What is the recommended antihistamine (CTM (Cetirizine) or Loratadine) for use during pregnancy?

Recommended Antihistamine for Pregnancy

Loratadine or cetirizine are the preferred antihistamines during pregnancy, as they are FDA Pregnancy Category B drugs with the most extensive safety data among second-generation antihistamines, though chlorphenamine (CTM) remains a reasonable alternative based on its long safety record. 1

First-Line Recommendations

Second-Generation Antihistamines (Preferred)

• Loratadine and cetirizine should be the first choice when antihistamine therapy is necessary during pregnancy, including the first trimester 1, 2
• Both are classified as FDA Pregnancy Category B, meaning no evidence of fetal harm exists, though well-controlled human studies are limited 1
• These agents have accumulated the most safety data during pregnancy among second-generation antihistamines, with large birth registries, case-control studies, and cohort studies confirming safety 1, 3, 4
• A prospective controlled study of 210 pregnancies exposed to loratadine (77.9% in first trimester) showed no increased risk of major congenital anomalies compared to controls (2.3% vs 3.0%, p=0.553) 5
• Second-generation antihistamines offer the advantage of less sedation compared to first-generation agents 1, 6

First-Generation Antihistamine Alternative

• Chlorphenamine (CTM) is often chosen by UK clinicians when antihistamine therapy is necessary because of its long safety record 1, 2, 3
• First-generation antihistamines have not been shown to be teratogenic in humans 1
• However, their sedative effects and impaired performance characteristics make them less desirable than second-generation options 1
• Chlorphenamine should be used at the lowest effective dose (4-12 mg) for the shortest possible time 3

Critical Timing Considerations

First Trimester (Highest Risk Period)

• The first trimester is when organogenesis occurs, making it the most critical time for concern about medication-induced congenital malformations 1, 2
• It is best to avoid all antihistamines during the first trimester if possible, though none has been proven teratogenic in humans 1
• When treatment is necessary, loratadine and cetirizine remain preferred due to their Category B classification and extensive safety data 1, 2

Later Trimesters

• Antihistamine use during the last 2 weeks of pregnancy has been associated with retrolental fibroplasia in premature infants in one study, though these findings have not been corroborated 1
• Loratadine and cetirizine remain the preferred agents throughout pregnancy 1

Specific Agents to Avoid

• Hydroxyzine is specifically contraindicated during early pregnancy based on UK manufacturer guidelines and animal data showing potential risks 1, 2
• Levocetirizine should be avoided during the first trimester due to limited safety data 2
• Intranasal antihistamines should be avoided during pregnancy 4

Additional Safety Considerations

Breastfeeding

• Antihistamines may theoretically reduce milk production 1
• Cetirizine FDA labeling states it is "not recommended" during breastfeeding 7
• Antibody excretion into breast milk is likely minimal with most antihistamines 1

Non-Pharmacological Options First

• Consider conservative measures before medication: saline nasal lavage, positioning, exercise, and nasal valve dilators are safe alternatives 8
• Intranasal corticosteroids (particularly budesonide) and sodium cromoglycate may be considered as first-line therapy with superior safety profiles 8, 6

Common Pitfalls to Avoid

• Do not assume all antihistamines have equivalent safety profiles - they do not, and specific agents like hydroxyzine must be avoided 2
• Avoid oral decongestants during the first trimester due to associations with cardiac, ear, gut, and limb abnormalities 1, 2, 8
• Do not combine decongestants with acetaminophen or salicylates, as this may increase malformation risk 2
• Do not use diphenhydramine as first choice despite frequent use, as it has been associated with cleft palate development 1

Clinical Algorithm

1. Attempt non-pharmacological measures first (saline lavage, positioning) 8
2. If medication required, choose loratadine or cetirizine as first-line agents throughout pregnancy 1, 2
3. Chlorphenamine is acceptable alternative if second-generation agents unavailable or ineffective 1, 3
4. Use lowest effective dose for shortest duration to minimize fetal exposure 3
5. Avoid hydroxyzine, levocetirizine, and oral decongestants especially in first trimester 1, 2, 8