Is promethazine safe during pregnancy?

What does the evidence say about promethazine during pregnancy?

1. Taking promethazine during pregnancy is not expected to increase the chance of birth defects, and one small study found no rise in miscarriage. 1
2. Some reports suggest that promethazine late in pregnancy might increase the chance of slowed breathing, known as respiratory depression, in newborns. 1
3. Promethazine is an H1 receptor blocking agent whose sedative and antiemetic effects appear within about 20 minutes of an oral dose and generally last four to six hours, occasionally as long as twelve. 2
4. Nausea and vomiting of pregnancy is often left undermanaged because people worry about medication safety, and ACOG notes that acting in the early stages may head off more serious complications including hospitalization. 3
5. In an emergency department cohort of 439 women with nausea and vomiting of pregnancy, promethazine was among the first-line antiemetics used, with time from dose to discharge comparable to ondansetron. 4

Is promethazine safe in each trimester?

• First trimester. Promethazine is usually a later step, after vitamin B6 with or without doxylamine. Taking it during pregnancy is not expected to increase the chance of birth defects, and one small study found no rise in miscarriage. The call belongs to the clinician who knows how much weight and fluid you are losing.
• Second trimester. Sedation is the practical issue here. Effects generally show up within about 20 minutes of an oral dose and last four to six hours, so sort out driving, work, and childcare before the first dose rather than discovering it the hard way.
• Third trimester. Late pregnancy carries a specific caution: some reports suggest promethazine near delivery might raise the chance of slowed breathing in newborns. Make sure whoever is on your delivery team knows you are taking it as your due date gets close.