Treating Flu with Antiviral Drugs

At a glance

  • Flu antiviral drugs are prescription medicines that can be used to treat flu illness.
  • They can lessen symptoms and shorten the time you are sick.
  • Antiviral drugs work best when started within 1 to 2 days after flu symptoms begin.
  • CDC recommends prompt treatment for people who have flu or suspected flu and who are at increased risk of serious flu complications, such as pregnant people, people with asthma and chronic lung disease, diabetes (including gestational diabetes), or heart disease.
antiviral used to treat flu

Treatment overview

Flu antiviral drugs are prescription medicines (pills, liquid, an inhaled powder, or an intravenous solution) that fight against flu viruses in your body. Antiviral drugs are not sold over the counter. You can only get them if you have a prescription from a health care provider. Antiviral drugs are different from antibiotics, which fight against bacterial infections. Antiviral drugs for flu only work to treat flu. Flu antiviral drugs are different than antiviral drugs used to treat other infectious diseases such as COVID-19. Antiviral drugs prescribed to treat COVID-19 are not approved or recommended to treat flu.

Treatment of flu with flu antiviral medications works best when started within 1-2 days after flu symptoms begin. Flu antiviral drugs can lessen symptoms and shorten the time you are sick by about a day. Starting antiviral treatment shortly after symptoms begin also can help reduce some flu complications. For adults hospitalized with flu, some studies have reported that early antiviral treatment can reduce the duration of hospitalization and their risk of death.

Recommended antiviral drugs for this flu season

There are four FDA-approved antiviral drugs recommended by CDC to treat flu this season.

  • oseltamivir phosphate (available as a generic version or under the trade name Tamiflu®),
  • zanamivir (trade name Relenza®),
  • peramivir (trade name Rapivab®), and
  • baloxavir marboxil (trade name Xofluza®).

Oseltamivir

Generic oseltamivir and Tamiflu® are available as a pill or liquid suspension and are FDA approved for early treatment of flu in people 14 days and older.

Zanamivir

Zanamivir is a powdered medication that is inhaled and approved for early treatment of flu in people 7 years and older. Note: Zanamivir (trade name Relenza®) is administered using an inhaler device and is not recommended for people with breathing problems like asthma or COPD. Oseltamivir and zanamivir are given twice a day for five days.

Peramivir

Peramivir is given once intravenously by a health care provider and is approved for early treatment of flu in people 6 months and older.

Baloxavir

Baloxavir is a pill given as a single dose by mouth and is approved for early treatment of flu in children 5 years to younger than 12 years who do not have any chronic medical conditions, and for all people 12 years and older. Note: Baloxavir (trade name Xofluza®) is not recommended for treatment of flu in pregnant people, lactating people, or in outpatients with complicated or progressive illness because there is no information about use of baloxavir in these patients. Baloxavir is also not recommended for treatment of flu in hospitalized patients due to limited data.

Who should take antiviral drugs

It's very important that flu antiviral drugs are started as soon as possible to treat patients who are:

  • hospitalized with flu,
  • people who are very sick with flu but who do not need to be hospitalized, and
  • people who are at increased risk of serious flu complications based on their age or underling health conditions, if they develop flu symptoms. For example, people with asthma and chronic lung disease, diabetes, or heart disease are at higher risk, as well as pregnant people.

Although patients with mild illness who are not at higher risk for flu complications may also be treated with antiviral drugs, most do not need to be.

Children

Children and flu antiviral drugs‎

Parents, if your child gets sick with flu, antiviral drugs offer a safe and effective treatment option. For treatment, flu antiviral drugs should ideally be started within two days after becoming sick and taken according to your doctor's instructions (usually for five days).

Children can take flu antiviral drugs, though this varies by medication. Oseltamivir is recommended by CDC for treatment of flu in children beginning from birth and the American Academy of Pediatrics (AAP) recommends oseltamivir for treatment of flu in children 2 weeks old or older.

  • Oseltamivir is available as an oral suspension for children.
  • Zanamivir is approved for early treatment of flu in people 7 years and older, though it is not recommended for use in children with underlying respiratory disease, including asthma and other chronic lung diseases.
  • Peramivir is approved for early treatment in people 6 months and older.
  • Baloxavir is available in a single dose tablet for children 5 years and older.

If your child's health care provider prescribes oseltamivir capsules for your child and your child cannot swallow capsules, but the pediatric liquid suspension is not available, the prescribed capsules may be opened, mixed with a thick sweetened liquid, and given that way.

Pregnant people

Oral oseltamivir is recommended for treatment of pregnant people with flu because compared to other recommended antiviral medications, it has the most studies available to suggest that it is safe and beneficial during pregnancy. Baloxavir is not recommended for pregnant people or while breastfeeding, as there are no available efficacy or safety data.

When antiviral drugs should be taken

Antiviral treatment provides the greatest benefit when started soon after flu illness begins. Studies show that flu antiviral drugs work best for treatment when they are started within two days of getting sick. However, starting them later can still be beneficial, especially if the sick person is at higher risk of serious flu complications or is in the hospital with more severe illness. Follow instructions for taking these drugs. Follow your doctor's instructions and the dose, frequency, and duration listed on the label instructions for taking these drugs.

How to get treatment

Check with your doctor promptly if you are at higher risk of serious flu complications (full list of people who are at higher risk) and you develop flu symptoms.

What not to do

Antibiotics will not treat flu

When antibiotics aren't needed, they won't help you, and their side effects could still cause harm. Side effects can range from mild reactions, like a rash, to more serious health problems. These problems can include severe allergic reactions, antimicrobial-resistant infections and C. diff infection. C. diff causes diarrhea that can lead to severe colon damage and death.

Possible side effects

Possible side effects vary for each flu antiviral medication. The most common side effects reported for oseltamivir are nausea and vomiting. Zanamivir can cause bronchospasm (difficulty breathing with wheezing), and peramivir can cause diarrhea. Other less common side effects also have been reported. Your health care provider can give you more information about these drugs or you can check the Food and Drug Administration (FDA) website for specific information about antiviral drugs, including the manufacturer's package insert.

Prevention

Antiviral drugs are not a substitute for getting a flu vaccine. While flu vaccine can vary in effectiveness from season-to-season, a flu vaccine is best way to help prevent seasonal flu and its potentially serious complications. Everyone 6 months and older should receive a flu vaccine every year. Antiviral drugs are a second line of defense that can be used to treat flu (including seasonal flu and novel influenza viruses) if you get sick.

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