What antihistamines (anti histaminics) are safe to use during pregnancy?

Safe Antihistamines in Pregnancy

Cetirizine and loratadine are the first-line antihistamines during pregnancy, including the first trimester, with the most extensive safety data demonstrating no increased risk of congenital malformations. 1, 2

First-Line Recommendations

• Cetirizine and loratadine should be your go-to antihistamines when treatment is necessary during pregnancy. Both are FDA Pregnancy Category B, meaning animal studies show no fetal harm and large human observational studies have confirmed safety across all trimesters. 3, 1, 2

• These second-generation agents now have accumulated safety data comparable to older first-generation antihistamines (over 200,000 first-trimester exposures studied), but without the problematic sedation that impairs maternal performance and concentration. 3, 2, 4

• Loratadine has been studied in 2,147 pregnant women with no increased teratogenic risk, making it one of the most extensively evaluated second-generation antihistamines. 5

Critical Timing Considerations

• The first trimester is when organogenesis occurs, making it the most critical window for medication-induced congenital malformations—this is when you need to be most cautious, though cetirizine and loratadine remain safe options even during this period. 3, 1, 2

• While guidelines traditionally state "it is best to avoid all antihistamines during the first trimester," this recommendation is increasingly outdated given the robust safety data now available for cetirizine and loratadine. 3

Specific Agents to Avoid

• Hydroxyzine is specifically contraindicated during early pregnancy based on UK manufacturer guidelines and animal teratogenicity data—this is the only antihistamine with a specific contraindication. 3, 1, 2

• Levocetirizine, desloratadine, azelastine, and fexofenadine have limited human pregnancy data and should be avoided when better-studied alternatives (cetirizine, loratadine) are available. 3, 2

• Diphenhydramine carries some concern over a case-control study suggesting association with cleft palate, though recent studies have not confirmed increased risk—still, better alternatives exist. 3

Alternative First-Generation Options

• Chlorphenamine (chlorpheniramine) is often chosen by UK clinicians when antihistamine therapy is necessary because of its long safety record spanning decades, though sedation is a significant drawback. 3

• First-generation antihistamines have been studied in over 200,000 first-trimester exposures without showing increased teratogenic risk, but their sedating effects make them less desirable than cetirizine or loratadine. 3, 5, 6

Adjunctive and Alternative Therapies

• Intranasal corticosteroids (particularly budesonide) are actually more effective than antihistamines for rhinitis and have excellent safety profiles with minimal systemic absorption—consider these as first-line therapy before antihistamines. 2, 4, 5

• Sodium cromolyn nasal spray (Pregnancy Category B) is safe but requires four-times-daily dosing, which limits patient acceptance despite good safety data. 3, 2

• Montelukast has reassuring animal data and Pregnancy Category B classification, but should be reserved for patients with documented excellent pre-pregnancy responses. 3, 2

Medications to Definitively Avoid

• Oral decongestants (pseudoephedrine, phenylephrine) must be avoided during the first trimester due to conflicting reports associating them with gastroschisis, small intestinal atresia, and other congenital malformations, especially when combined with acetaminophen or NSAIDs. 3, 2

• Topical intranasal decongestants have not been adequately studied in pregnancy and should be used only for short-term relief when no safer alternatives exist. 3

Common Pitfalls to Avoid

• Do not assume all antihistamines have equivalent safety profiles—the quality of human pregnancy data varies dramatically between agents, and hydroxyzine specifically must be avoided. 1, 2

• Do not reflexively choose first-generation antihistamines based solely on "longer history of use"—cetirizine and loratadine now have comparable safety data spanning hundreds of thousands of exposures without the sedation risks. 3, 2

• Do not overlook intranasal corticosteroids, which are often more effective than oral antihistamines for rhinitis symptoms and have minimal systemic absorption. 2, 5

• Do not combine oral decongestants with acetaminophen or salicylates during pregnancy, as this combination increases malformation risk beyond decongestants alone. 3, 2

Lactation Considerations

• Antihistamines may theoretically reduce milk production, though antibody excretion into breast milk is likely minimal with most agents. 1

• Caution is still recommended during lactation, particularly in the early postpartum period. 3