Ondansetron: Risk of Birth Defects

Drug Safety Update

Ondansetron is a 5HT₃-receptor antagonist indicated for

• Prevention of nausea and vomiting induced by chemotherapy and radiotherapy.
• Prevention and treatment of postoperative nausea and vomiting.

Epidemiological studies have identified a small increased risk of cleft lip and/or cleft palate in babies born to women who used oral ondansetron during the first 12 weeks of pregnancy. However, there were conflicting results of cardiac malformations.

• Association of Maternal First-Trimester Ondansetron Use With Cardiac Malformations and Oral Clefts in Offspring, 2018
  
• Ondansetron for Treatment of Nausea and Vomiting of Pregnancy and the Risk of Specific Birth Defects, 2018
  
• Ondansetron use in the first trimester of pregnancy and the risk of neonatal ventricular septal defect, 2020
  

Recommendations

The use of ondansetron during pregnancy is not recommended.

If there is a clinical need for ondansetron in pregnancy, patients should be counselled on the potential benefits and risks, and the final decision made jointly.

External Link

• Ondansetron: Information updates on risk of birth defects, 2021