Is bilastine (histamine H1 receptor antagonist) safe to use during early pregnancy?

Safety of Bilastine in Early Pregnancy

Bilastine should not be used during early pregnancy due to insufficient safety data in pregnant women, despite its favorable safety profile in non-pregnant populations. 1, 2

Current Evidence on Antihistamines in Pregnancy

• In general, H1-antihistamines have not been linked to increased risk of congenital anomalies, though specific safety data on bilastine in pregnancy is lacking 3
• First-generation antihistamines are considered safer to use during pregnancy due to more extensive safety data, while second-generation antihistamines (like bilastine) have relatively fewer data 4
• When antihistamine therapy is necessary during pregnancy, guidelines recommend using medications with established safety profiles 5

Recommended Antihistamine Options During Pregnancy

• Loratadine or cetirizine should be preferred during pregnancy as they have been most extensively studied 3
• Famotidine (H2-blocker) is classified as FDA Pregnancy Category B and can be considered a safer option when antihistamine therapy is necessary 5
• First-generation antihistamines should be avoided due to their sedative and anticholinergic properties, despite their longer safety record 3

Important Considerations for Medication Use in Pregnancy

• The benefit of any drug used during pregnancy should outweigh the risk to the fetus 6
• For allergic rhinitis during pregnancy, saline nasal lavage and topical corticosteroid nasal sprays are considered safe and effective first-line treatments 3
• Oral decongestants should be avoided during pregnancy, especially in the first trimester, due to potential associations with congenital malformations 3

Pharmacological Properties of Bilastine

• Bilastine is a highly selective H1 receptor antagonist with no sedative effects, no cardiotoxicity, and no hepatic metabolism 1
• Unlike other antihistamines, bilastine is not metabolized and is excreted largely unchanged, suggesting potentially lower risk of drug interactions 2
• However, these favorable pharmacological properties do not overcome the lack of specific pregnancy safety data 1, 2

Clinical Decision-Making Algorithm

1. For pregnant patients requiring antihistamine therapy:
   • First consider non-pharmacological approaches (allergen avoidance, saline nasal rinses) 3
   • If medication is necessary, select antihistamines with established pregnancy safety data (loratadine or cetirizine) 3
   • Avoid bilastine due to insufficient pregnancy safety data 1, 2
   • Monitor for symptom control and adjust therapy as needed 3

Common Pitfalls to Avoid

• Do not assume that newer antihistamines like bilastine are automatically safe in pregnancy simply because they have favorable safety profiles in non-pregnant populations 1, 2
• Do not use oral decongestants during pregnancy, especially in the first trimester 3
• Do not initiate allergen immunotherapy during pregnancy, though existing therapy may be continued at the same dose if beneficial 3
• Do not assume that all antihistamines carry the same risk profile during pregnancy 3, 4