The anti-nausea drug Zofran has been linked to heart defects, including atrial septal defect (“hole in the heart”) in babies who were exposed to Zofran during pregnancy.

Zofran and Atrial Septal Defect

In June 2014, the Toronto Star reported on at least 20 Canadian women who used Zofran to treat morning sickness and had a baby with a birth defect.

In one case:

“A doctor reported that [Zofran] was the suspected cause of a baby’s mouth deformity, jaundice, heart murmur and two heart defects, including “atrial septal defect,” otherwise known as a hole in the heart.”

Zofran (ondansetron) is an anti-nausea drug approved for chemotherapy patients. It is often used “off-label” in pregnant women, despite a lack of safety studies.

In fact, the manufacturer of Zofran, GlaxoSmithKline (GSK), only tested Zofran in pregnant rats and rabbits in 1985. Even then, the animals were not given Zofran until the end of the first trimester — after a fetus is no longer at risk of major birth defects.

Studies Link Zofran and Atrial Septal Defect

In December 2014, Swedish researchers published a study linking Zofran and a doubled risk of septal heart defects. Results were based on about 1,349 pregnancies between 1998 and 2012 where Zofran was used in the first trimester. The study was published in Reproductive Toxicology.

In August 2013, a study involving nearly 900,000 pregnancies in Denmark (“Ondansetron use in early pregnancy and the risk of congenital malformations”) found that 4.7% of women who used Zofran during pregnancy had a baby with a birth defect. They concluded that Zofran increased the risk of birth defects by 30%, mostly due to heart defects.

What is Atrial Septal Defect?

Atrial Septal Defect (ASD) is also known as a “hole in the heart” defect. It involves holes in the septum (walls) that separate the left and right side of the heart.

All babies develop in the womb with holes in the heart, but they normally close just before birth or shortly afterward. If they do not, oxygen-depleted blood can mix with oxygen-rich blood, resulting in low oxygen levels in the child’s bloodstream.

Over time, too much blood can flow into the heart and damage delicate blood vessels, leading to pulmonary hypertension. ASD also causes the right side of the heart to work harder to force blood into the lungs. Eventually, the heart will weaken and may not pump well, leading to heart failure and death.


  • Heart murmur (hearing abnormal sound in the heart with a stethoscope)
  • Fatigue
  • Problems breathing
  • Frequent respiratory infections in children
  • Feeling the heart beat (palpitations)
  • Shortness of breath with activity
  • Failure to thrive


Mild atrial septal defects (less than 5-mm) rarely cause symptoms and may never need treatment. They may even close on their own as the child grows. However, large defects (8 to 10-mm) do not usually close on their own and frequently cause circulation problems.

Using a minimally-invasive technique called cardiac catheterization, doctors make a small incision in the patient’s groin and use a long, flexible tube called a catheter to carefully guide a “patch” into the hole in the heart. This patch remains in the heart permanently. When the catheter is removed, the surgery is complete.

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