Is bilastine (antihistamine) safe to use during pregnancy?

Bilastine Safety in Pregnancy

Bilastine should be avoided during pregnancy due to insufficient safety data; instead, use loratadine or cetirizine as first-line antihistamines, which have established safety profiles and are recommended by major guidelines.

Specific Concerns with Bilastine

• Bilastine lacks specific safety data in pregnancy, making it unsuitable for use when safer alternatives with extensive human data are available 1
• No published studies have evaluated bilastine's teratogenic potential or pregnancy outcomes in humans 2
• The general principle is that medications without established pregnancy safety data should only be used if potential benefit clearly justifies potential fetal risk 3

Recommended Antihistamine Alternatives

First-Line Agents:

• Loratadine and cetirizine are the preferred antihistamines throughout pregnancy, including the first trimester, as they have been most extensively studied and show no increased risk of congenital malformations 4, 1
• Both agents are FDA Pregnancy Category B, meaning no evidence of fetal harm exists in available studies 4
• The European Respiratory Society and American Academy of Allergy, Asthma, and Immunology both recommend these as first-choice agents when antihistamine therapy is necessary 4

Choosing Between Loratadine and Cetirizine:

• Select based on prior patient response, side effect profile, and cost 4
• Cetirizine may cause mild drowsiness in 13.7% of patients, while loratadine is generally less sedating 4
• No clinically meaningful safety difference exists between them 4

Critical Timing Considerations

• The first trimester is the highest-risk period due to organogenesis, making medication selection most critical during weeks 1-12 4
• While it is best to avoid all antihistamines during the first trimester if possible, loratadine and cetirizine can be used when medically necessary 4
• None of the H1-antihistamines have been proven teratogenic in humans 1

Agents to Specifically Avoid

• Hydroxyzine is contraindicated during early pregnancy based on UK manufacturer guidelines and animal data showing potential risks 4
• Levocetirizine should be avoided during the first trimester due to limited safety data 4
• Oral decongestants must be avoided during the first trimester due to associations with cardiac, ear, gut, and limb abnormalities 4, 1

Treatment Algorithm for Allergic Conditions in Pregnancy

Step 1 - Non-Pharmacological Approaches:

• Begin with allergen avoidance strategies and saline nasal lavage 1
• Consider topical corticosteroid nasal sprays (such as budesonide) as safe and effective first-line treatments for allergic rhinitis 1

Step 2 - Add Antihistamine if Needed:

• Prescribe loratadine or cetirizine if symptoms persist despite non-pharmacological measures 4, 1
• For moderate-severe symptoms, combine loratadine or cetirizine with intranasal corticosteroids like budesonide 4

Step 3 - Monitor and Adjust:

• Monitor for symptom control and adjust therapy as needed 1
• Continue the same medication if the patient was using loratadine or cetirizine successfully before pregnancy 4

Common Pitfalls to Avoid

• Do not assume all antihistamines have equivalent safety profiles - they do not, and specific agents like hydroxyzine and bilastine must be avoided 4
• Do not rely on longer safety records of first-generation antihistamines as justification for use; their sedative and anticholinergic properties make them less desirable despite historical use 1
• Avoid prescribing antihistamines during the last 2 weeks of pregnancy when possible, as one study associated late pregnancy antihistamine use with retrolental fibroplasia in premature infants 3
• Do not discontinue effective therapy with loratadine or cetirizine upon discovering pregnancy - these medications can be safely continued 4

Additional Safety Considerations

• Antihistamines may theoretically reduce milk production, though antibody excretion into breast milk is likely minimal with most antihistamines 4
• All antihistamines are considered safe during breastfeeding, as minimal amounts are excreted in breast milk 5
• First-generation antihistamines like chlorpheniramine have demonstrated safety through long-term observational data but are less preferred due to sedative effects 3