The nausea medication Zofran has been accused of causing severe birth defects in unborn children. While traditionally used to treat nausea and vomiting in chemotherapy patients, doctors often prescribe it for the off-label purpose of treating morning sickness in pregnant women.

Released in 1991, Zofran is manufactured by GlaxoSmithKline and was approved by the U.S. Food and Drug Administration (FDA) to treat nausea in chemotherapy or recent surgery patients.

Despite never receiving official approval from the FDA, Zofran has become quite popular for treating extreme cases of morning sickness conditions such as hyperemesis gravidarum, which can potentially cause dehydration and malnutrition in mothers.

While it is not illegal for physicians to prescribe medications for off-label purposes, it is illegal for drug companies to market them for such uses, which GlaxoSmithKline allegedly did with Zofran, after seeing how often physicians prescribed it to suffering mothers contending with morning sickness.

To tap into this market, GlaxoSmithKline allegedly promoted Zofran and other drugs for numerous off-label uses, which landed the company in hot water.

In 2012, GSK settled a federal, civil false claim lawsuit alleging GSK had promoted Zofran for the treatment of morning sickness in pregnant women despite being approved only for post-operative nausea, and that GSK had paid doctors kickbacks for prescribing Zofran. In 2012, GSK settled that lawsuit along with three similar lawsuits regarding other GSK products for $1.043 billion.

Beyond the false advertising claims, former and current Zofran patients have filed Zofran lawsuits against GlaxoSmithKline for allegedly causing their children to be born with birth defects.

Recent research supports these allegations, such as a Danish study that had examined approximately 900,000 births that occurred from 1997 to 2010. The study found that women who had taken Zofran during their pregnancy were twice as likely to have their baby born with heart defects.

Despite these findings, the U.S. Food and Drug Administration recently rejected a petition to change Zofran’s drug category, saying in an October 2015 statement that these studies “do not support a determination that there is an increased risk of fetal adverse outcomes.”

Zofran works by blocking the signals of nausea and vomiting to the brain.

For this reason, pregnant women with severe morning sickness are also often prescribed Zofran, which means that the unborn baby is exposed to this drug during the first trimester of pregnancy, when morning sickness is typically most severe.

The FDA recently issued a statement that it is conducting an ongoing investigation of the safety of Zofran (ondansetron, ondansetron hydrochloride and their generics). “Ondansetron may increase the risk of developing abnormal changes in the electrical activity of the heart, which can result in a potentially fatal abnormal heart rhythm.”

Due to the fact that Zofran is prescribed to pregnant women during the first trimester, the unborn fetuses are at high risk for birth defects, since this is the most crucial stage of development for the fetus. The FDA wants all doctors to inform pregnant women about the risks of Zofran birth defects, before prescribing it to them.

GlaxoSmithKline admitted that Zofran was not tested in pregnant women prior to advertising it for morning sickness treatment. Medical experts state that in depth studies are needed, and that pregnant women should be prescribed alternative medications to treat their morning sickness.