Is chlorpheniramine safe during pregnancy?

What does the evidence say about chlorpheniramine during pregnancy?

1. Most studies find no overall increased chance of birth defects with chlorpheniramine use in pregnancy, though two studies noted a small increase with no specific pattern of defect emerging. 1
2. Studies of antihistamines including chlorpheniramine have not suggested an increased chance of miscarriage. 1
3. Chlorpheniramine is not expected to raise the chance of pregnancy-related problems such as delivery before week 37 or low birth weight. 1
4. Chlorpheniramine and diphenhydramine are described as safe during the first trimester in a World Allergy Organization review, which names loratadine and cetirizine as the second-generation options of choice. 2
5. The over-the-counter label doses chlorpheniramine at 4 mg every four to six hours with a ceiling of six tablets in 24 hours for adults, and states plainly that drowsiness may occur. 3

Is chlorpheniramine safe in each trimester?

• First trimester. Chlorpheniramine is the older antihistamine most often named as an acceptable early-pregnancy choice, and most studies have found no overall increase in birth defects. Two studies did report a small increase, though without any consistent pattern of defect behind it. Starting at the lowest dose that actually settles your symptoms is a sensible opening position to bring to your provider.
• Second trimester. Congestion and allergy symptoms tend to peak through the middle months as nasal tissue swells. Chlorpheniramine has not been linked to preterm delivery or low birth weight. Because it is dosed every four to six hours rather than once daily, some people take it only in the evening so the sleepiness lands when it is least disruptive.
• Third trimester. Sedation is the practical issue this late, when fatigue is already running high. The over-the-counter label caps adults at six 4 mg tablets in 24 hours and notes that alcohol, sedatives, and tranquilizers stack on top of the drowsiness. Mention ongoing use at a late visit so it becomes part of your delivery and feeding plan.