May 27 2022


Cimetidine passes to the baby through breast milk in an amount considerably lower than the therapeutic dose directly applicable to the infant, so it is not expected direct harm to the child due to its use by the mother, especially in children over eight weeks old.

An exclusively breastfed infant whose mother take 1000 mg per day of cimetidine could ingest between 0.74 and 0.90 mg/kg/day of the substance, far away from the therapeutic dose in infants (5 - 10 mg/kg).

Cimetidine can cause elevated prolactin, galactorrhea and gynecomastia in non-lactating women, although its use is not an obstacle during breastfeeding.

The existence of safer alternatives, without the added problem of enzyme inhibition on CYP3A4, make it advisable not to use this medication during breastfeeding.

Warning of the manufacturer:

Animal studies and clinical evidence have shown no risk on the use of cimetidine during pregnancy or lactation, but studies in animals and humans show that cimetidine crosses the placenta and is excreted in breast milk.

The use of cimetidine should be avoided during pregnancy and lactation unless considered necessary.