First Exposure

Phenylephrine

Information last updated: June 2023 

The baseline risk of major birth defects in Canada is 3-5%. This means that 3-5 out of 100 babies born in the general population in Canada will be born with a major birth defect. There are also baseline risks for miscarriages (15-25 out of 100 pregnancies), prematurity and other outcomes. The information provided will summarize if taking this drug is likely to change these risks.

Summary: Approximately 1600 pregnancies with exposure to phenylephrine in first trimester of pregnancy were included in published studies. Based on these studies it is not expected that taking phenylephrine during pregnancy will cause more babies to be born with major birth defects than in the general population.  

Phenylephrine can constrict blood vessels (make them narrower). It is not known if the effects of this constriction could decrease the blood flow to the placenta. For this reason, use for more than a few days should be avoided. Phenylephrine can also increase blood pressure, and therefore cautious use is advised.

This information about phenylephrine is of a general nature and about medical use and does not replace the medical care and advice of your healthcare provider. For questions on dose, timing, side effects, interactions, etc., please consult your healthcare provider. Additionally, please read carefully the patient insert provided with your medication.

Although participants in the studies referenced below may have used phenylephrine in various combinations, the studies usually do not provide detailed information on drug combinations. This makes it challenging to comment on the safety of using this medication in combination with others during pregnancy or lactation.