What to Know About Taking Zofran for Morning Sickness

Medically Reviewed by Traci C. Johnson, MD on July 14, 2023
3 min read

Ondansetron, marketed under the name Zofran, is a medicine that is primarily given to patients to help stop nausea and vomiting caused by cancer treatments. This medicine is also used to help manage morning sickness during pregnancy. Here’s what you need to know if you’re taking Zofran for morning sickness.

Zofran is a drug that blocks the effects of serotonin. Serotonin is a hormone and neurotransmitter that is believed to help manage your appetite, digestion, mood, social behavior, sleep, and other functions.

Zofran's original use was to help relieve nausea and vomiting in people with cancer caused by chemotherapy. Doctors may also prescribe Zofran for nausea and vomiting caused by:

  • Anesthesia
  • Radiation therapy
  • Surgery 

Another use for ondansetron that is growing in popularity is to help relieve the symptoms of morning sickness in pregnant women. It’s so popular that it’s estimated that one in four pregnant women are prescribed Zofran for morning sickness. One of the benefits of this medication is that it can prevent you from becoming dehydrated or losing weight due to nausea and vomiting.

There are three different ways that Zofran can be given for nausea and vomiting in pregnancy (NVP). The most common way to take Zofran is orally in the form of a quick-dissolving tablet. It can also be injected into your muscle or through an IV.

Zofran is approved by the Food and Drug Administration (FDA) for use to fight off nausea related to chemotherapy. It is not currently approved by the FDA for morning sickness. Even so, most studies show that ondansetron is safe to use during the first trimester when most women experience morning sickness.

Major birth defects. Studies show that taking Zofran during the first trimester of pregnancy does not lead to any major birth defects. One study conducted by the Centers for Disease Control (CDC) and Sloane Epidemiology Center at Boston University showed that nearly 70% of pregnant women had morning sickness during the first trimester. Those who took Zofran did not have an increased risk of major fetal birth defects.

A Danish study published in The New England Journal of Medicine in 2013 showed that Zofran did not increase the risk of the following in most pregnancies:

  • Low birth weight
  • Pre-term delivery
  • Infants who were small for their gestational age (how many weeks into your pregnancy)
  • Major birth defects
  • Being born stillborn
  • Miscarriage (loss of pregnancy before 20 weeks)

Cleft palate and heart defects. While most doctors agree that using Zofran in early pregnancy is safe and likely won't cause major birth defects, newer studies show that there might be a slight risk for other complications. The same CDC study shows that there might be an increased risk of cleft palates and heart defects in babies who were exposed to Zofran during pregnancy. Statistics put the risk at less than 3 in every 10,000 births of babies who were exposed to Zofran.

It’s important to remember that this study acknowledges that more research needs to be done to make any definite claims. The Danish study also agrees that more research is needed to confirm their findings, as well.

Maternal heart issues. In September 2011, the FDA gave a warning that taking Zofran might increase your risk of maternal heart issues. Namely, QT prolongation and torsade de pointes. Both of these conditions cause irregular heartbeats, and torsade de pointes can even have fatal outcomes.

As with any medication that is considered safe, Zofran does still have some possible side effects. Common side effects can include:

  • Drowsiness
  • Feeling tired
  • Chills
  • Headache
  • Constipation
  • Weakness

If you experience any of these serious side effects, you should contact your doctor immediately:

  • Rash, itching, swelling, or hives
  • Chest pain
  • Dizziness
  • Shortness of breath
  • Fever
  • Seizures

There are some other ways that you can deal with morning sickness. The first way is by slightly changing your diet to avoid any foods that might trigger nausea for you. Studies show that nine out of ten women can manage their symptoms of morning sickness simply by tweaking what they eat.

Some doctors recommend taking a vitamin B6 supplement. Vitamin B6 helps to reduce nausea in small amounts. It’s important not to take more than 100 milligrams each day to avoid side effects like temporary nerve damage. Ginger can also help reduce nausea. Formulas or natural supplements with ginger may help relieve your morning sickness symptoms.