Are montelukast (Singulair) and cetirizine (Zyrtec) safe for a lactating woman to use for allergy or asthma management?

Safety of Montelukast and Cetirizine During Breastfeeding

Both montelukast and cetirizine are safe to use during breastfeeding, with montelukast having particularly strong evidence showing only 0.68% of the maternal dose reaches the infant, and cetirizine being one of the preferred antihistamines with extensive safety data. 1, 2, 3

Montelukast Safety Profile

Montelukast excretion into breast milk is extremely low and poses minimal risk to the nursing infant. 2, 3

• Only approximately 1% of the maternal dose passes into breast milk, with peak concentrations occurring at 4 hours post-dose 2, 3
• The relative infant dose is just 0.68% of the weight-adjusted maternal dose, which is far below therapeutic ranges for infants 3
• Average milk concentrations are only 5.3 ng/mL, with maximum concentrations reaching 9.7 ng/mL 3
• Extensive metabolism and plasma protein binding further limit infant exposure beyond the already minimal milk transfer 2

Expert consensus strongly supports montelukast use during lactation, with multiple guideline societies stating that the benefits of breastfeeding overwhelm any theoretical risk of exposure. 2

Practical Recommendations for Montelukast

• Continue breastfeeding without interruption while taking montelukast 2
• If desired, consider breastfeeding immediately before taking the medication to further minimize infant exposure, though this is not necessary given the already negligible transfer 2, 4
• No monitoring of the infant is required 3

Cetirizine Safety Profile

Cetirizine is one of the preferred second-generation antihistamines for use during breastfeeding, with extensive accumulated safety data. 1, 4

• The European Respiratory Society and other guideline societies specifically recommend cetirizine (along with loratadine) as preferred antihistamines due to their established safety records 1, 4
• The 2005 NAEPP Expert Panel Report identifies cetirizine as a current second-generation antihistamine of choice for lactating women 1
• Cetirizine is classified as "compatible" with breastfeeding by major guideline societies 1

Important Caveat About Antihistamines

• Antihistamines may theoretically reduce milk production, though this is not well-established clinically 1
• Monitor for any changes in milk supply, particularly in the early postpartum period when lactation is being established 1

Comparative Evidence Quality

The evidence supporting montelukast safety during breastfeeding is stronger than for many other medications, with both high-quality research studies and multiple guideline endorsements. 2, 3

• Montelukast has direct pharmacokinetic data from a 2017 study measuring actual drug levels in breast milk 3
• Multiple international guideline societies (American Academy of Pediatrics, European Respiratory Society) have reviewed and endorsed its safety 1, 2
• Cetirizine has decades of clinical use data supporting its safety profile 1, 4

Clinical Context for Combined Use

Both medications can be used simultaneously during breastfeeding if clinically indicated for asthma and allergic rhinitis management. 1

• Montelukast is effective for both asthma control and allergic rhinitis treatment 1, 5
• Cetirizine provides additional symptomatic relief for allergic rhinitis symptoms 1, 5
• The combination of a leukotriene receptor antagonist with an antihistamine may provide superior symptom control compared to either agent alone 6