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Side Effects of Anti-Nausea Drug Zofran

The drug Zofran® , also known as Ondansetron, is approved by the Food and Drug Administration to treat nausea and vomiting resulting from chemotherapy treatment for cancer and after being administered anesthetic during surgery. The medication works by blocking serotonin, a natural substance in the human body, which can cause vomiting, It is manufactured by pharmaceutical giant GlaxoSmithKline and is also available as a generic. The medication comes both in pill form, as a liquid and as an injection.

When the FDA approved the drug for generic manufacture in 2006, Zofran was the 20th most frequently sold prescription medication in the United States, according to the Food and Drug Administration (FDA) website. In 2005, sales of the medication totalled $839,256,543.

Common Side Effects of Zofran

Zofran has side effects, including the following:

  • Diarrhea
  • Headache
  • Fever
  • Dizziness
  • Sleepiness
  • Constipation
  • Rash
  • Blurred vision
  • Muscle spasms
  • Accelerated heartbeat
  • Rash
  • Weakness

Severe Side Effects of Zofran

The common side effects above are not usually life- threatening.  However, Zofran has also been shown to have more serious consequences that include:

  • Abnormal heart electrical signals
  • Abnormal liver function tests
  • Abnormally low blood pressure
  • Acute liver failure
  • Bronchospasm
  • Decreased oxygen in the tissues or blood
  • Extrapyramidal reaction
  • Fast heartbeat
  • Giant hives
  • Life-threatening allergic reaction
  • Prolonged q-t interval on ekg
  • Shock
  • Slow heartbeat
  • Stevens-Johnson syndrome
  • Temporary blindness
  • Toxic epidermal necrolysis
  • Trouble breathing
  • Very rapid heartbeat – Torsades de pointes
  • Vocal cord swelling

Drug Interactions With Zofran

In addition to causing sometimes-severe side effects, Zofran is known to have negative interactions with other prescription drugs and common supplements.  These include medications for

  • Breathing problems
  • Cancer
  • Chest pain
  • Depression or other mental or mood problems
  • Fluid retention
  • High blood pressure
  • Immune system suppression
  • Infections
  • Irregular heartbeat
  • Nausea or vomiting
  • Pain
  • Sleep problems
  • Stomach or bowel problems
  • Swelling
  • Tourette syndrome

In addition to being used for nausea and vomiting after chemotherapy, radiation treatments or surgery, Zofran is also used off-label to treat severe morning sickness in pregnant women.  This use of the drug has been controversial, and we will discuss issues related to off-label use in future blog posts.


Zofran® is a registered trademark of GlaxoSmithKline, PLC.

Do not stop taking medications except on your doctor’s advice.