This sheet is about exposure to antiviral medications in pregnancy and while breastfeeding. This information is based on published research studies. It should not take the place of medical care and advice from your healthcare provider.
What are antiviral medications?
Antiviral medications treat viral illnesses, such as influenza (the “flu”). Symptoms of the flu may include fever, headache, chills, muscle aches, coughing, congestion, runny nose, and sore throat. There can also be stomach upset with vomiting and diarrhea. For more information, see the MotherToBaby fact sheet on Seasonal Influenza (the Flu) at https://mothertobaby.org/fact-sheets/seasonal-influenza-the-flu-pregnancy/.
What do antiviral medications do?
Antiviral medications can lessen the symptoms of the flu and lower the risk of serious illness. Some may be used to help prevent a person from catching the flu. There are 4 antiviral medications approved by the U.S. Food and Drug Administration (FDA) to treat the flu: oseltamivir (Tamiflu®), peramivir (Rapivab®), zanamivir (Relenza®), and baloxavir (Xofluza®). You need a prescription from your healthcare provider to get these medications.
Sometimes when women find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take your medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy.
According to the Centers for Disease Control and Prevention (CDC), oral oseltamivir is the preferred treatment during pregnancy. Also, baloxavir is not recommended for the treatment of the flu during pregnancy or while breastfeeding, due to a lack of information. Your healthcare provider can discuss what treatment is best for you.
Can I skip getting the flu vaccine and just take one of these medications if I get sick?
Antiviral medications are not a substitute for the flu vaccine. Women who are pregnant have a higher chance of complications from the flu. Women who are pregnant or planning to get pregnant should get the injected form of the flu vaccine (flu shot). The nasal-spray form of the influenza vaccine has not been recommended during pregnancy. For more information, see the MotherToBaby fact sheet on the Seasonal Influenza Vaccine (Flu Shot) at https://mothertobaby.org/fact-sheets/seasonal-influenza-vaccine-flu-shot-pregnancy/.
I take an antiviral medication. Can it make it harder for me to get pregnant?
There are no human studies on the use of oseltamivir, peramivir, zanamivir, or baloxavir and female fertility (ability to get pregnant).
Does taking an antiviral medication increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. Researchers have not found a higher chance of miscarriage after the use of oseltamivir. Limited information on zanamivir does not suggest an increased chance of miscarriage. Studies have not been done to see if exposure to baloxavir or peramivir in human pregnancy could increase the chance of miscarriage.
Does taking antiviral medication increase the chance of birth defects?
Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at research studies to try to understand if an exposure, like antiviral medications, might increase the chance of birth defects in a pregnancy.
Several studies that looked at the use of oseltamivir and zanamivir during pregnancy did not find an increased chance of birth defects. Studies have not been done in humans to see if exposure to baloxavir or peramivir could increase the chance of birth defects.
Does taking an antiviral medication in pregnancy increase the chance of other-pregnancy related problems?
Several studies have not found a higher chance of pregnancy complications with oseltamivir or zanamivir use during pregnancy. Studies have not been done in humans to see if exposure to baloxavir or peramivir could increase the chance of preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2,500 grams] at birth).
Does taking an antiviral medication in pregnancy affect future behavior or learning for the child?
Studies have not been done to see if oseltamivir, peramivir, zanamivir, or baloxavir can increase the chance of behavior or learning issues in a child.
I am pregnant and think I may have the flu. What should I do?
Talk to your healthcare provider as soon as possible. Women who are pregnant have a greater chance of complications from the flu. Taking an antiviral medication within 48 hours (the earlier the better) of your first symptoms can lower the chance of severe complications from the flu. The medications may still be helpful when they are started later than this, so talk to your healthcare provider even if you have already been sick for more than 2 days.
I am pregnant and my partner has the flu. Should I take an antiviral medication so that I don’t get sick?
Talk with your healthcare provider if you have been in close contact with someone who has the flu. Because women who are pregnant are at an increased risk of complications from the flu, some may benefit from taking antiviral medications. Your healthcare provider can help you decide whether taking an antiviral medication for flu prevention is best for you.
Be sure that you and others around you are doing the following to help prevent spread of the flu:
- Wash your hands with soap and water frequently
- Avoid touching your eyes, nose, or mouth
- Try to avoid close contact with sick people
- Cover your nose and mouth when you cough or sneeze
- Stay home and avoid close contact with others if you are sick
- Get your flu shot every year
Breastfeeding while taking antiviral medication:
Oseltamivir passes into breast milk in small amounts and has not been shown to cause side effects in nursing babies. Zanamivir is given by inhalation, which limits the amount of medication that gets into the bloodstream. For this reason, zanamivir is unlikely to enter breast milk in high amounts. Studies have not been done on the use of peramivir during breastfeeding. Because peramivir does not get absorbed well from the gut, it is unlikely that any medication that passes into the breast milk would enter the baby’s system. Studies have not been done on the use of baloxavir during breastfeeding. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a man takes an antiviral medication, could it affect his fertility or increase the chance of birth defects?
Studies have not been done in humans to see if oseltamivir, peramivir, zanamivir, or baloxavir could affect male fertility (ability to make healthy sperm) or increase the chance of birth defects. Illnesses that cause fever, such as the flu, might cause a temporary reduction in the movement or number of sperm which could make it harder to conceive a pregnancy during that time. Close contact may not be recommended when you have the flu to try to avoid passing the flu to your partner. In general, exposures that men have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet on Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
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