In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. This sheet talks about whether exposure to promethazine may increase the risk for birth defects over that background risk. This information should not take the place of medical care and advice from your healthcare professional.

What is promethazine?

Promethazine is a medication that is used for the treatment of nausea and vomiting, motion sickness, and allergies. Promethazine has been sold under the brand name Phenergan®.

I just found out I am pregnant. Should I stop taking promethazine?

Talk with your healthcare provider before making any changes to your medications. If you are experiencing nausea and vomiting that is affecting your daily life, please contact your healthcare provider. There are many medications used in pregnancy to treat nausea and vomiting that are well studied. For more information about nausea and vomiting during pregnancy, please see the MotherToBaby fact sheet Nausea and Vomiting in Pregnancy at http://mothertobaby.org/fact-sheets/nausea-vomiting-pregnancy-nvp/pdf/.

Can use of promethazine during pregnancy cause birth defects?

This would be unlikely. The majority of studies do not suggest that promethazine would increase the chance for birth defects when used during the 1st trimester.

Can use of promethazine cause other pregnancy complications?

The use of promethazine late in pregnancy might increase the chance of respiratory depression (slow breathing rate) in newborn babies.

Can I breastfeed while using promethazine?

There is no data on the use of promethazine while breastfeeding. Because promethazine can cause sleepiness in adults, it may do the same for a nursing baby. For this reason it may not be a preferred antihistamine for long-term use during breastfeeding. If you use promethazine routinely while breastfeeding, monitor your baby for sedation and lack of energy and report any of these symptoms to your health care provider. It is possible, but not proven, that promethazine could lower the amount of milk a woman makes. If you are having trouble producing milk, consider meeting with a lactation specialist. Be sure to talk to your health care providers about all of your breastfeeding questions.

What if the father of the baby takes promethazine?

There is no evidence suggesting that a man’s promethazine use would cause problems conceiving a baby or problems during pregnancy. In general, exposures that fathers have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures and Pregnancy at http://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/pdf/.

Selected References:

  • Anderka M, et al. 2012. Medications used to treat nausea and vomiting of pregnancy and the risk of selected birth defects. Birth Defects Res A Clin Mol Teratol. Jan;94(1):22-30.
  • Bartfai Z, et al. 2008. A population-based case-control teratologic study of promethazine use during pregnancy. Reprod Toxicol. 25:276-285.
  • Corby DG, Shulman I. 1971. The effects of antenatal drug administration on aggregation of platelets of newborn infants. J Pediatr. 79:307-13.
  • Gilboa SM, et al. 2009. National Birth Defects Prevention Study: Use of antihistamine medications during early pregnancy and isolated major malformations. Birth Defects Res A Clin Mol Teratol. 85(2):137-150.
  • Hall PF. 1987. Use of promethazine (Phenergan) in labour (letter). Can Med Assoc J; 136:690-1.
  • Heinonen OP et al. 1997. Birth Defects and Drugs in Pregnancy, Littleton, Publishing Sciences Group, pp 323-4, 437.
  • Hildebrandt HM. 1999. Maternal perception of lactogenesis time: a clinical report. J Hum Lact.15:317-23.
  • Larrimer MB, et al. 2014. Antiemetic medications in pregnancy: a prospective investigation of obstetric and neurobehavioral outcomes. Am J Obstet Gynecol 270: e1-e7.
  • Messinis IE, et al. 1985. Histamine H1 receptor participation in the control of prolactin secretion in postpartum. J Endocrinol Invest.8:143-6.
  • Petik D, et al. 2008. A study of the potential teratogenic effect of large doses of promethazine used for a suicide attempt by 32 pregnant women. Toxicol Ind Health; 24(1-2):87-96.
  • Petik D, et al. 2012. A study of the risk of mental retardation among children of pregnant women who have attempted suicide by means of a drug overdose. J Inj Violence Res. Jan;4(1):10-19.
  • Starke PR, et al. 2005. Boxed warning added to promethazine labeling for pediatric use. NEJM 2005;352:2653.
  • Whaun JM et al: Effect of prenatal drug administration on maternal and neonatal platelet aggregation and PF4 release. Haemostasis 1980; 9:226-37