Flu Medications


The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.


The flu can cause serious effects in both you and your baby. The benefits of treatment with antiviral medications, particularly oseltamivir, outweigh potential risks.

What Is antiviral medication?

Antiviral medications are used to fight against the flu when you have been infected by the influenza virus.  They are only available by prescription from your doctor or healthcare provider. There are 3 types of antiviral medications that are approved by the FDA and recommended by the CDC to treat the flu during the 2016-2017 season. These include: oseltamivir (Tamiflu), zanamivir (Relenza), and peramivir (Rapivab). Generic oseltamivir is available as either a liquid or capsule.  Only the brand name version of Relenza is available, and it is in the form of a powder that is inhaled. Rapivab is also only available as a brand name medication. It is an intravenous medication that is given by a healthcare professional in the hospital if you have a severe case of the flu.  There are other antiviral medications available, which include amantadine (Symmetrel) and rimantadine (Flumadine). However, these are not currently recommended by the CDC to treat and prevent flu because the influenza virus is resistant to these medications, making them ineffective.         

Antiviral medications are used to treat:

Antiviral medications are used to treat or prevent the flu. The flu is a viral infection caused by the influenza virus.  Antiviral medications are different than antibiotics, which kill bacteria that cause bacterial infections. Your doctor will be able to determine whether your infection is bacterial or viral, and provide you with the proper treatment. Antiviral medications are also different than other medications you can purchase over-the-counter at pharmacies, such as Tylenol Cold & Flu. These over-the-counter medications do not target the flu virus and will not lessen the severity of your infection. They only help to relieve some of your symptoms by reducing fever, decreasing congestion and cough, or relieving headaches or pain you may be experiencing from body aches associated with the flu.

Antiviral medications can also be used to prevent the flu in certain cases.  However, the CDC does not recommend seasonal prevention of the flu with antiviral medications except in certain circumstances. Instead, the influenza vaccine is recommended for prevention. You can read more about the flu shot during pregnancy here.

How do I know if I have the flu?

You might have the flu and not just a common cold if you have a fever and severe aches in joints and muscles.  Other symptoms of the flu include: weakness, extreme fatigue, headache, dry cough, runny nose, sore throat, pain around your eyes, and warm, flushed skin. Vomiting and diarrhea can also be symptoms of the flu, but they are not as common in adults. You should contact your doctor if you have severe vomiting, dizziness, difficulty breathing, confusion, or pressure or pain in your chest or stomach because these could be signs that your illness is severe.

How do antiviral medications work?

Antiviral medications prevent the influenza virus from spreading and infecting other cells in your body.  This can reduce the severity of your symptoms and shorten the length of time that you are sick by about 1 to 2 days. They also decrease the likelihood that you will have serious flu complications, such as pneumonia. Antiviral medications are important for treatment if you have a higher risk for flu complications because they can limit your infection to a mild illness and prevent the flu from progressing to severe illness that would require treatment in a hospital. Expecting moms and moms who are within 2 weeks postpartum are at a higher risk for flu complications.  You can read more about the dangers of the flu during pregnancy here.

If I am taking an antiviral medication, can it harm my baby?

Although evidence for the safety of antiviral medications during pregnancy is limited, the benefits of these medications for treating the flu outweigh potential risks. Influenza and fever can cause harm to your baby. In addition to the potential risks that the flu has on your baby, expecting moms have been shown to be more likely to require hospitalization and may be at a higher risk for death from the flu. Fever during the first trimester of pregnancy has been associated with a 2 times higher risk of birth defects of the brain, spine, or spinal cord. During labor, fever has been associated with causing health problems in the baby, including seizures, encephalopathy (brain disease or damage), cerebral palsy, and death.

The CDC recommends that expecting moms and moms who are within 2 weeks postpartum who have the flu should be treated with antiviral medications. Treatment should be started as soon as possible because treatment provided within the first 48 hours provides the most benefit. Oseltamivir is currently the preferred medication in pregnancy because it has the most safety data available for use during pregnancy. The CDC has stated that evidence does not suggest an increased risk of birth defects with the use of oseltamivir or zanamivir during pregnancy. Peramivir has not been studied in pregnancy, so its effects on the baby are unknown.


A recent study published in 2017 looked at 5,824 expecting moms who took either oseltamivir or zanamivir. It was found that there was no increased risk of birth defects, preterm birth, low birth weight, small for age at birth, stillbirth, or death in babies exposed to these medications.

A study that analyzed 337 expecting moms who took oseltamivir also found no increased risk of preterm birth or death of the baby. When the study looked at the first trimester, 1 baby was found to have a birth defect. The study concluded that there was not a significant association with oseltamivir and birth defects.

A review that looked at 2,926 expecting moms who took oseltamivir concluded that it was unlikely to cause health problems in the baby. There were 81 reported birth defects in babies exposed to oseltamivir, but these were not determined to be caused by oseltamivir.

Several other studies have not found an increased risk of adverse effects in babies exposed to either oseltamivir or zanamivir during pregnancy. These include a study that looked at 619 expecting moms who took oseltamivir and 50 expecting moms who took zanamivir, and another study that analyzed 1,237 expecting moms who took oseltamivir.

There is very little evidence available on amantadine. There have been 3 reports of heart defects in babies exposed to amantadine and 5 other reports of birth defects. Due to potential risks to your baby and lack of evidence, amantadine should be avoided, especially during the first trimester of pregnancy. There have been no reports on the use of rimantadine during pregnancy. Neither amantadine nor rimantadine are recommended by the CDC to treat influenza.  

Bottom line: Influenza should be treated in pregnant women due to the increased risk of complications in both the mom and baby. Oseltamivir is the preferred medication in pregnancy and is not associated with birth defects.

If I am taking an antiviral medication and become pregnant, what should I do?

If you become pregnant while taking an antiviral medication, you should contact your doctor immediately. Your doctor will likely continue your antiviral medication until the end of your treatment period, but adjustments to which antiviral you are taking may be recommended.

If I am taking an antiviral medication, can I safely breastfeed my baby?

The CDC states that breastfeeding does not need to be
discontinued if a mom is taking antiviral medications. There is no data available on the safety of oseltamivir, zanamivir, or peramivir in the breastfed infant; however, oseltamivir and zanamivir are considered acceptable while breastfeeding. Although there is no evidence of the safety of these medications in the breastfed infant, it is likely that the amount of drug that would be passed to the baby in breast milk is small.

Babies are at a high risk for severe illness from the flu. The CDC recommends that moms who have the flu are temporarily separated from their baby. The mom can pump her breast milk for her baby, and a healthy family member or healthcare professional can care for the baby while the mom is recovering. If temporary separation is not possible, moms should practice proper hand hygiene and wear a facemask before nursing or when coming into contact with their baby.

Bottom line: Antiviral medications can be continued while breastfeeding, although you should always ask your doctor before using any medications when nursing. If you are sick, it is recommended to pump your breast milk and have a family member care for your baby until you recover.

If I am taking an antiviral medication, will it be more difficult to get pregnant?

There are no studies reviewing the effects of antiviral medications on fertility.

If I am taking an antiviral medication, what should I know?

Treatment with antiviral medications is recommended if you are pregnant or within 2 weeks postpartum. Oseltamivir is the preferred medication during pregnancy, and its use has not been associated with birth defects. Treatment with antiviral medications outweighs potential risks because the flu can be very dangerous to both you and your baby.

If you have a fever during pregnancy, you should contact your doctor immediately. Fever has been associated with an increased risk of birth defects during the first trimester of pregnancy. Your doctor will suggest an appropriate medication to reduce your fever.

Antiviral medications can be continued while breastfeeding. Moms who catch the flu while breastfeeding should contact their doctor immediately. It is recommended to pump your breast milk and have a family member care for your baby until you recover.   

If I am taking any medication, what should I know?

This report provides a summary of available information about the use of antiviral medications to treat or prevent influenza during pregnancy and breastfeeding. Content is from the product label unless otherwise indicated.

You may find Pregistry's expert report about vaccines during pregnancy here, reports about a variety of vaccines here, and reports about the various medications used for infections here.   Pregistry also offers blog posts about vaccines here

Read the whole report
General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.