Zofran (ondansetron) is an antinausea drug frequently used to mitigate the effects of cancer treatments, including chemotherapy and radiation therapy. It has also been used as an off-label treatment for morning sickness, although such use is controversial and may lead to birth defects.

Zofran Development and Significance

Originally developed in the 1980s by the English pharmaceutical company GlaxoSmithKline, Zofran was later approved in the United States by the FDA. Upon the drug’s U.S. patent expiration in 2006, it was the 20th highest-selling brand name drug in the country. In 2015, GlaxoSmithKline’s oncology division was sold to Novartis, who acquired the trademark rights to Zofran as part of the transaction. Other companies sell ondansetron – the active ingredient in Zofran – under various other names. In the U.S., the second-most common brand name for ondansetron is Zuplenz.

The World Health Organization has included ondansetron on it’s list of essential medicines needed for a country’s basic health-care system. Since the patent on ondansetron expired more than a decade ago, it is available in many generic forms throughout the world.

Zofran Dosage and Medical Information

While Zofran is most commonly prescribed during cancer treatment, it may also be used to prevent nausea and vomiting during or after surgery. As a prophylactic treatment, Zofran is typically given to the patient approximately 30 minutes before their cancer treatment or 1 hour before being given anesthesia in preparation for surgery. It will usually be administered for up to 8 hours after the cancer treatment or surgery.

Morning Sickness

Although it has not been approved by the FDA for use by pregnant women in combating pregnancy-related nausea, Zofran has been prescribed by many doctors as an off-label treatment for morning sickness. Worldwide attention was brought to this off-label use of Zofran in 2012 and 2014 when Kate Middleton, the wife of Prince William of England, was prescribed the drug for each of her two pregnancies. The risks of Zofran for pregnant women and fetuses are disputed and still largely unknown. The FDA has stated that studies have reported “inconsistent outcomes,” and that many of the studies have problems with their methodologies that prevent the agency from making a determination about Zofran’s safety.

Off-Label Uses of Zofran

According to a 2013 study published in the Journal of Clinical Outcomes Management, ondansetron is prescribed frequently in hospitals for reasons other than to prevent nausea and vomiting related to treatment of cancer or surgery. The study indicated that elderly patients were more likely to receive ondansetron than standard antiemetic treatment in hospital settings, despite a lack of evidence suggesting its effectiveness at treating nausea and vomiting over other drugs. Separately, a 2006 study looked at the effects of Zofran on children who visited a pediatric emergency department with gastroenteritis (a viral infection that can cause diarrhea and vomiting) and dehydration. According to the results of the study, children who took Zofran were less likely to vomit, and those who vomited did so fewer times than those who took a placebo.

Zofran Drug Details

BRAND NAME Zofran, Zofran ODT, Zuplenz

GENERIC NAME ondansetron, ondansetron hydrochloride


MANUFACTURER Novartis/GlaxoSmithKline (Zofran), MidaTech Pharma (Zuplenz), others (generic)

COMMON DOSAGES 4 mg (children), 8 mg, 16 mg, 24 mg

FDA HISTORY First approved in 1991; label updated in September 2016

Zofran Side Effects and Risks

There are a number of safety concerns related to ondansetron. The most common Zofran side effects, according to the FDA, are headache, fatigue, constipation, and diarrhea. However, much more severe conditions can result from taking Zofran, including serotonin syndrome and arrhythmia, each of which can result in death.

Some of the most severe side effects include:

  • Serotonin Syndrome – A severe medical condition caused by the physiological effects of blocking serotonin in the brain.
  • Abnormal Hearth Rhythms – Zofran can affect the heart’s QT interval (electrical cycle), in turn affecting the rhythm of the heart and potentially causing death.
  • Birth Defects – Zofran can cause birth defects in the fetuses of women who take the drug while pregnant.

These are just a few of the most severe side effects of Zofran. Get more information about Zofran side effects, complications, and interactions here.

Zofran Lawsuits

GlaxoSmithKline is the subject of hundreds of zofran lawsuits due to the drug’s severe side effects, including the risk of birth defects. In 2015, Novartis purchased the oncology division of GlaxoSmithKline, and as a result Novartis is now also named as a defendant in lawsuits claiming Zofran-related damages after March 23, 2015.