Is montelukast (Singulair) and levocetirizine (Xyzal) safe during pregnancy?

Safety of Montelukast and Levocetirizine in Pregnancy

Montelukast can be safely used throughout pregnancy, particularly for asthma control, while levocetirizine should be avoided during the first trimester—use chlorpheniramine, cetirizine, or loratadine instead if antihistamines are needed. 1

Montelukast Safety Profile

Montelukast is considered safe for use during pregnancy and is specifically recommended by major professional societies for asthma management. 1, 2, 3

Key Safety Data:

• FDA Pregnancy Category B, meaning animal studies show no fetal risk, though controlled human studies are limited 2, 4
• The American Congress of Obstetricians and Gynecologists and the American College of Allergy support montelukast use during pregnancy when clinically indicated 1, 2
• Recent prospective cohort studies from Japan (2022) and multicenter international data (2009) show no increased risk of major congenital malformations above the 1-3% baseline rate 5, 6
• The European Respiratory Society classifies montelukast as "probably safe" with limited data suggesting no significantly increased risk of malformations 2

Clinical Recommendations for Montelukast:

• Continue or initiate montelukast for recalcitrant asthma during pregnancy, especially if there was favorable response before pregnancy 1, 2, 3
• Use at the lowest effective dose 2
• Poorly controlled asthma poses greater risks to maternal and fetal health than medication use 2, 3

Important Caveat:

• Post-marketing surveillance has reported rare cases of limb reduction defects, though a causal relationship has not been established 2, 4
• Lower birth weight (approximately 300g less) has been observed in asthma patients using montelukast, but this is likely associated with maternal asthma severity rather than the medication itself 5

Levocetirizine Safety Profile

Levocetirizine should be avoided during the first trimester due to limited safety data. 1, 3

Preferred Antihistamine Alternatives:

If antihistamine treatment is necessary during pregnancy, use these instead:

• Chlorpheniramine 1, 3
• Cetirizine 1, 3
• Loratadine 1, 3

These three antihistamines have better documented safety profiles with more accumulated safety data 3

First-Line Treatment for Allergic Rhinitis in Pregnancy:

• Intranasal corticosteroids (particularly budesonide, which is Pregnancy Category B) 2, 3
• Sodium cromolyn 1, 3

Breastfeeding Considerations

Montelukast:

• Only about 1% passes into breast milk 1, 3, 4
• Extensive metabolism and plasma protein binding limit infant exposure 1, 3
• Benefits of breastfeeding generally outweigh the risk of exposure 1, 3
• Consider breastfeeding prior to medication intake to further limit exposure 2, 3

Levocetirizine:

• Limited data exist on excretion in breast milk 1

Common Pitfalls to Avoid

• Do not assume all antihistamines have equivalent safety profiles during pregnancy—they do not 1, 3
• Avoid oral decongestants, especially during the first trimester, due to potential risks of congenital malformations 1
• Avoid first-generation antihistamines given their sedative and anticholinergic properties 1
• Do not withhold appropriate asthma medications due to pregnancy concerns—uncontrolled asthma poses greater risks than medication use 2, 3

Treatment Algorithm for Pregnancy

For Asthma:

1. First-line: Inhaled corticosteroids (particularly budesonide) with short-acting beta-agonists 2
2. Add montelukast for recalcitrant asthma when conventional inhaled medications fail to achieve adequate control 1, 2, 3
3. Continue montelukast if already on it with good response pre-pregnancy 1, 2, 3

For Allergic Rhinitis:

1. First-line: Intranasal corticosteroids or sodium cromolyn 1, 3
2. If oral antihistamines needed: Use chlorpheniramine, cetirizine, or loratadine 1, 3
3. Avoid levocetirizine in first trimester 1, 3
4. Avoid oral decongestants in first trimester 1