Is cetirizine (Reactine) safe for a breastfeeding mother and her healthy full‑term infant?

Is Reactine (Cetirizine) Safe for Breastfeeding?

Yes, cetirizine (Reactine) is safe for breastfeeding mothers and their healthy full-term infants, with minimal drug transfer into breast milk and no reported adverse effects in nursing infants. 1, 2

Primary Recommendation

The European Respiratory Society recommends loratadine or cetirizine as preferred antihistamines during breastfeeding, as they have been most extensively studied. 1 This represents the highest-quality guideline evidence available, making cetirizine a first-line choice for breastfeeding mothers requiring antihistamine therapy.

Evidence Supporting Safety

Drug Transfer and Infant Exposure

• The most recent 2024 human lactation study demonstrates that cetirizine transfer into breast milk is low, with a weight-adjusted relative infant dose (RID) of only 1.9%, well below the 10% safety threshold. 2
• Maximum milk concentrations occur approximately 2.4 hours after maternal intake, with an average concentration of 16.8 μg/L and a half-life in milk of 7.0 hours. 2
• An earlier 2021 study confirmed minimal transfer with an RID of 1.77% at 24 hours, with no adverse effects reported in infants. 3

Clinical Safety Profile

• No severe adverse events have been reported in breastfed infants whose mothers used cetirizine. 2
• The dose received by infants through breast milk is substantially lower than known safe doses when cetirizine is administered directly to infants. 4

Important Caveats and Monitoring

Theoretical Milk Supply Concerns

• Antihistamines may theoretically reduce milk production, though this has not been demonstrated clinically with cetirizine. 1 Monitor for any changes in milk supply, particularly in the early postpartum period when lactation is being established.

Renal Function Considerations

• In mothers with moderate renal impairment, the cetirizine dose should be halved. 1
• Cetirizine should be avoided entirely in mothers with severe renal impairment. 1

Dosing Strategy

• Advise mothers to take cetirizine just after breastfeeding or just before the infant's longest sleep period to minimize infant exposure during peak milk concentrations. 5

Contrast with FDA Drug Label

A critical caveat: The FDA drug label for cetirizine states "if breast-feeding: not recommended," 6 which directly contradicts the current clinical guideline evidence and recent pharmacokinetic studies. This discrepancy reflects the FDA's conservative labeling approach in the absence of manufacturer-sponsored studies, rather than actual safety concerns. The European Respiratory Society guideline 1 and two high-quality human lactation studies 3, 2 provide stronger, more recent evidence supporting cetirizine's safety during breastfeeding.

Clinical Decision Algorithm

1. First-line choice: Prescribe cetirizine or loratadine as preferred antihistamines for breastfeeding mothers. 1
2. Assess renal function: Adjust dose if moderate impairment exists; avoid if severe impairment. 1
3. Optimize timing: Instruct mother to take medication after nursing or before infant's longest sleep. 5
4. Monitor milk supply: Watch for any reduction in milk production, though clinically unlikely. 1
5. Reassure mother: Explain that despite FDA labeling, current evidence strongly supports safety. 1, 2

Common Pitfalls to Avoid

• Do not discontinue breastfeeding based solely on the FDA drug label warning, as this contradicts current clinical evidence and would deprive the infant of breastfeeding's well-established benefits. 5, 4
• Do not advise mothers to "pump and dump" when using cetirizine, as the drug transfer is minimal and poses no significant risk. 2
• Do not prescribe first-generation antihistamines (such as diphenhydramine) as alternatives, as they have greater sedating effects and less favorable safety profiles compared to cetirizine. 1