Zofran vs Phenergan during pregnancy

How do the options compare?

Options are stacked on five dimensions relevant to pregnancy use: mainstream OB guidance, pregnancy-specific evidence, dosing predictability, onset, and side-effect and interaction profile.

• A few studies reported a less than 1% increase in the chance of cleft palate or a heart defect with ondansetron, other studies have not confirmed those findings, and most studies of thousands of exposed pregnancies reported no increased chance of birth defects. 1
• Ondansetron is a selective 5-HT3 serotonin-receptor antagonist dosed at 8 mg every 12 hours orally or 4 mg intravenously, with 16 mg the maximum single intravenous dose because of QTc prolongation risk, and headache, fatigue, dry mouth, malaise, and constipation each affecting more than 10% of adults. 2
• Promethazine is a phenothiazine with antidopaminergic, antihistamine, and anticholinergic properties, with an average effective adult antiemetic dose of 25 mg repeated at 4 to 6 hour intervals, and a boxed warning that it may cause serious tissue injury on injection including gangrene. 3
• Taking promethazine during pregnancy is not expected to increase the chance of birth defects, though some reports suggest that use late in pregnancy might increase the chance of slowed breathing in newborns. 4
• Nausea and vomiting affects about 8 out of 10 pregnancies and usually resolves between 12 and 16 weeks, while the most severe form, hyperemesis gravidarum, occurs in up to 3 out of 100 pregnancies with weight loss and dehydration. 5

Which option makes sense?

Options in this comparison can differ substantially in suitability. Please consult your healthcare provider to interpret the evidence, limitations, and cautions before choosing an option or changing your plan.

Disclosure: Pregnancy Smart makes supplements in this category. The comparison above is written to inform, not to steer readers toward or away from our brand.