LACTOLOGY FOUNDATION

Antacids in ATC class A02AX (“antacids, other combinations”) used during lactation include mainly bismuth‑containing preparations and sucralfate; overall, sucralfate appears relatively compatible with breastfeeding, whereas bismuth subsalicylate–containing products are generally discouraged because of theoretical salicylate toxicity and Reye syndrome risk in the infant.

Pharmacological overview

Antacids from class A02AX are combination products that usually pair local gastroprotective agents (such as bismuth salts or sucralfate) with antacids or other mucosal protectants, and are indicated for peptic ulcer disease, gastritis, functional dyspepsia or diarrhea, depending on composition.
Bismuth salts act mainly by coating the gastric and duodenal mucosa, stimulating local prostaglandin and bicarbonate secretion, and exerting a mild antimicrobial effect against Helicobacter pylori, while sucralfate forms a viscous, adhesive complex that binds to ulcer bases and protects them from acid and bile.
Systemic absorption is very low for elemental bismuth and for sucralfate as a polymer, but can be substantially higher for the salicylate moiety in bismuth subsalicylate, which is well absorbed and systemically bioavailable.

Bismuth‑containing antacids

Multiple bismuth salts are used clinically, including bismuth subcitrate, subnitrate, subsalicylate and various organic complexes, all formulated primarily for ulcer therapy or acute diarrhea.
Elemental bismuth is absorbed from the gastrointestinal tract at well under 1% of the oral dose, but bismuth subsalicylate allows extensive absorption of the salicylate fraction (over 90%), resulting in meaningful maternal systemic exposure to salicylate.

Clinically relevant maternal adverse effects from chronic or high‑dose bismuth exposure include neurotoxicity, blackening of tongue and stool, and, with salicylate‑containing preparations, the usual spectrum of salicylate toxicity.
In the breastfed infant, theoretical bismuth toxicity could manifest as discoloration of tongue and stool, neuromuscular irritability and, in the case of subsalicylate, a potential contribution to Reye syndrome in the setting of viral infection and fever, although well‑documented cases via breast milk have not been reported.

Because salicylates are known to enter human milk (typical relative infant doses around or below 1% for acetylsalicylic acid) and are associated with Reye syndrome when given directly to children, several authorities recommend that breastfeeding women avoid bismuth subsalicylate if alternative antidiarrheals (e.g. loperamide or kaolin‑pectin) are available.
Non‑salicylate bismuth salts without systemic absorption are theoretically less risky for the infant, but robust lactation safety data are lacking, so prolonged or repeated use during breastfeeding is generally discouraged in favor of better‑studied options.

From a toxico‑lactological perspective, bismuth‑containing antacids are best placed in a cautious category (roughly equivalent to a high‑risk lactation category such as III) because milk levels may approximate or exceed maternal plasma for salicylates, and clear safety margins for chronic exposure have not been defined.
If a short course of bismuth is used, careful infant monitoring for gastrointestinal symptoms, unusual bruising, behavioral changes or signs of viral illness with altered consciousness is prudent, and breastfeeding interruption can be considered when high doses or prolonged regimens are planned.

Sucralfate

Sucralfate is an aluminum‑containing gastroprotective agent that forms a cross‑linked complex adhering to ulcerated or inflamed mucosa and also binds bile acids, making it useful in peptic ulcers, reflux esophagitis and bile reflux gastritis.
Each standard tablet contains several hundred milligrams of aluminum as part of the sucralfate complex, but gastrointestinal absorption of intact sucralfate is minimal, leading to only very small systemic aluminum exposure in individuals with normal renal function.

Acute aluminum toxicity in adults receiving sucralfate at therapeutic doses is rare, though tissue aluminum accumulation may occur with prolonged therapy, particularly in patients with reduced glomerular filtration.
Late‑onset aluminum neurotoxicity and osteotoxicity are well documented in chronically exposed renal failure patients and are therefore a theoretical concern for neonates exposed via breast milk if maternal therapy is long term and maternal or infant renal function is impaired.

Despite the aluminum content, most lactation‑oriented sources consider sucralfate compatible with breastfeeding because of its poor absorption and the expectation of negligible transfer into milk, with E‑lactation classifying it as “compatible, low risk” and LactMed noting that no special precautions are usually required.
Official drug references still recommend routine caution, acknowledging that many medicines can appear in milk, but they do not contraindicate sucralfate in nursing women.

In a toxico‑lactological framework, sucralfate may be placed in an intermediate risk category (similar to category III in your internal system) because long‑term high‑dose use could, in theory, lead to significant infant aluminum exposure in the presence of renal immaturity, even if short‑term therapy appears safe.
Therefore, short‑term treatment for gastroduodenal disease in a healthy breastfeeding mother with a term infant is acceptable with simple clinical monitoring, while prolonged therapy in mothers of preterm infants or infants with renal impairment warrants individualized risk‑benefit assessment and consideration of alternative agents.

Comparative toxico‑lactological assessment

In everyday clinical practice, alternative approaches for gastritis or dyspepsia during lactation (such as simple non‑aluminum antacids, H2‑receptor antagonists or proton pump inhibitors with well‑characterized lactation safety profiles) should generally be preferred to bismuth combinations, reserving sucralfate for situations where its mucosal protective effect offers a clear therapeutic advantage.
Whenever a A02AX agent is considered for a breastfeeding woman, it is important to individualize the decision based on maternal indication, expected treatment duration, infant age and renal function, and to ensure structured follow‑up for any signs of gastrointestinal, neurologic or hepatic toxicity in the infant.