Taking Zofran during pregnancy is low risk. That said, Zofran for pregnancy nausea is an off-label use and may cause side effects. There might be better options.

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Photography by Aya Brackett

Big meals and spicy foods — no. Saltine crackers, dried ginger, and an afternoon nap — yes. You’ve tried all the tricks, and you’re still nauseous and struggling with pregnancy morning sickness. When you mention it to your doctor, they suggest medication.

You trust your doctor, but you still want to verify: Can Zofran help get rid of this awful feeling without causing any harmful side effects?

Keep reading to learn more about taking Zofran during pregnancy.

Nausea and vomiting in pregnancy typically occur in the first trimester and are very common. You’re probably interested in how to stop the awful feeling, especially if you feel like you’ve tried every trick in the book. Enter Zofran.

Zofran is the trade name for ondansetron. It’s a drug that blocks the action of serotonin, a naturally occurring substance that can lead to nausea and vomiting.

It was originally used to treat nausea associated with chemotherapy or surgery. It’s still used and approved by the Food and Drug Administration (FDA) for this purpose. But now, Zofran has also become a frequently prescribed drug to reduce nausea and vomiting in pregnancy.

In fact, the Centers for Disease Control and Prevention (CDC) reports that the off-label use of ondansetron for nausea in pregnancy — meaning that it’s not FDA-approved for this purpose — went from about 1 in 100 before 2000 to about 1 in 10 by 2011.

Morning sickness can probably be blamed on human chorionic gonadotropin (hCG), a hormone released by the placenta. When the nausea and vomiting become so bad they lead to weight loss and dehydration, your doctor may diagnose you with hyperemesis gravidarum and prescribe other medications.

The general, researched-baked consensus of the past was that Zofran is relatively safe in all trimesters. However, now some people suggest otherwise.

One recent meta-analysis of eight studies suggested that exposure to ondansetron in the first trimester could cause a very small increase in the risk of heart defects and orofacial malformations like cleft palate in babies.

On the other hand, quoting a study from 2018, the CDC found that taking ondansetron in early pregnancy didn’t seem to be linked to the likelihood of having a baby with a health problem at all.

The Food and Drug Administration (FDA) agrees with the CDC. It points out that the available data don’t make a reliable correlation between ondansetron and an increase in the risk of heart defects and orofacial malformations.

According to the FDA, other factors could have played a role in the reported health issues. For example, people with severe nausea are more likely to have metabolic changes and nutritional deficiencies, which could put their babies at a higher risk of these issues.

Regarding the meta-analysis that suggested a connection between ondansetron and heart defects or cleft palate, it’s important to note that the reported absolute increase in risk was small. The increased risk was 0.03 percent for cleft palate and 0.03 percent for heart defects.

Still, these risks seem to be highest in the first trimester, when the incidence of severe nausea and vomiting is also much greater. For this reason, some physicians are starting to prescribe Zofran less and less.

In addition, given that the FDA approved a new medication for morning sickness — Bonjesta — off-label Zofran is becoming less frequently prescribed due to the possible liability risk. All this points to a risk that the medical community recognizes as small but existent.

People with an electrolyte imbalance caused by severe nausea and vomiting shouldn’t take Zofran. This may be due to the risk of serotonin syndrome, a condition in which serotonin levels accumulate in the body.

If you’re on antidepressants or other medications that affect serotonin levels, you shouldn’t take Zofran.

Oftentimes, morning sickness is considered par for the pregnancy course. Still, severe cases of nausea and hyperemesis gravidarum come with their own risks.

The American College of Obstetricians and Gynecologists reports that complications from hyperemesis gravidarum can lead to malnutrition and micronutrient deficiency, which can put your pregnancy at risk. Thus, in severe cases of nausea, your OB-GYN may prescribe Zofran (or Bonjesta, a newer drug).

The dose of Zofran for hyperemesis gravidarum requiring hospitalization is a maximum of 10 milligrams via intravenous therapy (IV) every 8 hours.

More typical pregnancy nausea is managed by a much lower oral dose — 4 to 8 mg every 8 hours. Always follow your doctor’s directions for taking Zofran.

Remember that Zofran isn’t approved for pregnancy nausea, so the manufacturer doesn’t provide specific dosage instructions for this use.

Bonjesta is generally prescribed at a daily dose of one extended-release tablet, which contains 20 mg of doxylamine succinate and 20 mg of pyridoxine hydrochloride, or two tablets per day for more severe cases.

Most medications have side effects. Side effects associated with Zofran include:

  • headache
  • diarrhea
  • constipation
  • weakness
  • tiredness
  • dizziness

It’s unknown whether Zofran passes into the milk of nursing mothers, but it’s found in the breast milk of rats.

Whether you decide to take Zofran is a choice you’ll make after a discussion with your OB-GYN. Because of the small risks, especially in the first trimester, your doctor may prescribe an alternative.

In the meantime, when the nausea wells up, remember that it’s all for a good cause and should pass around the time you enter the second trimester. If it doesn’t, talk to your doctor — you may need other medications for relief.