Available data suggest that tacrolimus quantities ingested by an infant are small and probably not affect the baby. However,tacrolimus is a cytotoxic drug, that can interfere with the development of the infant and would require blood level control to evaluate the risk. It is estimated that, at normal doses, the baby can ingest up to 0.5% of the weight-adjusted maternal dose.
Topically administered tacrolimus is of less danger and concentrations are probably at low risk. It is advisable, in these cases, avoid contact of the baby with treated skin, and maintain clean scrupulously nipples area during feeding.
Warning of the manufacturer:
Human data demonstrate that tacrolimus is excreted in breast milk. As it is not possible to rule out adverse effects on the newborn, women should not breast-feed while undergoing treatment with this medicine.