Is fexofenadine (Allegra) safe to use during pregnancy?

Fexofenadine Safety During Pregnancy

Fexofenadine (Allegra) is generally considered safe to use during pregnancy, with recent evidence showing no increased risk of adverse fetal outcomes compared to other commonly used antihistamines. 1

Evidence on Fexofenadine in Pregnancy

Safety Profile

• The FDA pregnancy category for fexofenadine is C, indicating that animal studies have not shown evidence of teratogenicity at doses up to 30 times the human exposure, but there are limited controlled studies in pregnant women 2
• A 2020 nationwide registry-based cohort study of over 1.2 million pregnancies found that fexofenadine use during pregnancy was not associated with increased risk of:
  • Major birth defects
  • Spontaneous abortion
  • Preterm birth
  • Small for gestational age
  • Stillbirth 1

Transplacental Transfer

• Fexofenadine has low transplacental transfer (approximately 16%), which may contribute to its favorable safety profile 3
• This limited placental transfer helps minimize fetal exposure to the medication

Recommendations for Antihistamine Use in Pregnancy

First-Line Options

• While fexofenadine appears safe, current guidelines from the American Academy of Allergy, Asthma, and Immunology recommend the following as first-line antihistamines during pregnancy due to their longer history of documented safety 4:
  • Loratadine
  • Cetirizine
  • Chlorpheniramine (first-generation)

Timing Considerations

• If possible, antihistamines should be avoided during the first trimester when the risk of congenital malformations is greatest, unless the benefits outweigh potential risks 4
• For women who require antihistamine therapy throughout pregnancy, including the first trimester, those with established safety data are preferred

Clinical Approach to Antihistamine Use in Pregnancy

Algorithm for Antihistamine Selection in Pregnancy:

1. First trimester:

   • Consider non-pharmacological approaches first (allergen avoidance, saline nasal irrigation)
   • If medication needed: use loratadine or cetirizine as first choice
   • Fexofenadine can be considered if patient has previously responded well to it

2. Second and third trimesters:

   • Loratadine or cetirizine remain first choice
   • Fexofenadine is an acceptable alternative with good safety data 1

3. For women already on fexofenadine before pregnancy:

   • Can continue fexofenadine if well-controlled on this medication
   • No need to switch to another antihistamine based on current evidence 1

Important Precautions

• Avoid combining antihistamines with oral decongestants, especially during the first trimester 4
• Take fexofenadine with water rather than fruit juices, as juices can reduce its bioavailability by up to 36% 2
• Use the lowest effective dose to manage symptoms

Conclusion

Fexofenadine appears to be a safe option for treating allergic conditions during pregnancy, with no evidence of increased risk of adverse fetal outcomes in recent large studies. While loratadine and cetirizine have longer established safety records and remain first-line options, fexofenadine represents a reasonable alternative, particularly for women who have previously responded well to this medication or cannot tolerate other antihistamines.