What beta blockers (beta-adrenergic blocking agents) are safe to use during breastfeeding?

Beta-Blockers Safe in Breastfeeding

Propranolol and metoprolol are the safest beta-blockers for breastfeeding mothers, while atenolol should be avoided due to high milk concentrations and reported clinically significant bradycardia in breastfed infants. 1, 2

Recommended Beta-Blockers

Propranolol (First Choice)

• Propranolol is excreted in human milk but appears safe for breastfeeding, with milk:plasma ratios less than 1 and estimated daily infant intake of only approximately 3 micrograms. 3
• The FDA label states caution should be exercised but does not contraindicate breastfeeding, and clinical evidence from a hypertensive woman treated throughout pregnancy and lactation showed no complications. 2, 3
• There appears to be no reason to advise women receiving propranolol to avoid breastfeeding based on available evidence. 3

Metoprolol (Preferred Alternative)

• Metoprolol has favorable pharmacokinetics for breastfeeding, with milk:plasma ratios between 2.0-3.1, but infant plasma concentrations remain negligible or below detection limits. 4
• Exposure to the infant can be minimized by timing nursing at least 3-4 hours after maternal dose intake. 4
• Beta-blockers with high protein binding (like metoprolol) appear to be safe treatments for hypertension in nursing mothers. 5

Beta-Blockers to Avoid

Atenolol (Contraindicated)

• Atenolol should be avoided during breastfeeding due to high milk:plasma ratios (1.1-3.1) and concerning clinical effects. 4
• The FDA label explicitly warns that clinically significant bradycardia has been reported in breastfed infants, and premature infants or those with impaired renal function are at higher risk for adverse effects including hypoglycemia and bradycardia. 1
• Atenolol is excreted in human breast milk at a ratio of 1.5 to 6.8 compared to plasma concentration, representing substantial infant exposure. 1
• Beta-blockers with low protein binding (like atenolol) should be avoided based on systematic review evidence. 5

Clinical Algorithm for Selection

When prescribing beta-blockers to breastfeeding mothers:

1. Choose propranolol as first-line agent for its established safety profile and minimal infant exposure 3

2. Use metoprolol as alternative if propranolol is contraindicated, instructing mothers to nurse 3-4 hours after dosing 4

3. Avoid atenolol entirely due to documented bradycardia risk in infants and high milk transfer 1

4. Monitor all breastfed infants for signs of beta-blockade including bradycardia, hypoglycemia, and respiratory depression, particularly in neonates and premature infants 1

Important Caveats

• Most commonly used drugs are relatively safe for breastfed babies, with doses received via milk generally much less than known safe doses given directly to infants. 6
• The fundamental principle is risk-benefit assessment, choosing drugs that are well-studied with minimal milk transfer and no apparent infant health risk. 7
• Neonates born to mothers receiving beta-blockers at parturition require adequate monitoring facilities at birth. 1, 2