Is clonazepam safe for a mother who is breastfeeding her infant?

Clonazepam Use During Breastfeeding

Clonazepam can be used during breastfeeding with appropriate infant monitoring, as it transfers into breast milk in low amounts and adverse effects in breastfed infants are rare.

Evidence-Based Recommendation

The FDA drug label explicitly states that "clonazepam can pass into breast milk" and recommends that "you and your healthcare provider should decide how you will feed your baby while you take clonazepam" 1. However, this cautious language must be interpreted alongside clinical evidence showing actual safety in practice.

The 2020 Association of Anaesthetists guideline on sedation in breastfeeding women provides specific guidance on benzodiazepines: Shorter-acting benzodiazepines like lorazepam, midazolam, and temazepam are preferred over diazepam (which has a prolonged half-life active metabolite). While the guideline focuses on single-dose procedural use, it notes that diazepam "is known to be transferred in breast milk in significant levels" 2. Clonazepam, though not extensively discussed in this procedural guideline, shares similar benzodiazepine properties.

Pharmacokinetic Data

Research evidence demonstrates reassuring transfer levels:

• A 2022 systematic review from the ILAE Women Task Force found that clonazepam results in "very low concentrations" in breastfed infants, approximately 10% or less of maternal serum concentrations 3

• A 2021 Japanese study measuring benzodiazepine concentrations in breast milk found that for all benzodiazepines tested (including clonazepam), the milk-to-plasma (M/P) ratios were <1 and the relative infant dose (RID) values were <10%, which is considered the safety threshold. No abnormalities were found in breastfeeding infants whose mothers were receiving these medications 4

Clinical Safety Evidence

The most compelling evidence comes from prospective clinical studies:

• A 2012 prospective cohort study of 124 mothers taking benzodiazepines during breastfeeding found adverse outcomes (specifically sedation) in only 1.6% (2 of 124) of infants. The study concluded: "This study supports the continued recommendation to initiate breastfeeding while taking benzodiazepines postpartum" 5

• A 1994 comprehensive review noted that "the levels detected in breast milk are low; therefore, the suckling infant is unlikely to ingest significant amounts of the drug" 6

Important Caveats and Monitoring

There is conflicting guidance in the literature that requires clarification:

• A 2013 Italian review states that "the continue use of clonazepam and diazepam are contraindicated during breastfeeding" 7. However, this appears to be an outlier recommendation not supported by the pharmacokinetic data or the prospective clinical studies

• The key distinction is between single/intermittent dosing versus chronic continuous use. The concern with continuous clonazepam relates to potential drug accumulation due to its longer half-life compared to shorter-acting benzodiazepines

If clonazepam is used during breastfeeding, monitor the infant for:

• Excessive sedation or drowsiness
• Poor feeding or decreased alertness
• Respiratory depression (rare but serious)
• Hypotonia (decreased muscle tone)

Risk is higher in:

• Premature infants
• Neonates (especially <1 month old)
• Infants with hepatic or renal impairment
• When mother is taking multiple CNS depressants concurrently 6, 5

Clinical Decision Algorithm

1. Assess maternal need: Is clonazepam medically necessary? Can a shorter-acting benzodiazepine be substituted?

2. Assess infant risk factors: Is the infant full-term, healthy, >1 month old?

3. If proceeding with breastfeeding on clonazepam:

   • Use the lowest effective maternal dose
   • Monitor infant closely for sedation, feeding difficulties, and developmental milestones
   • Consider timing feeds to avoid peak milk concentrations (though this is less practical with chronic dosing)
   • Avoid co-administration of other CNS depressants when possible

4. Counsel mother: The benefits of breastfeeding are substantial 8, 9, and the actual risk of adverse effects appears low based on clinical studies. However, vigilant monitoring is essential.

The 2005 AAP guideline emphasizes that "most medications that women who are breastfeeding might take are compatible with breastfeeding" and recommends consulting specialized databases like LactMed for specific guidance 8.

In summary, while clonazepam does transfer to breast milk, the clinical evidence suggests that breastfeeding can continue with appropriate infant monitoring, particularly in healthy, full-term infants beyond the neonatal period. The decision should weigh the well-established benefits of breastfeeding against the low but real risk of infant sedation, with individualized monitoring based on infant age and health status.