia+6

Infant risk

Pharmacokinetically, polyethylene glycol of the macrogol 3350/4000 type has extremely low oral bioavailability and high molecular weight, so clinically significant transfer into breast milk is considered unlikely. Available information indicates no direct measurements of PEG levels in human milk, but experts and professional associations classify macrogol as compatible with breastfeeding, emphasizing negligible systemic absorption in the mother and, consequently, negligible exposure of the infant. Because macrogol is not appreciably absorbed from the maternal gut, any minute quantity that might reach milk would also not be absorbed from the infant’s gastrointestinal tract, further reducing risk of systemic effects in the breastfed child. No specific adverse reactions in breastfed infants have been linked causally to maternal macrogol therapy in the available literature; routine clinical observation of the infant is considered sufficient, without a need for dose‑timing relative to feeds.e-lactation+3

Clinical use in lactation

Guidelines and expert reviews recommend macrogol as a first‑line pharmacological option for constipation during lactation because of its non‑absorbed mechanism and reassuring clinical experience. Non‑absorbed laxatives in general are considered preferable in breastfeeding women, and macrogol is often favored over lactulose due to faster onset of action and fewer complaints of flatulence. Typical adult doses for macrogol 3350 or 4000 used as laxatives range from 10–20 g once daily (macrogol 4000) or around 17 g once daily (macrogol 3350), with adjustment according to response and product‑specific recommendations; these regimens can be continued in breastfeeding mothers when clinically indicated, while monitoring for maternal diarrhea and hydration status. Short‑term high‑volume regimens for bowel preparation (e.g. 238 g PEG in 2 L fluid) are also considered compatible with breastfeeding; in practice, some clinicians may advise feeding just before starting the preparation and resuming on demand afterwards, without prolonged interruption. Overall, in the absence of maternal contraindications such as bowel perforation, obstruction, toxic megacolon or severe inflammatory bowel disease, macrogol therapy does not require routine cessation of breastfeeding and can be integrated into management of constipation in nursing women.nhs+6

Evidence summary

The lactation safety profile of macrogol is supported primarily by pharmacokinetic principles (minimal absorption and high molecular weight) and expert consensus rather than by large controlled studies measuring drug levels in milk or infant outcomes, so the overall evidence can be described as “reassuring based on pharmacokinetic data and clinical experience, but with limited direct milk concentration studies”. Several professional sources and specialized lactation databases explicitly classify polyethylene glycol/macrogol as compatible with breastfeeding and recommend it as a preferred or first‑line laxative during lactation, reflecting moderate clinical experience and an absence of reported serious infant toxicity. Obstetric and gastroenterology literature on constipation in pregnancy and lactation likewise suggest macrogol as first‑line treatment in pregnant women and as a preferred agent during breastfeeding, emphasizing its faster efficacy and benign systemic profile compared with other laxatives. Taken together, these data support continued breastfeeding during maternal macrogol therapy, with standard clinical vigilance but without special restrictions or routine need for milk expression and discard.pubmed.ncbi.nlm.nih+4