Antihistamine Use During Pregnancy

First-Line Recommendations

Loratadine and cetirizine should be the first choice when antihistamine therapy is necessary during pregnancy, including the first trimester, as recommended by the European Respiratory Society and the Journal of Allergy and Clinical Immunology 1, 2, 3
Both loratadine and cetirizine are classified as FDA Pregnancy Category B, meaning no evidence of fetal harm exists, though well-controlled human studies are limited, according to the British Journal of Dermatology and the Journal of Allergy and Clinical Immunology 4, 2

The first trimester is when organogenesis occurs, making it the most critical time for concern about medication-induced congenital malformations, as stated by the Journal of Allergy and Clinical Immunology and the European Respiratory Journal 2, 1
It is best to avoid all antihistamines during the first trimester if possible, though none has been proven teratogenic in humans, according to the British Journal of Dermatology 4

Hydroxyzine is specifically contraindicated during early pregnancy based on UK manufacturer guidelines and animal data showing potential risks, as reported by the British Journal of Dermatology and Praxis Medical Insights 4, 3
Levocetirizine should be avoided during the first trimester due to limited safety data, according to Praxis Medical Insights 3

Antihistamines may theoretically reduce milk production, as stated by the European Respiratory Journal 1
Antibody excretion into breast milk is likely minimal with most antihistamines, according to the European Respiratory Journal 1

Do not assume all antihistamines have equivalent safety profiles - they do not, and specific agents like hydroxyzine must be avoided, as recommended by Praxis Medical Insights 3
Avoid oral decongestants during the first trimester due to associations with cardiac, ear, gut, and limb abnormalities, as reported by the Journal of Allergy and Clinical Immunology and Praxis Medical Insights 2, 3

The American Academy of Allergy, Asthma, and Immunology recommends loratadine and cetirizine as first-line antihistamines during pregnancy, with no clinically meaningful difference in safety between them 5
The European Respiratory Society suggests choosing between loratadine and cetirizine based on prior response, side effect profile, and cost, with the option to continue the same medication if the patient has already been using it successfully before pregnancy 6

Cetirizine may cause mild drowsiness in 13.7% of patients, while loratadine is generally less sedating 7

The European Respiratory Society recommends combining loratadine or cetirizine with intranasal corticosteroids, such as budesonide, for moderate-severe symptoms 6