Are levocetrizine and montelukast (antihistamine and leukotriene receptor antagonist) safe to use during pregnancy?

Safety of Levocetirizine and Montelukast During Pregnancy

Montelukast can be safely used during pregnancy, particularly for recalcitrant asthma in patients with prior favorable response, while levocetirizine should be avoided during the first trimester due to limited safety data. 1, 2

Montelukast Safety Profile

• Montelukast is classified as FDA Pregnancy Category B, indicating no evidence of teratogenicity in animal studies 3
• No teratogenic effects were observed in rats at doses up to 400 mg/kg/day and in rabbits at doses up to 300 mg/kg/day 3
• The American Congress of Obstetricians and Gynecologists and the American College of Allergy recommend montelukast for recalcitrant asthma during pregnancy, particularly in patients who have shown favorable response prior to pregnancy 4, 1
• A prospective comparative study of 180 montelukast-exposed pregnancies did not show an increased rate of major malformations above the baseline risk 5
• Montelukast does not appear to be a major human teratogen based on available evidence, though sample sizes in studies remain limited 6

Levocetirizine Safety Profile

• Limited specific safety data exist for levocetirizine use during pregnancy, particularly in the first trimester 2
• The American Academy of Allergy, Asthma, and Immunology recommends avoiding levocetirizine during the first trimester if possible 2
• If antihistamine treatment is necessary during pregnancy, chlorphenamine, cetirizine, or loratadine are preferred due to their better documented safety profiles 2

Breastfeeding Considerations

• About 1% of montelukast passes into breast milk, but extensive metabolism and plasma protein binding limit infant exposure 4, 1
• For nursing mothers using montelukast, the benefits of breastfeeding generally outweigh the risk of exposure 4
• Consider breastfeeding prior to medication intake to further limit exposure 4
• Limited data exist on levocetirizine excretion in breast milk 4

Treatment Algorithm

For asthma management during pregnancy:

• First-line: Consider non-pharmacological approaches if appropriate 2
• For asthma requiring medication: Montelukast can be continued or initiated, especially if there was a favorable response before pregnancy 4, 1
• Monitor asthma control regularly throughout pregnancy 1

For allergic rhinitis during pregnancy:

• First-line: Consider intranasal corticosteroids or sodium cromolyn 4
• If oral antihistamines are needed: Choose chlorphenamine, cetirizine, or loratadine over levocetirizine 2
• Avoid oral decongestants, especially during the first trimester 4

Common Pitfalls and Caveats

• Assuming all antihistamines have equivalent safety profiles during pregnancy is incorrect 2
• Poorly controlled asthma poses greater risks to maternal and fetal health than appropriate medication use 1
• Oral decongestants should be avoided during the first trimester due to potential risks of congenital malformations 4
• First-generation antihistamines should be avoided given their sedative and anticholinergic properties 4
• The manufacturer of montelukast maintains a registry for patients exposed to the medication during pregnancy 3
• Healthcare providers should report prenatal exposure to montelukast by calling the Pregnancy Registry 3