Ondansetron

The Basics

What is Ondansetron?

Used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, and surgery.

Brand names for Ondansetron

Zofran

How Ondansetron is classified

Antiemetics, Serotonin Antagonists

Ondansetron During Pregnancy

Ondansetron pregnancy category

Category N/ANote that the FDA has deprecated the use of pregnancy categories, so for some medications, this information isn’t available. We still think it’s useful to list historical info, however, given what a common proxy this has been in the past.

What we know about taking Ondansetron while pregnant

Available data do not reliably inform the association of ZOFRAN and adverse fetal outcomes. Published epidemiological studies on the association between ondansetron and fetal outcomes have reported inconsistent findings and have important methodological limitations hindering interpretation (see Data). Reproductive studies in rats and rabbits did not show evidence of harm to the fetus when ondansetron was administered during organogenesis at approximately 6 and 24 times the maximum recommended human oral dose of 24 mg/day, based on body surface area, respectively (see Data). The background risk of major birth defects and miscarriage for the indicated population is unknown. In the US general population, the estimated background risk of major birth defects and miscarriages in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

Taking Ondansetron While Breastfeeding

What are recommendations for lactation if you're taking Ondansetron?

Little published information is available on the clinical use of ondansetron during breastfeeding, although it is apparently frequently used for nausea after cesarean section, usually in doses of 4 to 8 mg intravenously.[1][2] Use after cesarean section appears to not affect the onset of breastfeeding.[3] No adverse infant effects have been reported and the drug has been used in infants.[4] An alternate drug may be preferred, especially while nursing a newborn or preterm infant.

Maternal / infant drug levels

Little published information is available on the clinical use of ondansetron during breastfeeding, although it is apparently frequently used for nausea after cesarean section, usually in doses of 4 to 8 mg intravenously.[1][2] Use after cesarean section appears to not affect the onset of breastfeeding.[3] No adverse infant effects have been reported and the drug has been used in infants.[4] An alternate drug may be preferred, especially while nursing a newborn or preterm infant.

Possible effects of Ondansetron on milk supply

A randomized, double-blind study compared placebo to intravenous ondansetron 4 mg given after cesarean section as prophylaxis for postoperative nausea and vomiting. There was no difference in the time of the first breastfeeding between the two groups.[3]

Possible alternatives to Ondansetron

Metoclopramide, Prochlorperazine.