Is bilastine (antihistamine) safe to use during pregnancy?

Safety of Bilastine During Pregnancy

Bilastine should be avoided during pregnancy, especially in the first trimester, as there is insufficient safety data for this specific antihistamine in pregnant women. 1

General Antihistamine Use in Pregnancy

The British Journal of Dermatology guidelines clearly state that it is best to avoid all antihistamines during pregnancy, particularly during the first trimester, although none has been shown to be teratogenic in humans 1. When antihistamine therapy is necessary during pregnancy, the following approach is recommended:

Preferred Antihistamines If Treatment Is Necessary

• First choice: Chlorphenamine (chlorpheniramine) is often chosen by clinicians due to its long safety record 1
• Second choice: Loratadine and cetirizine are classified as FDA Pregnancy Category B drugs, implying no evidence of harm to the fetus, although well-controlled human studies are limited 1

Risk Assessment for Antihistamines

• First-generation antihistamines (like chlorphenamine) have more extensive safety data during pregnancy 2, 3
• Second-generation antihistamines have fewer data but published studies are generally reassuring 3
• For bilastine specifically, there is a lack of sufficient human pregnancy data to recommend its use

Important Considerations When Antihistamine Therapy Is Required

Timing Considerations

• Greatest caution should be exercised during the first trimester when organogenesis occurs 1
• If treatment is necessary, use the lowest effective dose for the shortest duration

Medication Selection Algorithm

1. First attempt non-pharmacological approaches (allergen avoidance)
2. If medication is necessary, use chlorphenamine as first-line therapy due to its established safety record
3. If first-generation antihistamines are not tolerated, consider loratadine or cetirizine (Category B drugs)
4. Avoid newer antihistamines like bilastine that lack sufficient pregnancy safety data

Special Warnings

• First-generation antihistamines should be used with caution due to their sedating properties 1
• Oral decongestants should be avoided during pregnancy, especially in the first trimester, due to potential associations with congenital malformations 1
• For allergic rhinitis during pregnancy, intranasal cromolyn sodium and intranasal corticosteroids (particularly budesonide) may be safer first-line options 4, 2

Conclusion

When managing allergic conditions during pregnancy, the safety of the mother and fetus is paramount. While no antihistamine has been definitively proven teratogenic in humans, the lack of specific safety data for bilastine means it should be avoided in favor of antihistamines with more established safety profiles such as chlorphenamine, loratadine, or cetirizine when treatment is necessary.