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Date of issue: December 2019, Version: 3

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A corresponding patient information leaflet on USE OF PROMETHAZINE IN PREGNANCY is available.

Promethazine is a first generation (sedating) phenothiazine antihistamine used in the treatment of nausea and vomiting, allergy such as hay fever and urticaria, emergency treatment of anaphylactic reactions, and for sedation.

Studies (including two small studies on fetal exposure to promethazine through maternal overdose) do not suggest an association between in utero promethazine exposure and increased risks of congenital malformation, preterm delivery, low birth weight or adverse neurodevelopmental outcome. Risk of miscarriage has not been studied. In the UK, manufacturers of promethazine state that, due to the risk of neonatal irritability and excitement, use should be avoided in the last two weeks of pregnancy.

Exposure to promethazine at any stage in pregnancy would not usually be regarded as medical grounds for termination of pregnancy or any additional fetal monitoring. However, neonatal monitoring may be necessary where antenatal exposure has occurred close to delivery, and 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.

Disclaimer: Every effort has been made to ensure that this monograph was accurate and up-to-date at the time of writing, however it cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes of the measures recommended. The final decision regarding which treatment is used for an individual patient remains the clinical responsibility of the prescriber. This material may be freely reproduced for education and not for profit purposes within the UK National Health Service, however no linking to this website or reproduction by or for commercial organisations is permitted without the express written permission of this service. This document is regularly reviewed and updated. Only use UKTIS monographs downloaded directly from to ensure you are using the most up-to-date version.