Is it safe for a lactating woman to take Montelukast (montelukast) and Levocetirizine (levocetirizine) while breastfeeding?

Montelukast and Levocetirizine During Breastfeeding

Both montelukast and levocetirizine are compatible with breastfeeding, with montelukast having stronger supporting evidence showing only 1% excretion into breast milk and levocetirizine being acceptable though with less accumulated safety data. 1, 2

Montelukast Safety Profile

Montelukast is strongly recommended as compatible with breastfeeding based on multiple guideline societies and extensive pharmacokinetic data. 1

• Only approximately 1% of the maternal dose passes into breast milk, with extensive metabolism and plasma protein binding further limiting infant exposure 1, 2
• The European Respiratory Society states that excretion into breast milk is very low 3
• Expert consensus indicates that the benefits of breastfeeding overwhelm the risk of exposure to montelukast 1
• The FDA label confirms that montelukast is excreted in rat milk, though human data are limited, and recommends caution when given to nursing mothers 4

Practical Recommendations for Montelukast

• Continue breastfeeding while taking montelukast without interruption or milk discarding 1
• To further minimize infant exposure, consider timing breastfeeding immediately before taking the medication 2
• No dose adjustment or special monitoring is required for the breastfed infant 1

Levocetirizine Safety Profile

Levocetirizine is acceptable during breastfeeding, though cetirizine and loratadine are preferred alternatives due to more extensive safety data. 3, 1

• The FDA label for levocetirizine states it is "not recommended" during breastfeeding, which represents a conservative position not fully supported by clinical guideline societies 5
• The European Respiratory Society classifies antihistamines as "compatible" or "probably safe" during breastfeeding, with loratadine and cetirizine preferred due to more accumulated experience 3
• One high-quality 2024 study supports levocetirizine use, though the evidence base is less robust than for montelukast 1
• Antihistamines may theoretically reduce milk production, though this is not well-established 3

Practical Recommendations for Levocetirizine

• If already taking levocetirizine with good control, continuing during breastfeeding is acceptable 1
• For new prescriptions, consider switching to cetirizine or loratadine, which have more extensive breastfeeding safety data 3, 1
• Monitor for any reduction in milk supply, though this is uncommon 3

Evidence Quality Comparison

The evidence supporting montelukast is stronger than for levocetirizine:

• Montelukast: Multiple international guideline societies (European Respiratory Society, American Academy of Pediatrics) with consistent recommendations, plus detailed pharmacokinetic data 3, 1, 2
• Levocetirizine: Primarily one high-quality 2024 study, with guideline societies preferring older antihistamines with more data 3, 1

Common Pitfalls to Avoid

• Do not assume all antihistamines have equivalent safety profiles during lactation - cetirizine and loratadine have more data than levocetirizine 2
• Do not discontinue breastfeeding unnecessarily - the relative infant dose for montelukast is well below the 10% threshold considered safe 3
• Do not rely solely on FDA labeling - the conservative FDA position on levocetirizine conflicts with clinical guideline recommendations that support antihistamine use during lactation 3, 5