Fexofenadine (Allegra) Use During Pregnancy
Fexofenadine can be used during pregnancy when needed to control allergic symptoms, as it has not been associated with increased risk of birth defects or adverse fetal outcomes, though cetirizine or loratadine are preferred first-line second-generation antihistamines due to more extensive safety data. 1, 2
Safety Profile and Evidence Quality
Second-generation antihistamines as a class, including fexofenadine, have been confirmed safe during first trimester use through large birth registries, case-control studies, and cohort studies, with no significant increase in congenital malformations. 1
A 2020 Danish nationwide registry study of 2,962 pregnancies with fexofenadine exposure found no increased risk of major birth defects (4.0% vs 3.8% with cetirizine; OR 1.06,95% CI 0.81-1.37) or spontaneous abortion (8.4% vs 9.0% with cetirizine; HR 0.93,95% CI 0.82-1.07). 2
The same study found no increased risk of preterm birth, small for gestational age, or stillbirth with fexofenadine use. 2
Important Caveats and Limitations
The main limitation is that no large-scale epidemiologic studies in human pregnancy were published at the time of the 2008 guideline development, though animal studies showed no teratogenicity. 1
The FDA classifies fexofenadine as Pregnancy Category C, stating it "should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus." 3
Animal studies at high doses (up to 300 mg/kg in rats and rabbits) showed no teratogenic effects, with fexofenadine exposures approximately 3-30 times the maximum human dose. 3
Clinical Recommendations
Preferred antihistamine choices during pregnancy based on more extensive safety data: 1, 4
- Cetirizine - second-generation antihistamine of choice
- Loratadine - second-generation antihistamine of choice
- Chlorpheniramine - first-generation option (though causes sedation)
If fexofenadine is selected: 3
- Use the lowest effective dose
- Take with water (not fruit juices, which reduce bioavailability by 36%)
- Avoid first trimester use when possible, as this is the critical period for organogenesis 1
Alternative Treatment Options
Intranasal sodium cromolyn is safe during pregnancy (Pregnancy Category B) and may be considered as first-line therapy, though requires four-times-daily dosing. 1
Intranasal corticosteroids (particularly budesonide) are safe and effective options during pregnancy. 4
Montelukast has reassuring safety data (Pregnancy Category B) and can be used when there has been favorable prepregnancy response. 1
Key Clinical Pitfalls to Avoid
Do not combine antihistamines with oral decongestants during first trimester - oral decongestants (pseudoephedrine, phenylephrine) should be avoided in the first trimester due to associations with gastroschisis and small intestinal atresia. 1
Avoid diphenhydramine as first choice - despite frequent use, there remains concern over case-control data suggesting association with cleft palate. 1
Avoid hydroxyzine during first trimester - should be used cautiously based on animal data. 1