Chlorphenamine (chlorpheniramine) is a first-generation sedating antihistamine used for the symptomatic relief of allergic disorders.
The available data do not show that chlorphenamine use in pregnancy is associated with an increase in the overall rate of congenital malformation. Associations between first trimester in utero chlorphenamine exposure and various specific malformations have been described in a small number of case-control studies. These have included eye and ear anomalies, neural tube defects, specific cardiac defects and facial clefting. However, these findings are generally considered limited by the study methodologies which may have introduced risks of chance findings. Further prospective studies investigating these associations are therefore required.
The limited published data do not suggest an increased risk of spontaneous abortion after in utero chlorphenamine exposure. No studies have investigated the incidence of intrauterine death, low infant birth weight, preterm delivery or neonatal complications with use of chlorphenamine during pregnancy. Studies in which antihistamines have been analysed as a therapeutic class have not shown any increased risk of these outcomes. There are no data regarding infant neurodevelopment after in utero exposure to chlorphenamine or other antihistamines.
Where use of chlorphenamine in pregnancy is being considered, the available pregnancy safety data and its limitations should be discussed with the patient. Exposure to chlorphenamine at any stage of pregnancy would not usually be regarded as medical grounds for termination of pregnancy or any additional fetal monitoring. However, other risk factors may be present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.
This is a summary of the full UKTIS monograph for health care professionals and should not be used in isolation. The full UKTIS monograph and access to any hyperlinked related documents is available to NHS health care professionals who are logged in.
If you have a patient with exposure to a drug or chemical and require assistance in making a patient-specific risk assessment, please telephone UKTIS on 0344 892 0909 to discuss the case with a teratology specialist.
If you would like to report a pregnancy to UKTIS please click here to download our pregnancy reporting form. Please encourage all women to complete an online reporting form.