Drugs Home > Phenergan and Pregnancy

The full risks of using Phenergan (promethazine) during pregnancy are unknown at this time. Based on limited information gathered from reports of pregnant women who have used this medication, however, there is no strong evidence to suggest that it causes birth defects. If you become pregnant while taking the drug, your healthcare provider will weigh the benefits and potential risks before making a recommendation.

Is Phenergan Safe During Pregnancy?

Phenergan® (promethazine hydrochloride) is a prescription medication approved for many different uses, including the treatment of nausea and vomiting.
At this time, it is unclear if Phenergan is safe for use during pregnancy, although there are clearly situations in which the benefits outweigh the possible risks. In particular, the drug is often used to help treat severe morning sickness (known medically as hyperemesis gravidarum).
It should be noted that this article applies only to Phenergan products that contain only promethazine as the active ingredient. Some cough syrups (such as Phenergan with Codeine) contain other active ingredients as well.

Phenergan and Pregnancy Category C

The U.S. Food and Drug Administration (FDA) uses a category system to classify the possible risks to a fetus when a specific medicine is taken during pregnancy. Pregnancy Category C is given to medicines that have not been studied in pregnant humans but that do appear to cause harm to the fetus in animal studies.
Medicines that have not been studied in any pregnant women or animals are automatically given a pregnancy Category C rating.
When given to pregnant rats at doses equivalent to 4.2 times the maximum recommended human dose, Phenergan did not cause any problems. However, when a very high dose was given to pregnant rats (equivalent to 8.4 times the maximum recommended human dose), the medicine caused fetal mortality.
Based on limited information gathered from reports of Phenergan use in pregnant women, there is no strong evidence to suggest that the drug causes birth defects. Although approved for use during labor, there is some evidence that it might increase the risk of breathing problems in newborns (although not all studies indicate that this is really a problem).
Taking Phenergan during the last two week of pregnancy also seems to decrease the ability of blood platelets to stick together in both the mother and the newborn. This could potentially cause problems with excessive bleeding.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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