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Zofran FDA Warnings


The popular anti-nausea drug Zofran may increase a pregnant woman’s risk of deadly heart problems and serotonin syndrome, according to the FDA. Studies also suggest it may increase the risk of birth defects.

FDA Warning: Zofran and Pregnancy

Zofran is classified as a “Pregnancy Category B” medication by the FDA. This means it did not cause birth defects in animal studies, but the risk in humans is unknown. Zofran is not FDA-approved or recommended for pregnant women.

In recent years, Zofran has become more popular than ever as an “off-label” treatment for morning sickness. Unfortunately, a growing number of studies suggest it may also increase the risk of birth defects by as much as 30%, according to one study involving 900,000 pregnancies in Denmark.

At least two studies have found that Zofran doubles the risk of having a baby with a heart defect. Another study has found that Zofran more than doubles the risk of cleft palate in newborns.

FDA Warning: Zofran and Abnormal Heart Rhythms

September 2011 — The FDA has published a Safety Warning for Zofran and the risk of abnormal heart rhythm due to changes in electrical activity in the heart.

Pregnant women use Zofran to treat severe vomiting, which can also cause electrical changes in the heart due to fluid loss. It is possible that pregnant women could be at greater risk of this side effect from Zofran, but the FDA did not specifically address this risk because Zofran is not approved for use during pregnancy.

Zofran heart risks may include:

  • Abnormal heart rhythm
  • QT interval prolongation
  • Heart palpitations or “fluttering”
  • Cardiac arrest
  • Torsades de Pointes
  • Sudden death

Zofran Recalled Over Heart Concerns

The 32-mg intravenous (IV) single dose of Zofran was recalled by the FDA in June 2012. The agency was concerned that the highest dose of Zofran could significantly increase the risk of heart problems.

FDA Warning: Serotonin Syndrome and Zofran

The FDA warned about a “possible increased risk” of serotonin syndrome from Zofran in March 2013.

Zofran treats nausea by speeding up gastric emptying. It is a 5-HT3 receptor blocker, which means it works by selectively blocking serotonin signaling in certain parts of the brain.

The warning is concerning for pregnant women because up to 14% use antidepressants during pregnancy. The most popular antidepressants, selective serotonin reuptake inhibitors (SSRIs), work by changing serotonin levels in the mother’s brain.

It is possible that pregnant women on SSRIs and Zofran could be at risk of problems involving the serotonin signaling. Unfortunately, serotonin syndrome is a life-threatening condition that is easily misdiagnosed because its symptoms resemble many other conditions.

Serotonin syndrome symptoms:

  • Confusion
  • Agitation or restlessness
  • Dilated pupils
  • Headache
  • Changes in blood pressure and/or temperature
  • Nausea and/or vomiting
  • Diarrhea
  • Rapid heart rate
  • Loss of muscle coordination
  • Shivering
  • Sweating

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