Propranolol Safety During Breastfeeding
Propranolol is safe to use while breastfeeding, as it transfers into breast milk in very small amounts that are far below therapeutic infant doses, and there is no reason to advise women receiving propranolol to avoid breastfeeding.
Evidence for Safety
The FDA drug label confirms that propranolol is excreted in human milk but recommends caution rather than contraindication when administered to nursing women 1
Research demonstrates that breast milk concentrations of propranolol are only 40-64% of peak maternal plasma levels, with an estimated maximum infant exposure of only 21 micrograms per 24 hours when the mother takes 40 mg four times daily—considerably less than therapeutic infant doses 2
A clinical study of a hypertensive woman treated with propranolol 40 mg daily throughout pregnancy and lactation found milk:plasma ratios less than 1, with estimated daily infant intake of only 3 micrograms via breast milk, concluding there is no reason to advise women receiving propranolol to avoid breastfeeding 3
Pharmacokinetic Considerations
Propranolol has high protein binding (>90%), which limits its transfer into breast milk 4
Peak concentrations in breast milk occur 2-3 hours after maternal dosing, though the absolute amounts remain clinically insignificant 2
Beta-blockers with high protein binding like propranolol have lower milk-to-plasma ratios compared to those with low protein binding, making them safer choices for breastfeeding mothers 4
Important Clinical Caveats
Monitor infants for bradycardia, hypoglycemia, or respiratory depression if mothers are taking propranolol at parturition, as the FDA label notes these effects have been reported in neonates whose mothers received propranolol during delivery 1
Special consideration should be given when mothers are taking multiple antihypertensive medications from different drug classes, as theoretical additive effects on the infant could occur, though clinical reports remain limited 5
All medications transfer into breast milk to some degree, but the key consideration is whether the amount poses clinical risk—with propranolol, the transferred dose is far below therapeutic levels 6