Zofran Side Effects

Zofran side effects may include serotonin syndrome and abnormal heart rhythm. Some recent studies also suggest that Zofran may be associated with an increased risk of birth defects when used by pregnant women during their first trimester.

What is Zofran?

Zofran is an anti-nausea drug that belongs to a class of medications called selective 5-HT3 receptor antagonists. Zofran is approved for the treatment of nausea and vomiting due to cancer chemotherapy and also used to prevent and treat nausea and vomiting after surgery. While it has never been cleared to treat nausea and vomiting related to pregnancy, Zofran has also been widely used for this indication.

Serious Zofran Complications

Zofran has been linked to a serious condition called serotonin syndrome, which occurs when levels of serotonin become abnormally high. Symptoms of this life-threatening Zofran side effect include:

  • High fever
  • Irregular heartbeat
  • Seizures
  • Unconsciousness

In September 2011, the U.S. Food & Drug Administration (FDA) warned that Zofran might increase the risk of developing abnormal changes in the electrical activity of the heart, which can result in a potentially fatal abnormal heart rhythm. In December 2012, the agency announced that the 32-mg intravenous  dose of Zofran (the highest dose available) would no longer be marketed due to serious cardiac risks.

Patients taking Zofran should contact their doctor if they experience any of the following side effects:

  • Blurred vision or temporary vision loss
  • Severe dizziness, feeling short of breath, fainting, fast or pounding heartbeats
  • Slow heart rate, trouble breathing
  • Anxiety, agitation, shivering
  • Feeling like you might pass out
  • Urinating less than usual or not at all

Less serious Zofran side effects include:

  • Diarrhea or constipation
  • Weakness or tired feeling
  • Fever
  • Headache
  • Dizziness, drowsiness

Zofran and Birth Defects

About 80% of pregnant women are known to experience nausea and vomiting while they are expecting. While Zofran has never been approved for this indication, one recent analysis found that around 1 million expectant mothers in the U.S. are treated with the drug or a generic equivalent every year.

Zofran is currently classed by the FDA in Pregnancy Category B, which indicates that its effects on a developing pregnancy have not been well studied. However, some recent research has suggested that the use of Zofran during the first trimester of pregnancy may increase the risk that a baby will be born with serious birth defects, including:

Hundreds of lawsuits have been filed in U.S. courts on behalf of children who were allegedly born with Zofran-related birth defects. Plaintiffs claim that GlaxoSmithKline concealed evidence of this risk and failed to provide appropriate warnings to doctors and patients. They also point out that in 2012, Glaxo agreed to pay $3 billion to resolve illegal marketing charges with the U.S. Department of Justice that involved a number of its medications. Among other things, the company had been accused of illegally promoting Zofran as an off-label treatment for expectant mothers suffering from pregnancy-related nausea and vomiting.

Legal Help for Those Harmed by Zofran

Bernstein Liebhard LLP offers free legal reviews to alleged victims of Zofran-related birth defects. To learn more, please call (888) 994-5118 to discuss your case with one of our attorneys.

  1. FDA (2006) “Zofran Prescribing Information” http://www.fda.gov/ohrms/dockets/ac/06/briefing/2006-4254b_06_06_KP%20Ondansetron%20FDA%20label%208-22-06.pdf,
  2. FDA (September 2011) “FDA Drug Safety Communication: Abnormal heart rhythms may be associated with use of Zofran (ondansetron)” http://www.fda.gov/Drugs/DrugSafety/ucm271913.htm
  3. FDA (December 2013) “FDA Drug Safety Communication: New information regarding QT prolongation with ondansetron (Zofran)” http://www.fda.gov/Drugs/DrugSafety/ucm310190.htm
  4. NEJM (February 2013) Ondansetron in Pregnancy and Risk of Adverse Fetal Outcomes” http://www.nejm.org/doi/full/10.1056/NEJMoa1211035
  5. Clinical Endocrinology News (October 2014) “Ondansetron: New and Troubling Data” http://www.clinicalendocrinologynews.com/index.php?id=12242&type=98&tx_ttnews%5Btt_news%5D=221089&cHash=da03e20e36
Last Modified: July 22, 2016

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