From the Guidelines
Metoprolol is considered safe to use during lactation, with limited safety data indicating a likely low risk, as noted in the 2025 study published in Circulation 1. The amount of metoprolol that passes into breast milk is expected to be relatively small, although the exact Relative Infant Dose (RID) is not specified in the provided evidence. However, based on the information given, metoprolol tartrate has limited safety data but is likely to be low risk, similar to carvedilol, which is also a beta-blocker. Key points to consider when using metoprolol during lactation include:
- Monitoring the infant for potential side effects, although these are rare
- Using the lowest effective dose to minimize exposure
- Coordinating the timing of doses with breastfeeding to reduce infant exposure, if possible
- Weighing the benefits of maternal treatment against potential risks to the infant, as with any medication during lactation. It's also important to note that other medications, such as labetalol, have more established safety profiles during lactation, with a specified RID of 3.6% 1, but metoprolol can still be considered a viable option when beta-blocker therapy is indicated.
From the FDA Drug Label
Metoprolol is excreted in breast milk in a very small quantity. An infant consuming 1 liter of breast milk daily would receive a dose of less than 1 mg of the drug Metoprolol appears to be safe to use during lactation as the amount excreted in breast milk is very small, with an infant receiving less than 1 mg of the drug per liter of breast milk consumed 2. Key points:
- Metoprolol is excreted in breast milk in a very small quantity
- The estimated dose received by an infant is less than 1 mg per liter of breast milk consumed However, it is essential to consult a healthcare professional for personalized advice on using metoprolol during lactation.
From the Research
Metoprolol Use During Lactation
- Metoprolol is a beta-blocker used to treat various cardiovascular conditions, and its safety during lactation has been evaluated in several studies 3, 4, 5, 6.
- A systematic review and meta-analysis found a probable risk of hypoglycemia and possible risk of bradycardia in neonates exposed to beta-blockers, including metoprolol, during pregnancy or lactation 3.
- A cohort study compared the effects of metoprolol and bisoprolol on fetal growth and postnatal symptoms, and found that long-term intrauterine exposure to these beta-blockers may increase the risk of being born small-for-gestational-age 4.
- A review of beta-blockers and lactation found that metoprolol is one of the most commonly used agents in the treatment of hypertension, and that its safety in lactating women has been evaluated in several studies 5.
- A pharmacokinetic study found that the relative infant exposure to metoprolol through breast milk was less than 1.0% of the maternal weight-adjusted dose, suggesting that metoprolol is safe to use during lactation 6.
Pharmacokinetics and Safety
- The pharmacokinetics of metoprolol during pregnancy and lactation have been evaluated in several studies, and found to be affected by pregnancy-induced changes in drug metabolism 6.
- Metoprolol is generally well tolerated, and its beta 1-selectivity may facilitate its administration to certain patients, such as asthmatics and diabetics, in whom non-selective beta-blockers are contraindicated 7.
- The most frequently reported side effects of metoprolol include temporary fatigue, dizziness, and headache 7.
Clinical Implications
- Clinicians who prescribe metoprolol during pregnancy or lactation should be prepared to make aggressive changes in dosage or consider using an alternate beta-blocker if inadequate clinical responses are encountered 6.
- Close monitoring of neonates exposed to metoprolol during pregnancy or lactation is recommended, particularly for signs of hypoglycemia and bradycardia 3, 4.